Patent Description:
<CIT> discloses a torsion bar with damping properties, preferably for arrangement between a drive unit and a driven shaft, wherein the torsion bar comprises at least a first and a second part, wherein the second part is rotatable relative to the first part against a force provided by a damper. The torsion bar comprises a rod, a central tube and an outer tube, which are mounted on a common axis of rotation and are in operative connection with one another. A torque introduced via the rod in the area of the drive side can be tapped off in the region of the output side on the outer tube.

<CIT> discloses a torsion spring comprising four concentric steel tubes. An inner tube is fixed by one of its ends to a plate, forming a fixed support. Its other end is secured with the corresponding end of a second tube. In turn, the other end of the second tube is secured with the corresponding end of a third tube. The other end of the third tube is secured with the corresponding end of a fourth tube. The other end of the fourth tube forms the second end of the spring, the one on which will exercise the forces causing a twist of the torsion spring.

<CIT> discloses that to transmit torques by means of torsionally elastic shafts, use is made of shafts inserted zigzag-fashion into one another. The proposal is to produce such shafts consisting of a plurality of shaft components connected to one another in this way from composite material, especially fibre-reinforced composite material. All the shaft components and hence the entire shaft are produced in a single operation by winding.

<CIT> discloses a tubular torsion bar including an elongated inner tube of flexible material having a proximal end and a distal end, an elongated outer tube of flexible material having a proximal end and a distal end, a cylindrically shaped joiner bushing fixedly attached to and positioned partially between the distal end of the inner tube and the distal end of the outer tube with the inner tube and outer tube positioned in coaxial and substantially coextensive concentric nesting positions, external apparatus mounting the joiner bushing to maintain axial alignment of the distal and proximal ends of the inner tube and the outer tube and for limited rotational movement, and a mounting and output system fixedly attached to the proximal ends of the inner tube and the outer tube.

<CIT> discloses an apparatus for deploying a wing of a guided missile comprising a fixed wing fixedly coupled to a body of a guided missile, a rotary wing rotatably coupled to the fixed wing, and a deploying portion for rotating the rotary wing into an unfolded state from a folded state by providing a torsion force to the rotary wing.

<CIT> discloses a torsion rod divided into an inner member and at least one tubular outer member which is disposed around and concentrically with such inner member with one end of each of the two or more torsion rods being connected to a respective guide member or a part of a frame of a vehicle while the other ends of the individual torsion rods are connected to each other in the direction of the torsional movement thereof.

In a first aspect, the present disclosure provides a torsion bar spring according to appended claim <NUM>.

In a second aspect, the present disclosure provides a torsion bar spring system according to appended claim <NUM>.

In a third aspect, the present disclosure provides a method for facilitating spring-loaded relative rotation between two components according to appended claim <NUM>.

With regard to torsion springs, conventional spring designs have shortcomings that may preclude their use in certain applications. For example, a torsion bar that achieves a desired angle of rotation may be too long for the space constraints of a given application. Similarly, a coiled torsion spring may have a diameter that exceeds the space constraints of a given application. In such cases, a torsion spring is desired that provides increased energy storage per unit volume and/or per unit mass over conventional torsion spring designs, such that a desired level of spring performance is achieved within a relatively compact space envelope.

Accordingly, a torsion bar spring is disclosed that provides increased energy storage per unit volume and/or per unit mass over conventional torsion spring designs. In one aspect, the torsion bar spring can be used as both an energy storage device and a hinge pin for spring-loaded hinged mechanism applications. The torsion bar spring can include a first elongated spring bar made of a resiliently flexible material. The first elongated spring bar can have a first coupling interface portion at a distal end and an interior opening oriented along a longitudinal axis. The torsion bar spring can also include a second elongated spring bar made of a resiliently flexible material. The second elongated spring bar can have a second coupling interface portion at the distal end. The second elongated spring bar can be disposed at least partially in the interior opening of the first elongated spring bar. The first and second elongated spring bars can be directly coupled to one another at the first and second coupling interface portions such that uncoupled portions of the first and second elongated spring bars are rotatable relative to one another about the longitudinal axis.

In one aspect, a torsion bar spring system is disclosed. The system can include a first component, a second component, and a torsion bar spring operably coupled to the first component and the second component to facilitate relative rotation of the first and second components. The torsion bar spring can include a first elongated spring bar made of a resiliently flexible material. The first elongated spring bar can have a first coupling interface portion at a distal end and an interior opening oriented along a longitudinal axis. The torsion bar spring can also include a second elongated spring bar made of a resiliently flexible material. The second elongated spring bar can have a second coupling interface portion at the distal end. The second elongated spring bar can be disposed at least partially in the interior opening of the first elongated spring bar. The first and second elongated spring bars can be directly coupled to one another at the first and second coupling interface portions such that uncoupled portions of the first and second elongated spring bars are rotatable relative to one another about the longitudinal axis.

Solid and tubular bars subjected to torsional loading are illustrated in <FIG>, respectively, and represent conventional types of torsion bar springs. For a solid circular cross-section bar (<FIG>), the angle of deflection θ is given by: <MAT> and for a tubular circular cross-section bar (<FIG>), the angle of deflection θ is given by: <MAT> where T is torque, L is the length of the bar, J is the polar moment of inertia, G is the shear modulus, do is the outer diameter, and di is the inner diameter.

Torsion bar springs as in <FIG> produce relatively high torque when rotated by a relatively small angular displacement (i.e., angle of twist). From the above equations, it can be seen that bar length and diameter can alter the resulting angular displacement given a required torque. For example, increasing length and decreasing outer diameter can increase angular displacement. Thus, if the same amount of torque is desired over a larger angular displacement, the bar length must increase so as not to over stress the material and cause failure of the spring. However, available design space may not always accommodate such an increase in bar length. The technology of the present disclosure addresses this issue, among other things.

One example of a torsion bar spring <NUM> in accordance with the present disclosure is illustrated in cross-section in <FIG>. In general, the torsion bar spring <NUM> can comprise multiple elongated spring bars <NUM>, <NUM> that can be twisted or torqued about a longitudinal axis <NUM>. The elongated spring bar <NUM> can have an interior opening <NUM> oriented along the longitudinal axis <NUM>. In one aspect, the elongated spring bar <NUM> can have a tubular configuration. The elongated spring bar <NUM> can be disposed at least partially in the interior (through opening <NUM>) of the elongated spring bar <NUM>. The elongated spring bars <NUM>, <NUM> can be axially aligned or concentric about the longitudinal axis <NUM>. The elongated spring bar <NUM> can have any suitable configuration, such as an interior opening <NUM> oriented along the longitudinal axis <NUM> (e.g., a tubular configuration) or the elongated spring bar <NUM> can be solid. A spring bar (e.g., spring bars <NUM>, <NUM>) disclosed herein is considered "elongated" regardless of the diameter and length, since the length will generally be greater than the diameter.

The elongated spring bars <NUM>, <NUM> can also have coupling interface portions <NUM>, <NUM>, respectively, at a distal end 103a of the torsion bar spring <NUM>. The elongated spring bars <NUM>, <NUM> can be directly coupled to one another at the coupling interface portions <NUM>, <NUM> in a manner to transfer torque about the longitudinal axis <NUM>, such that uncoupled portions <NUM>, <NUM> of the elongated spring bars <NUM>, <NUM> are rotatable relative to one another about the longitudinal axis <NUM>. By directly coupling the elongated spring bars <NUM>, <NUM> to one another, torque can be transferred directly between the elongated spring bars, with no intermediate structure or component. As described in further detail below, in some embodiments, the coupling interface portions <NUM>, <NUM> can be configured to facilitate direct coupling to one another with no additional hardware or parts needed. Thus, there is a direct load path from the elongated spring bar <NUM> to the elongated spring bar <NUM>, with no intermediate structure or component in the load path. At a minimum, the elongated spring bars <NUM>, <NUM> can be fixedly coupled to one another at the coupling interface portions <NUM>, <NUM> to prevent relative movement in a rotational degree of freedom about the longitudinal axis <NUM>. It is noted that the elongated spring bars <NUM>, <NUM> can be fixedly coupled to one another at the coupling interface portions <NUM>, <NUM> to prevent relative movement in any suitable rotational and/or translational degree of freedom.

In one aspect, the coupling interface portion <NUM> and/or the coupling interface portion <NUM> can comprise a shoulder or flange extending radially relative to the longitudinal axis <NUM>. For example, as shown in <FIG>, the coupling interface portion <NUM> of the elongated spring bar <NUM> includes a shoulder <NUM> that extends in a radially outward direction relative to the longitudinal axis <NUM>. In some embodiments, the coupling interface portion <NUM> of the elongated spring bar <NUM> can include a shoulder (not shown) that extends in a radially inward direction relative to the longitudinal axis <NUM>. The radial dimension <NUM> of one or more shoulders or flanges (e.g., the shoulder <NUM>) can be equal to a gap <NUM> between the uncoupled portions <NUM>, <NUM> that remain of the elongated spring bars <NUM>, <NUM>. In other words, a shoulder or shoulders can be configured to provide the gap <NUM>. It should be recognized that coupling interface portions can have any suitable configuration.

For example, <FIG> illustrates an end view of elongated spring bar coupling interface portions <NUM>, <NUM>. In this case, outer surfaces <NUM>, <NUM> of the respective coupling interface portions <NUM>, <NUM> have circular cross-sections, which can provide cylindrical or conical surfaces. The coupling interface portions <NUM>, <NUM> can have any suitable type of fit with one another. For example, an inner diameter <NUM> of the outer coupling interface portion <NUM> and an outer diameter <NUM> of the inner coupling interface portion <NUM> can be sized for a clearance fit, a transition fit, or an interference fit. In addition, relative rotation between the coupling interface portions <NUM>, <NUM> about a longitudinal axis <NUM> can be prevented in any suitable manner. For example, an interference fit between the coupling interface portions <NUM>, <NUM> may be sufficient to prevent relative rotation about the longitudinal axis <NUM>. On the other hand, coupling interface portions <NUM>, <NUM> with a clearance or transition fit may be prevented from relative rotation about the longitudinal axis <NUM> by a weld or adhesive at the interface. Thus, in some embodiments, the coupling interface portions <NUM>, <NUM> can be directly coupled to one another with no additional hardware or parts needed. In one aspect, pins or dowels 250a, 250b may be internally fitted at the coupling interface portions <NUM>, <NUM> to provide mechanical resistance to relative rotation about the longitudinal axis <NUM> that is sufficient to prevent such relative rotation. In this case, the coupling interface portions <NUM>, <NUM> can be coupled to one another with no external hardware or parts needed.

<FIG> illustrates an end view of elongated spring bar coupling interface portions <NUM>, <NUM> in accordance with another example. In this case, the coupling interface portions <NUM>, <NUM> comprise complementary protrusions <NUM>, <NUM> that overlap one another in a radial direction <NUM> and are offset from one another in a circumferential arrangement and direction <NUM> about a longitudinal axis <NUM>. The protrusions <NUM>, <NUM> can be of any suitable configuration. For example, the protrusions <NUM>, <NUM> can be splines of any suitable configuration, such as castellated profile splines (as shown) or any other suitable spline profile or shape. The coupling interface portions <NUM>, <NUM> can have any suitable type of fit with one another. For example, the complementary protrusions <NUM>, <NUM> of the coupling interface portions <NUM>, <NUM> can be sized for a clearance fit, a transition fit, or an interference fit. The geometry of the complementary protrusions <NUM>, <NUM> can provide a mechanical resistance to relative rotation between the coupling interface portions <NUM>, <NUM> about the longitudinal axis <NUM> that is sufficient to prevent such relative rotation. In one aspect, the protrusions <NUM>, <NUM> can extend parallel to the longitudinal axis <NUM> or may extend helically about the longitudinal axis <NUM>. In another aspect, the protrusions <NUM>, <NUM> can extend in the radial direction <NUM> from a cylindrical base shape or a conical base shape (i.e., tapering along the longitudinal axis <NUM>). In a further aspect, radial heights 344a, 344b of the respective protrusions <NUM>, <NUM> can be constant or variable (e.g., tapering in height) along the longitudinal axis <NUM>. In addition, a weld or adhesive can be applied at the interface of the protrusions <NUM>, <NUM> to fix the coupling interface portions <NUM>, <NUM> to one another. Thus, the coupling interface portions <NUM>, <NUM> can be directly coupled to one another with no additional hardware or parts needed.

Referring again to <FIG>, with the elongated spring bars <NUM>, <NUM> coupled to one another in series, the torque carried by each elongated spring bar is identical. Therefore, the elongated spring bar <NUM> and the elongated spring bar <NUM> can be designed to handle the same torque. If one elongated spring bar is significantly stronger than another, then the torsion bar spring <NUM> will not be optimized. The stronger elongated spring bar will have unnecessary mass and stiffness, both of which reduce the performance. Therefore, geometry of the respective elongated spring bars <NUM>, <NUM>, such as wall thicknesses 145a, 145b and/or inner diameters 146a, 146b, are interrelated and can vary in a corresponding manner due to the elongated spring bars <NUM>, <NUM> being subjected to the same torque. As mentioned above, the inner elongated spring bar <NUM> can be solid or tubular. Thus, the inner diameter 146b of the elongated spring bar <NUM> can vary between zero (i.e., a solid bar) and a maximum amount that may be limited by factors such as the inner diameter 146a of the elongated spring bar <NUM>, the wall thickness 145b of the elongated spring bar <NUM>, and the gap <NUM> between the uncoupled portions <NUM>, <NUM> of the elongated spring bars <NUM>, <NUM>.

In many cases, space constraints will dictate maximum outer dimensions of the torsion bar spring <NUM> in addition to torque and/or displacement requirements. Thus, given a desired gap <NUM>, the wall thicknesses 145a, 145b of the respective elongated spring bars <NUM>, <NUM> are variable to achieve a desired or optimized design. As the wall thickness 145a of the outer elongated spring bar <NUM> increases to accommodate a given torque, the wall thickness 145b of the inner elongated spring bar <NUM> can also increase until the wall thickness equals the radius of the elongated spring bar <NUM> at which point the inner elongated spring bar <NUM> is solid. On the other hand, some torsion bar spring designs may not need to accommodate a physical space, but may instead be driven primarily by a required maximum torque. In this case, an inner elongated spring bar may drive the dimensions. For example, the inner elongated spring bar <NUM> may be solid and the thickness 145a of the outer elongated spring bar <NUM> may be adjusted accordingly while preserving a given desired gap <NUM> between the uncoupled portions <NUM>, <NUM> of the elongated spring bars <NUM>, <NUM>. As the wall thickness 145b of the inner elongated spring bar <NUM> increases, the wall thickness 145a of the outer elongated spring bar <NUM> can increase (if space permits) to preserve the gap <NUM> and/or a higher strength material may be selected for use in one or both of the elongated spring bars <NUM>, <NUM> in order to maintain a thinner wall thickness. Thus, performance of the torsion bar spring <NUM> can be optimized by varying dimensions of the elongated spring bars <NUM>, <NUM> while ensuring stress margins are maintained.

One advantage of the torsion bar spring <NUM> is that with the elongated spring bar <NUM> nested within the elongated spring bar <NUM>, the torsion bar spring <NUM> can simulate additional length and decreasing diameter without actually changing the overall size envelope (e.g., increasing overall length). The result is an increase in angular displacement at a given maximum torque and an increase in potential energy storage in a compact volume (i.e., an increase in energy density per unit volume).

The elongated spring bars <NUM>, <NUM> can be made of any suitable resiliently flexible material, such as metal (e.g., alloys based on iron, titanium, aluminum, nickel, etc.), fiber-reinforced composite (e.g., carbon fiber, glass fiber, aramid fiber, etc.), and/or various high modulus reinforced engineering plastics (e.g., fiber reinforced PEEK, glass filled PET, or various filled aromatic polyimides). In one aspect, the elongated spring bars <NUM>, <NUM> can be made of different resiliently flexible materials. In another aspect, the elongated spring bars <NUM>, <NUM> can be made of the same resiliently flexible material. In a particular example, the elongated spring bars <NUM>, <NUM> can be made of a metal material, such as steel or titanium. In this case, the coupling interface portions <NUM>, <NUM> can be welded to one another by any suitable technique or process (e.g., electron beam welding, orbital welding, etc.). Thus, precision elongated spring bars <NUM>, <NUM> can be made from identical material, welded together at the coupling interface portions <NUM>, <NUM>, and heat-treated to produce a highly reliable torsion bar spring. In another example, an adhesive, such as an epoxy, can be used to secure the coupling interface portions <NUM>, <NUM> to one another, although other materials or methods may be used.

The torsion bar spring <NUM> can also include mounting portions <NUM>, <NUM> associated with each of the elongated spring bars <NUM>, <NUM>, respectively, to facilitate coupling the torsion bar spring <NUM> to external components, such as an input device and/or a driven component. In the example illustrated in <FIG>, the mounting portions <NUM>, <NUM> are associated with the respective elongated spring bars <NUM>, <NUM> at a proximal end 103b of the torsion bar spring <NUM>. The mounting portions <NUM>, <NUM> can have any configuration that can be used to attach the torsion bar spring <NUM> to external components or devices. For example, the mounting portions <NUM>, <NUM> can have external features 117a, 127a, such as parallel flat surfaces or splines, configured to mate or interface with external components. In another example, the mounting portions <NUM>, <NUM> can have internal features 117b, 127b, such as threaded holes or sockets, configured to mate or interface with external components. In general, the mounting portions <NUM>, <NUM> are located at ends of the uncoupled portions <NUM>, <NUM> of the elongated spring bars <NUM>, <NUM> opposite the coupling interface portions <NUM>, <NUM> and are exposed to facilitate coupling with external components. Due to the even number of elongated spring bars, the mounting portions <NUM>, <NUM> are located at the same end of the torsion bar spring <NUM>.

Although the interior opening <NUM> of the elongated spring bar <NUM> is shown as a blind opening due to the illustrated configuration of the internal mounting feature 127b, it should be recognized that the interior opening <NUM> may extend completely through the elongated spring bar <NUM> along the longitudinal axis <NUM>.

In one aspect, an outer surface <NUM> of the outer elongated spring bar <NUM> can be configured as a locating feature and/or a bearing surface for interfacing with an external component to maintain a positional relationship of the external component about the axis <NUM>. In this case, the torsion bar spring <NUM> can also serve as a hinge pin for external components that rotate about the axis <NUM>. The torsion bar spring <NUM> can therefore provide the dual functions of maintaining a pivot or hinge connection between two components and providing energy storage/return for the components (e.g., a spring-loaded hinged mechanism).

<FIG> illustrates a torsion bar spring <NUM> in accordance with another example of the present disclosure. The torsion bar spring <NUM> is similar to the torsion bar spring <NUM> in many respects. For example, the torsion bar spring <NUM> includes multiple elongated spring bars <NUM>, <NUM>, <NUM> made of resiliently flexible materials that can be twisted or torqued about a longitudinal axis <NUM>. The elongated spring bars <NUM>, <NUM> can have interior openings <NUM>, <NUM> oriented along the longitudinal axis <NUM>. In one aspect, the elongated spring bars <NUM>, <NUM> can each have a tubular configuration. The elongated spring bar <NUM> can be disposed at least partially in the interior opening <NUM> of the elongated spring bar <NUM>. The elongated spring bars <NUM>, <NUM> have coupling interface portions <NUM>, 422a, respectively, at a distal end 403a of the torsion bar spring <NUM>. The elongated spring bars <NUM>, <NUM> can be directly coupled to one another at the coupling interface portions <NUM>, 422a in a manner to transfer torque about the longitudinal axis <NUM>, such that uncoupled portions <NUM>, <NUM> of the elongated spring bars <NUM>, <NUM> are rotatable relative to one another about the longitudinal axis <NUM>.

In this case, the elongated spring bar <NUM> also includes a coupling interface portion 422b at a proximal end 403a of the torsion bar spring <NUM>. The elongated spring bar <NUM> can be disposed at least partially in the interior opening <NUM> of the elongated spring bar <NUM>. The elongated spring bar <NUM> also includes a coupling interface portion <NUM> at the proximal end 403a of the torsion bar spring <NUM>. Thus, the elongated spring bars <NUM>, <NUM> can be directly coupled to one another at the coupling interface portions 422b, <NUM> in a manner to transfer torque about the longitudinal axis <NUM>, such that uncoupled portions <NUM>, <NUM> of the elongated spring bars <NUM>, <NUM> are rotatable relative to one another about the longitudinal axis <NUM>. The elongated spring bars <NUM>, <NUM>, <NUM> can be axially aligned or concentric about the longitudinal axis <NUM>. The elongated spring bar <NUM> can have any suitable configuration, such as an interior opening (not shown) oriented along the longitudinal axis <NUM> (e.g., a tubular configuration) or the elongated spring bar <NUM> can be solid, as shown.

The coupling interface portions <NUM>, 422a, 422b, <NUM> can have any suitable configuration. In one aspect, one coupling interface portion can include a shoulder or flange extending radially relative to the longitudinal axis <NUM> and a corresponding coupling interface portion can include a recess configured to mate with and receive a portion of the shoulder or flange. In the example illustrated in <FIG>, the coupling interface portion <NUM> of the elongated spring bar <NUM> includes a shoulder <NUM> that extends in a radially inward direction relative to the longitudinal axis <NUM>. In addition, the coupling interface portion 422a of the elongated spring bar <NUM> includes a recess 424a configured to mate with and receive a portion of the shoulder <NUM>. The shoulder <NUM> and the recess 424a can be configured to provide a gap 441a between the uncoupled portions <NUM>, <NUM> of the elongated spring bars <NUM>, <NUM>. It should be recognized that although the coupling interface portion <NUM> in this example includes the shoulder <NUM> and the coupling interface portion 422a includes the recess 424a, in some embodiments, the coupling interface portion <NUM> can include a recess and coupling interface portion 422a can include a shoulder.

In another aspect, corresponding coupling interface portions can each comprise a shoulder or flange extending radially relative to the longitudinal axis <NUM>. For example, the coupling interface portion 422b of the elongated spring bar <NUM> includes a shoulder 424b that extends in a radially inward direction relative to the longitudinal axis <NUM>, and the coupling interface portion <NUM> of the elongated spring bar <NUM> includes a shoulder <NUM> that extends in a radially outward direction relative to the longitudinal axis <NUM>. The shoulders 424b, <NUM> can be configured to provide a gap 441b between the uncoupled portions <NUM>, <NUM> of the elongated spring bars <NUM>, <NUM>.

Geometry of the elongated spring bars <NUM>, <NUM>, <NUM>, such as diameter (e.g., inner diameters 446a-b and outer diameter 446c), wall thickness (e.g., wall thicknesses 445a-b), etc., can be determined as described above, in this case, accounting for a third elongated spring bar <NUM>. Coupling a series of nested elongated spring bars at opposite ends can provide a compact assembly configured to meet the requirements of a given design. It should be recognized that any number of elongated spring bars can be utilized having any suitable dimension to achieve a given angular displacement at a given maximum torque and/or to maintain an adequate stress margin.

The torsion bar spring <NUM> can also include mounting portions <NUM>, <NUM> associated with each of the elongated spring bars <NUM>, <NUM>, respectively, to facilitate coupling the torsion bar spring <NUM> to external components, such as an input device and/or a driven component. In the example illustrated in <FIG>, the mounting portion <NUM> is associated with the elongated spring bar <NUM> at the proximal end 403b of the torsion bar spring <NUM>, and the mounting portion <NUM> is associated with the elongated spring bar <NUM> at the distal end 403a of the torsion bar spring <NUM>. Due to the odd number of elongated spring bars, the mounting portions <NUM>, <NUM> are located at opposite ends of the torsion bar spring <NUM>.

<FIG> illustrates a perspective view of a torsion bar spring <NUM> in accordance with an example of the present disclosure. The torsion bar spring <NUM> may have a similar configuration to the torsion bar spring <NUM> of <FIG>, where elongated spring bars are arranged such that mounting portions <NUM>, <NUM> for coupling the torsion bar spring <NUM> to external components are located at opposite ends (e.g., distal 503a and proximal 503b ends) of the torsion bar spring <NUM>. In one aspect, the torsion bar spring <NUM> can be configured as a hinge pin for use in a mechanism that requires torsional forces or torque between two connected external components (e.g., a spring-loaded hinged mechanism). In this case, an outer surface <NUM> of an outer elongated spring bar <NUM> can be configured as a locating feature and/or a bearing surface for interfacing with external components to maintain a positional relationship of the external components about the axis <NUM>. The torsion bar spring <NUM> can therefore be a multifunctional device that can act not only as a spring, but as a hinge pin as well, thus eliminating the need for an external torsion spiral spring that may otherwise be associated with a hinge pin in such applications. Due to the compact nature of the torsion bar spring <NUM> and its multifunctional aspect of a self-contained spring-loaded hinge pin, the torsion bar spring <NUM> can minimize part count, volume, and weight in many applications.

<FIG> illustrates a cross-sectional side view of an end of an elongated spring bar in accordance with another example. In this case, coupling interface portions <NUM>, <NUM> of respective elongated spring bars <NUM>, <NUM> are configured to facilitate welding to one another. For example, the coupling interface portion <NUM> includes one or more openings <NUM> that can be configured to receive weld or adhesive material and provide access to a surface of the <NUM> of the coupling interface portion <NUM>. In some embodiments, a plug weld can be applied to the openings <NUM> and the surface <NUM> to couple the coupling interface portions <NUM>, <NUM> to one another. This approach can be beneficial when utilizing relatively thin-walled elongated spring bars, such as the elongated spring bars <NUM>, <NUM>. The elongated spring bar <NUM> can be tapered or swaged <NUM> between an uncoupled portion of the elongated spring bar <NUM> and the coupling interface portion <NUM>. In one aspect, a mounting portion <NUM> associated with an elongated spring bar <NUM> can have internal features <NUM> (i.e., openings or holes) configured to receive one or more protrusions of an external component.

<FIG> illustrates an end view of a mounting portion <NUM> of an elongated spring bar, in accordance with another example. In this case, the mounting portion <NUM> has external features <NUM>, such as protrusions, configured to mate or interface with an external component. This configuration can be beneficial when utilizing relatively thin-walled elongated spring bars.

<FIG> illustrates a torsion bar spring system <NUM> in accordance with an example of the present disclosure. The system <NUM> can include components <NUM>, <NUM> and a torsion bar spring <NUM> operably coupled to the components <NUM>, <NUM> to facilitate relative rotation of the components <NUM>, <NUM>. The torsion bar spring <NUM> can be of any suitable configuration disclosed herein. In the illustrated example, the torsion bar spring <NUM> is configured similar to the torsion bar springs <NUM> and <NUM>, where elongated spring bars are arranged such that mounting portions <NUM>, <NUM> for coupling the torsion bar spring <NUM> to the external components <NUM>, <NUM> are located at opposite ends (e.g., distal 803a and proximal 803b ends) of the torsion bar spring <NUM>. The system <NUM> can be considered a type of spring-loaded hinged mechanism that requires torsional force or torque between the connected components <NUM>, <NUM>. In one aspect, an outer surface <NUM> of an outer elongated spring bar <NUM> can be configured as a locating feature and/or a bearing surface for interfacing with the components <NUM>, <NUM> to maintain a positional relationship of the components <NUM>, <NUM> about an axis <NUM>. In this case, the torsion bar spring <NUM> can be configured as a hinge pin for the spring-loaded hinged mechanism of the system <NUM>.

In the illustrated example, the component <NUM> can be the body of a missile and the component <NUM> can be a control surface of the missile. It should be apparent that torsion bar springs as disclosed herein can be used in many military and commercial applications, such as in deployable/retractable devices (e.g., fins, wings, launcher lugs, seeker/sensor optics covers, etc.) or to offset motor torque needed when moving objects (e.g., hinged covers/lids, doors, etc.). In one example, a torsion bar spring as disclosed herein can be used in the regenerative braking of a vehicle where the stored energy is released to assist acceleration.

In accordance with one example, a method for facilitating spring-loaded relative rotation between two components is disclosed. The method can comprise obtaining a first elongated spring bar made of a resiliently flexible material and having a first coupling interface portion at a distal end and an interior opening oriented along a longitudinal axis. The method can also comprise obtaining a second elongated spring bar made of a resiliently flexible material and having a second coupling interface portion at the distal end. The method can further comprise disposing the second elongated spring bar at least partially in the interior opening of the first elongated spring bar, wherein the first and second elongated spring bars are directly coupled to one another at the first and second coupling interface portions such that uncoupled portions of the first and second elongated spring bars are rotatable relative to one another about the longitudinal axis. Additionally, the method can comprise facilitating coupling a first component to the first elongated spring bar and coupling a second component to the second elongated spring bar. It is noted that no specific order is required in this method, though generally in one embodiment, these method steps can be carried out sequentially.

In the description, numerous specific details are provided, such as examples of lengths, widths, shapes, etc., to provide a thorough understanding of embodiments of the invention.

Claim 1:
A torsion bar spring (<NUM>, <NUM>), comprising:
a first elongated spring bar (<NUM>, <NUM>, <NUM>) made of a resiliently flexible material and having a first coupling interface portion (<NUM>, <NUM>, <NUM>, <NUM>) at a distal end and an interior opening (<NUM>, <NUM>) oriented along a longitudinal axis (<NUM>, <NUM>); and
a second elongated spring bar (<NUM>, <NUM>, <NUM>) made of a resiliently flexible material and having a second coupling interface portion (<NUM>, 422a, <NUM>) at the distal end,
wherein the second elongated spring bar is disposed at least partially in the interior opening of the first elongated spring bar and the first and second elongated spring bars are directly fixedly coupled to one another at the first and second coupling interface portions such that uncoupled portions of the first and second elongated spring bars are rotatable relative to one another about the longitudinal axis; and
characterised in that the first coupling interface portion includes one or more openings (<NUM>) configured to receive weld material and to provide access to a surface (<NUM>) of the second coupling interface portion for application of a plug weld to the one or more openings and the surface, to couple the first coupling interface portion and the second coupling interface portion to one another.