EP4676568A1

EP4676568A1 - Torsion spring for medicament delivery device

Info

Publication number: EP4676568A1
Application number: EP24706452.0A
Authority: EP
Inventors: Hsin-Ping Liu; Tsung-Yen Lu
Original assignee: SHL Medical AG
Current assignee: SHL Medical AG
Priority date: 2023-03-07
Filing date: 2024-02-23
Publication date: 2026-01-14
Also published as: WO2024184093A1

Abstract

A torsion spring for use in a medicament delivery device, wherein the torsion spring is formed from a wire with a diameter d, wherein the torsion spring is configured to rotate around a rotational axis of a mandrel of the medicament delivery device and to store a predetermined amount of energy, when wound a predetermined number of windings, W, around the rotational axis; wherein the torsion spring comprises: at least a distal end portion, a central portion, and proximal end portion; and wherein the distal end portion, the central portion, and the proximal end portion are formed essentially next to each other with respect the mandrel of the medicament delivery device.

Description

TITLE

Torsion Spring for Medicament Delivery Device

TECHNICAL FIELD

The present invention relates to a torsion spring for a medicament delivery device.

BACKGROUND

Medicament delivery devices may be designed to automatically perform a medicament administration operation, i.e. , to expel a drug or medicament. Such an operation may be triggered by the user when interacting with the medicament delivery device.

The user may for example initiate a medicament administration operation by moving a needle cover extending from the housing into the housing or by pushing a button provided on the medicament delivery device. This movement may trigger internal components to cause an automatic medicament expulsion. One example of medicament delivery devices of this type is auto-injectors.

WO 2021/104885 A1 discloses a medicament delivery device comprising a resilient blocking member, a plunger rod, a driver, and a power pack assembly. The driver is configured to be connected to the power pack assembly. Furthermore, the driver is configured to be rotated by the power pack assembly. The power pack assembly comprises a rotation device. The rotation device may be an exemplary torsion spring.

Fig. 1A shows an exemplary torsion spring of the prior art and portions of a medicament delivery device. As discussed above, a medicament delivery device may comprise a syringe 1 . A medicament in the syringe 1 may be expulsed, when a plunger rod 2 moves in a proximal direction within the syringe 1 . The plunger rod 2 may be moved by a driver 21 and the driver 21 may be rotated by a power pack assembly. The power pack assembly may comprise a proximal rotational portion 22, a rotational device, and a distal rotational portion 23. The rotational device may be a torsion spring 3. The exemplary torsion spring 3 comprises a proximal hook 31 and a distal hook 32. Each of the hooks 31 and 32 is configured to engage with a respective seat or socket 21 a or 23a formed at the proximal rotational portion 22 and the distal rotational portion 22, respectively, in order to transfer kinetic energy stored in the torsion spring 3 to the power pack assembly. That is, to rotate to power pack assembly in order to drive the driver 21 .

SUMMARY

In order to deliver large volumes of a viscous drug, preferably of a high viscous drug, with auto-injectors and/or within in a short amount of time, a powerful spring is needed. Compression springs are most common in the state of the art but do not provide enough power.

Thus, a more powerful spring is needed, and a corresponding compression spring may not fit inside the auto-injector. For such cases a torsion spring, which is powerful and affordable, is preferred. Therefore, a torsion spring is used in the example above (WO 2021/104885 A1) and in many other auto-injectors.

One major challenge is that, when a torsion spring is loaded with a lot of power, it undergoes a lot of geometrical change, that is, it may start short and wide and when it is loaded it may become long and narrow. This large deformation increases the probability of coil overlap.

Furthermore, current torsion spring designs usually use a 180-degree bent hook design to hold the spring in place, i.e., in a seat on a rotational part of the power pack assembly, at both ends of the torsion spring. Because of the bending process this type of design is complex and is costly to produce.

Furthermore, a spring of said design is difficult to assemble, because during assembly each of the hooks needs to be placed and secured into a corresponding mating component, i.e., aforementioned seat. On the one hand, the hook needs to be tightly constrained after successful assembly, while on the other hand, it is difficult to precisely move the spring in a tight space.

This problem even amplified, because the spring wire typically is cut sharply, and the hook may thus easily jam when the hook is assembled into a hook slot on the mating component.

When a torsion spring is loaded, it is done so by rotating the spring. When the spring is rotated to load it, the number of coils of the spring increases, that is, the “solid length” increases. This means that if a spring would be made without gaps between the coils it would get longer and would not fit in the assembly space.

In order to allow for the length, increase during loading, axial space between the coils is needed, when the spring is assembled, i.e. , before it is rotated to be loaded. There are many options for “where” to add that axial space. It can be equally distributed between all coils, which is referred to as uniform coil spacing, i.e., a little free space is added between each coil.

Alternatively, there can be space between only some of the coils, which are then referred to as open coils, while keeping other coils without space, which are referred to as closed coils

Current torsion spring designs use either uniform coil spacing, or open coils on only one side of the spring. These springs have problems with spring stability and coils overlapping each other, which is due to coils being close to the axially supporting surfaces on the mating components.

Current torsion spring designs typically feature an equal outer diameter throughout the length of the spring. Since the spring guide rod, also referred to as mandrel, is much narrower, this results to the spring showing an eccentric behavior, moving around like a “hula hoop”. This behavior further increases the risk of overlapping.

It is noted that the term mandrel may also, depending on the example of a medicament delivery device, refer to any other member of the medicament delivery device, which is at least partially located within the torsion spring and configured enable winding and/or unwinding of the torsion spring.

It is noted that whenever this disclosure refers to measures of the spring, in particular to a diameter, to a distance between wires, or a pitch, these measures are defined, unless mentioned otherwise, for the unloaded spring. The skilled person is aware that during loading the spring may undergo a deformation.

An object of the present disclosure is to provide a medicament delivery device which solves, or at least mitigates, problems of the prior art. The above problems are among those solved by the present disclosure as defined in the appended claims.

The torsion spring of the present disclosure is formed from a wire with a diameter d, which is essentially uniform over the entire length. The wire preferably is a metal wire, preferred materials are one of: stainless steel, more preferably T302, AISI 301 , SUS304, or an alloy with high non-magnetic proportion, more preferably 90% nonmagnetic.

The torsion spring of the present disclose is configured to rotate around a rotational axis of a mandrel of the medicament delivery device as described above.

The torsion spring of the present disclose is further configured to store a predetermined amount of energy when wound a predetermined number of windings, W, around said rotational axis.

An embodiment of the present disclosure relates to a torsion spring for use in a medicament delivery device, wherein the torsion spring is formed from a wire with a diameter d, wherein the torsion spring is configured to rotate around a rotational axis of a mandrel of the medicament delivery device and to store a predetermined amount of energy, when wound a predetermined number of windings, W, around the rotational axis; wherein the torsion spring comprises: at least a distal end portion, a central portion, and proximal end portion . The distal end portion, the central portion, and the proximal end portion are formed essentially next to each other with respect the mandrel of the medicament delivery device. In one example, the torsion spring consists of the distal end portion, the central portion, and the proximal end portion.

In one example, the torsion spring further comprises free ends formed as a straight leg essentially protruding only in a plane defined by a respective last coil of the torsion spring.

In one example, coils of the central portion have a first uniform pitch; coils of the distal end portion and the proximal end portion each have a pitch higher than the first uniform pitch.

In one example, the distal end portion has a second uniform pitch; the proximal end portion has a third uniform pitch; and the second uniform pitch and the third uniform pitch are preferably a same pitch.

In one example, the coils of the central portion have essentially zero pitch.

In one example, a length L is the sum of a total length, measured along the rotational axis, of the distal end portion and the proximal end portion and is calculated the diameter of the wire d times the predetermined number of windings W.

In one example, length L is essentially evenly distributed to the proximal end portion and the distal end portion.

In one example, the torsion spring is further comprising at least one dead coil with essentially zero pitch at the distal end of the torsion spring and at the proximal end of the torsion spring, respectively; and preferably comprising two dead coils at each end of the torsion spring.

In one example, the at least one dead coil has diameter, d2, defining a final diameter of all coils of the torsion spring after the torsion spring is wound up with the predetermined number of windings W.

In one example, the coils of the central portion have a first uniform diameter, d1 , and wherein the ratio of the diameter of the at least one dead coil, d2, and the first uniform diameter is calculated by: d.2 N di ⁼ N + W with N being a number of active coils, when the torsion spring is not wound.

In one example, the coils of the distal end portion and the proximal end portion each have diameter smaller than the first uniform diameter.

In one example, the straight legs are protruding in a tangential direction of the respective last coil; or the straight legs are protruding in a radial direction of the respective last coil.

In embodiment of the present disclosure relates to a medicament delivery device with a torsion spring according to any one of the preceding embodiments and examples, wherein the medicament delivery device comprises a power pack assembly with at least a proximal rotational part and a distal rotational part, each rotational part with a respective seat for holding the torsion spring; wherein torsion spring has tangential straight legs; and wherein the seats are essentially c-shaped protrusions opening in a tangential direction of the rotational parts in a direction against the rotation of the spring during winding.

In one example, the diameter d2 of the dead coil is essentially the diameter of a mandrel of the medicament delivery device.

It is a first general inventive concept of the present disclosure, to use a straight leg design for the free ends of the torsion spring. That is, the free ends protrude essentially straight in the plane defined by the last coil of the spring.

In a preferred embodiment, the straight legs are tangentially, with respect to the last coil, protruding from the last coil, however, radially, with respect to that last coil, protruding legs are also possible.

Tangentially protruding legs are preferred because they do not require any extra bending process of the wire during production. This type of leg is also much easier to assemble because it may be place anywhere between the mating components and may then be rotated until the legs fall into their indented positions.

It is a second general inventive concept of the present disclosure, to use a sparse- dense-sparse design with regard to the pitch of the coils of the torsion spring. That is to use open coils at both end portions of the torsion spring and closed coils in a center portion of the spring.

In this design the closed coils at the center of the spring, show superior resistance against overlapping during testing, when comparing to both a uniform distribution and/or a sparse-dense design of the prior art.

It is a third general inventive concept of the present disclosure, to introduce narrow coils at both ends of the spring. That is, coils with a reduced diameter compared to the coils of the center portion.

This helps centering the spring and preventing a hula-hoop behavior and thus reduces the probability of coils overlapping.

In the present disclosure, when the term “distal direction” is used, this refers to the direction pointing away from the dose delivery site during use of the medicament delivery device. When the term “distal part/end” is used, this refers to the part/end of the delivery device, or the parts/ends of the members thereof, which during use of the medicament delivery device is/are located furthest away from the dose delivery site. Correspondingly, when the term “proximal direction” is used, this refers to the direction pointing towards the dose delivery site during use of the medicament delivery device. When the term “proximal part/end” is used, this refers to the part/end of the delivery device, or the parts/ends of the members thereof, which during use of the medicament delivery device is/are located closest to the dose delivery site.

Further, the terms “longitudinal”, “longitudinally”, “axially” and “axial” refer to a direction extending from the proximal end to the distal end and along the device or components thereof, typically in the direction of the longest extension of the device and/or component. Similarly, the terms “transverse”, “transversal” and “transversally” refer to a direction generally perpendicular to the longitudinal direction.

Further, the terms “circumference”, “circumferential”, or “circumferentially” refer to a circumference or a circumferential direction relative to an axis, typically a central axis extending in the direction of the longest extension of the device and/or component. Similarly, “radial” or “radially” refer to a direction extending radially relative to the axis, and “rotation”, “rotational” and “rotationally” refer to rotation relative to the axis.

Generally, all terms used in the claims are to be interpreted according to their ordinary meaning in the technical field, unless explicitly defined otherwise herein. All references to a/an/the element, apparatus, member, component, means, etc. are to be interpreted openly as referring to at least one instance of the element, apparatus, member component, means, etc., unless explicitly stated otherwise.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the present disclosure will now be described by way of example only and with reference to the following accompanying drawings, in which

Fig. 1 A shows an exploded perspective partial view of an exemplary medicament delivery device of the prior art. The two enlargements show the proximal and distal seat area of a torsion spring according to an example.

Fig. 1 B illustrates the deformation of a torsion spring during loading of the spring.

Fig. 2 shows a torsion spring according to a first embodiment of the present disclosure.

Fig. 3 shows a torsion spring according to a second embodiment of the present disclosure.

Fig. 4A illustrates tangential legs according to an embodiment of the present disclosure.

Fig. 4B illustrates radial legs according to an embodiment of the present disclosure. DETAILED DESCRIPTION

The inventive concept will now be described more fully hereinafter with reference to the accompanying drawings, in which exemplifying embodiments are shown. The inventive concept may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided by way of example so that this disclosure will be thorough and complete, and will fully convey the scope of the inventive concept to those skilled in the art. Like numbers refer to like members throughout the description.

Fig. 1 B illustrates the deformation of a torsion spring during loading of the spring. As discussed above, the main problem when using a torsion spring is the risk of overlapping coils during loading the spring. The overlapping coils may cause a spring jam during loading.

There are multiple factors for the risk of overlapping coils. One of the factors is the eccentric movement of the coils. The eccentric movement is caused by the last coils being fixed at a point off-center with regard to the rotational axis, i.e. , the mandrel. Because of the eccentric movement of the coils, the end portions of the spring may tilt away from the original coil plane of the unloaded spring.

Another factor is the deformation of the coil during the loading process. That is, a middle portion of the spring deforms in a direction transverse to the direction to which the spring extends, as shown in Fig. 1 B and indicated by the arrows pointing towards the spring.

In detail, this deformation is illustrated in Fig. 1 B. In the upper portion a less loaded spring is shown, in the lower portion a more loaded spring is shown. The deformation might also cause the end portions of the spring more easily tilting away from the original coil plane of the unloaded spring.

As illustrated, both end portions 33 and 34 of the spring tend to tilt away from the original coil plane of the unloaded spring. That results in two tilt angles 01 and 02 and the first portion of the spring 33 and a second portion of the spring 34 being tilted toward each other. At some point in the center portion of the spring, a coil squeeze is generated.

During the loading the tilt angles increase and at the same time the coil diameter D decreases, which results in a more severe coil squeeze and eventually in a coil overlap.

In summary, during windup, the torsion spring tends to tilt and to squeeze into a parallelogram shape. Furthermore, the mating mechanism needs to be loose in order to allow for a reasonable assembly, however, if they are too loose, they may cause a first coil tilt. Still further, the eccentric arrangement of the hook may also cause the parallelogram shape.

Possible solutions may be an outer guider, essentially guiding the spring and preventing the tilt; an additional extension of the spring during wind-up, which increases the pitch temporally; or a holder for the first coils, which prevents the tilt.

However, all of said solutions require additional parts and/or additional procedural effort for loading the spring during assembly of the medicament delivery device.

Fig. 2 shows a torsion spring 4 according to a first embodiment of the present disclosure. The spring 4 comprises a first portion 42, hereinafter also referred to as proximal end portion. The spring 4 further comprises a second portion 43, hereinafter also referred to as central portion 43. Still further the spring comprises a third portion 44, hereinafter also referred to as distal end portion.

It is noted that the spring design is essentially axially and radially symmetric. Any designation of a direction may refer to the spring in use in a medicament delivery device.

In a preferred example, the coils of the first-, second- and third portion have a different coil density. While the proximal end portion 42 and distal end portion 44 are sparsely wound, the central portion 43 is densely wound. In terms of a pitch, i.e., the distance between the center of adjacent wires of the coils, the proximal end portion 42 and the distal end portion 44 have a higher pitch compared to the central portion 43.

The effect of the sparse-dense-sparse design is that the sparse portions are stiffer, and the dense portion is softer, relative to each other.

Such design may prevent the ends of the spring from tiling. That is, the sparse portions may tend to rotate during wind-up and the dense portion tends to shift more during wind-up. Said rotating and shifting are essentially countereffects, which may balance each-other to prevent coil overlap during wind-up.

Furthermore, the sparse portions are preferably configured to provide a space for the dense portion, so that the dense portion will not jam, when the density between the coils further increases, during the wind-up of the spring.

The total length L of the sparse portions measured along the rotational axis of the spring is equal to the diameter d of the wire times the number of windings W that the spring is configured to be wound:

L = d * W

In a preferred example, the coil density is symmetrically distributed, i.e., the proximal end portion 42 and the distal end portion 44 have essentially the same pitch. Preferably, the total length L of the sparse portions is evenly distributed to the proximal end portion 42 and the distal end portion 44. That is, the length of the proximal end portion 42 and of the distal end portion 44 is essentially the same and preferably L/2.

Additionally, in another preferred example, the pitch in the central portion 43 is essentially zero, i.e., a closed coil design, all coils are adjacent to one another.

It should be noted that as mentioned above, increasing the pitch of the spring in general can add extra extension to the spring and help to prevent tilt issue. As discussed above, the pitch of the central portion 43 is essentially constant, i.e., a first uniform pitch, preferably zero, i.e., closed coils.

The pitch of the proximal end portion 42 is preferably higher than the first uniform pitch.

The pitch of the distal end portion 44 is preferably higher than the first uniform pitch.

In one example, the pitch of the proximal end portion 42 may be essentially homogenous over the entire proximal end portion 42, i.e., the proximal end portion has a second uniform pitch.

In one example, the pitch of the proximal end portion 42 may be increasing along the at least a portion of the length of the entire proximal end portion 42.

In one example, the pitch of the proximal end portion 42 may be constantly increasing along the at least a portion of the length of the entire proximal end portion 42.

In one example, the pitch of the distal end portion 44 may be essentially homogenous over the entire proximal end portion 44, i.e., the distal end portion 44 has a third uniform pitch.

In one example, the pitch of the distal end portion 44 may be increasing along the at least a portion of the length of the entire the distal end portion 44.

In one example, the pitch of the distal end portion 44 may be constantly increasing along the at least a portion of the length of the entire the distal end portion 44.

In a preferred example the pitch distribution of the proximal end portion 42 and the of the distal end portion 44 is symmetric along the rotational axis with respect to the central portion 43.

In a preferred example the second uniform pitch and the third uniform pitch are the same. In one example, between the proximal end portion 42 and the central end portion 43 the torsion spring 4 comprises a first plurality of transition coils (not shown) and between the central portion 43 and the distal end portion 44 the spring comprises a second plurality of transition coils (not shown). The transition coils are configured to match the pitch difference between the portions of the torsion spring.

Additionally or alternatively, in one example, the coils of the first-, second- and third portion have a different coil diameter.

In one example the proximal end portion 42 and the distal end portion 44 have at least some coils with a smaller diameter, the coils of the central portion 43 have a larger diameter, relative to each other.

The effect of the reduced diameter in the respective end portions is that the diameter is closer to the diameter of the mandrel and thus the eccentricity is reduced, which prevents the hula-hoop behavior, as discussed above, thus the coil overlap is reduced.

Additionally or alternatively, in a preferred example, each the distal end and the proximal end of the torsion spring comprises at least one dead coil, i.e., a generally immovable coil, respectively, extending to a free end.

Adding dead coil at the two ends of the spring strengths the structure of the spring, thus, the spring is more suitable to be fed in the assembling line with a bowl feeder.

Preferably the torsion spring comprises two dead coils at each end. This is shown in Fig. 3. The spring comprises two dead coils 42a, at the free end of each of the proximal end portion 42 and the distal end portion 44. In this example, the dead coils 42a essentially have the same reduced diameter as the mandrel and also have zero pitch.

Furthermore, the dead coil design may prevent the spring from moving eccentrically, and thus prevent the tilt of the coils.

In one example, where the torsion spring comprises dead coils at the distal end and the proximal end, respectively, the above-mentioned sparse proximal end portion and the sparse distal end portion do not necessarily include the dead coils as the sparse-dense-sparse spring design.

When the torsion spring is tightened, i.e., being wound up, the diameter of each active coil, i.e., the coils that will change shape and therefore store energy, will radially shrink. That is, the diameter of each active coil is reducing during winding the spring.

However, as the dead coil is immovable, the diameter of the dead coil will essentially not change, i.e., the radial shrinking rate is zero, or will only change slightly, i.e., the radial shrinking rate is significantly close to zero compared to other coils, dependent on the engineering tolerances.

Thus, the diameter of the dead coil may be used to determine a final diameter of all coils after the torsion spring is wound up with the predetermined number of windings W.

It should be noted that considering the engineering tolerance, the final diameter of each coil might be closer to the determined final diameter, but not be identical to the determined final diameter. In a typical example, the diameter can be about 5% to10% more or less to the determined final diameter.

Alternatively, in one example where the torsion spring does not comprise a dead coil, the final diameter can be determined by the coil that defines the proximal end of the proximal end portion 42 of the torsion spring and the coil that defines the distal end of the distal end portion 44 of the torsion spring. As these two coils will be the stiffest coils, the shrinking rate will be the least.

In an example of the present disclosure, the “smaller diameter” as mentioned above may be the final diameter, i.e., the diameter of the at least one dead coil or the diameter of the respective end coil. Said diameter is hereinafter referred to as diameter d2.

In this example, the “larger diameter” as mentioned above may be the greatest diameter of active coils in the spring relax configuration, i.e., no accumulated energy. Said diameter is hereinafter referred to as diameter d1 . In one example, where the torsion spring comprises the dead coils, the smaller diameter d2 is the diameter of the dead coils. The shrinking rates of the active coils are dependent on the accumulated energy. In other words, the shrinking rates are dependent on how many windings W the torsion spring is designed to be wound.

The radial shrinking rate of the active coils can be calculated by based on following equations, assuming that the length of the wire that forms the torsion spring is generally constant:

7ir² * 27idl * N = 7ir² * 2nd2 * (TV + W) d2 N dl ~ N + W with N being a number of active coils when the torsion spring is in a relaxed configuration.

It should be noted that the torsion spring may comprise coils with different diameters. However, if the coil with the greatest diameter does not shrink enough, in other words, when the torsion spring is wound up with the predetermined number of windings and there is still a coil having a greater diameter, the coil might shift through other coils, when the edge of the coil is not blocked by the edge of other coils, and thus may cause the spring to jam.

Thus, the shrinking rate is preferably calculated with the greatest diameter of active coils as the larger diameter d1 . In a preferred example, this equation is used to set the final diameter d2.

Furthermore, in some examples, the distal end portion 44 and the proximal end portion 42 may comprises multiple coils with different diameters. The respective diameter of the coils between the coil with the smaller diameter d2 and the coil with the larger diameter d1 may be calculated based on the pitch of those coil, the radial shrinking rate times the larger diameter d1 , an angle between the rotational axis and a tangential line extending from the coil with the smaller diameter d2 and the coil the larger diameter d1 . It should be noted that the exact values of the diameters d1 and d2 as well as and the length of the distal and proximal end portions of the spring and the pitch thereof are dependent on the energy that the spring is designed to accumulate and thus determined by the number of windings W that the spring will be wound.

In one example, L is 9.9 mm, d is 0,9 mm, W is 11 , and N is 22. In one example, L is 4.9 mm, d is 0,7 mm, W is 7, and N is 66.

In one example, between the proximal end portion 42 and the central end portion 43 the torsion spring 4 comprises a first plurality of transition coils (not shown) and between the central portion 43 and the distal end portion 44 the spring comprises a second plurality of transition coils (not shown). The transition coils are configured to match the pitch and/or diameter difference between the portions of the torsion spring.

Additionally or alternatively, in a preferred example, the last coils of the spring 4, i.e. , the free ends of the coil, have straight legs 41 a and 41 b. The straight legs 41 a and 41 b are either tangentially protruding from the last coil, shown in Fig. 4A, or are radially protruding from the last coil, shown in Fig. 4B. Tangential legs are preferred.

The term “straight” refers to the leg essentially protruding only in the plane defined by the respective last coil, i.e., not being bent in in a direction out of said plane.

The straight legs design also avoids the spring from tilting. Moreover, the straight legs design simplifies the manufacturing process, because the only parameter to control is the length of the leg, compared to a hook which has at least one bending radius and at least one length to control.

Furthermore, the straight legs allow for a simplified assembly process in a medicament delivery device, as will be described below.

Still further, the straight legs allow for a better fixation of the last coil and thus further reduces the risk or severeness of the tilt during loading of the spring. In one example, the straight legs are tangential protruding straight legs. The length of the proximal straight leg 41 a and the distal straight leg 41 b is essentially the same.

The straight legs 41 a, 41 b protrude beyond the coils at the distal end and the proximal end of the spring. In a preferred example, the straight legs 41a, 41 b protrude longer than the diameter of the coils at the distal end and the proximal end.

In one example, the straight legs 41 a, 41 b are longer than the smaller diameter d2. The maximum length of the straight legs is limited by the size of the design of the components and/or device, in which the spring is configured to be accommodated.

In an alternative example the pitch and/or diameter is varied from the first to the last coil of the proximal end portion 42 and the distal end portion 44 to match the pitch and diameter of the central portion 43. All other features of this example are the same as discussed above.

Fig. 3 shows a torsion spring according to a second embodiment of the present disclosure. As discussed before, the overall structure of the spring is the same as in the embodiment of Fig. 2, however, the spring also comprises two dead coils 42a at the respective free ends of the spring. Fig. 3 shows the proximal end portion only. The distal end portion is formed accordingly.

Furthermore, Fig. 3 illustrates the use of a spring according to the present disclosure, i.e., of all embodiments and examples discussed above, in a medicament delivery device. Due to the straight leg design, the mating counterpart 22a, i.e., seat, on the respective rotating elements 22 and 23 of the power pack assembly may be simplified compared to the hook counterparts in the state of the art, cf. 23a and 21a in Fig. 1.

The design of the seat 22a can be reduced to an essentially c-shaped protrusion opening in a tangential direction of the rotational part with an inner diameter corresponding to the spring wire diameter d.

Since the wire diameter typically has less tolerance than the bending radius of a hook the fit and thus the fixation of the last coil may be much more precise. This reduces the risk for tilt, as described above. Furthermore, regardless of the initial rotational orientation of the spring, the legs will always find the seat, when the spring and the rotational part 22 comprising the seat 22a are rotated against each other in the opening direction of the seat 22a, preferably when loading the spring.

That is, when the spring and the rotational part are rotated against each other in a rotational direction defined by the c-opening, the legs will be caught by the c opening within one full rotation or less. When the leg is caught in the c-opening the coil may slide some distance during further rotation until the free end is fixed to the rotational part in the seat 22a.

This becomes even more relevant as most springs are heat treated and thus the angle between legs is difficult to control. The spring according to the present disclosure can be assembled regardless of the leg angle because the leg will find the seat within one rotation of the spring relative to the rotational part or less.

Thus, the fixation of the spring is simplified, and the assembly of the medicament delivery device is improved.

Furthermore, since the preferred examples of the spring are symmetrical, the orientation of spring, i.e., orientation of the proximal and distal end portion is not relevant during assembly. In other words, the spring can be assembled regardless of its orientation.

In one example, the c-shaped protrusion further comprises an at least partially inclined surface on a surface opposite of the opening. This inclined surface causes the leg to slip over the c-shaped protrusion when the spring is rotated against the inclined surface. This may further simplify the assembly process.

What has been described in the above with respect to Fig. 3 and the proximal end of the spring is also applicable to the distal end of the spring.

The delivery devices described herein can be used for the treatment and/or prophylaxis of one or more of many different types of disorders. Exemplary disorders include, but are not limited to: rheumatoid arthritis, inflammatory bowel diseases (e.g. Crohn’s disease and ulcerative colitis), hypercholesterolaemia and/or dyslipidemia, cardiovascular disease, diabetes (e.g. type 1 or 2 diabetes), psoriasis, psoriatic arthritis, spondyloarthritis, hidradenitis suppurativa, Sjogren's syndrome, migraine, cluster headache, multiple sclerosis, neuromyelitis optica spectrum disorder, anaemia, thalassemia, paroxysmal nocturnal hemoglobinuria, hemolytic anaemia, hereditary angioedema, systemic lupus erythematosus, lupus nephritis, myasthenia gravis, Behget's disease, hemophagocytic lymphohistiocytosis, atopic dermatitis, retinal diseases (e.g., age-related macular degeneration, diabetic macular edema), uveitis, infectious diseases, bone diseases (e.g., osteoporosis, osteopenia), asthma, chronic obstructive pulmonary disease, thyroid eye disease, nasal polyps, transplant, acute hypoglycaemia, obesity, anaphylaxis, allergies, sickle cell disease, Alzheimer’s disease, Parkinson’s disease, dementia with Lewy bodies, systemic infusion reactions, immunoglobulin E (IgE)-mediated hypersensitivity reactions, cytokine release syndrome, immune deficiencies (e.g., primary immunodeficiency, chronic inflammatory demyelinating polyneuropathy), enzyme deficiencies (e.g., Pompe disease, Fabry disease, Gaucher disease), growth factor deficiencies, hormone deficiencies, coagulation disorders (e.g., hemophilia, von Willebrand disease, Factor V Leiden), and cancer.

Exemplary types of drugs that could be included in the delivery devices described herein include, but are not limited to, small molecules, hormones, cytokines, blood products, enzymes, vaccines, anticoagulants, immunosuppressants, antibodies, antibody-drug conjugates, neutralizing antibodies, reversal agents, radioligand therapies, radioisotopes and/or nuclear medicines, diagnostic agents, bispecific antibodies, proteins, fusion proteins, peptibodies, polypeptides, pegylated proteins, protein fragments, nucleotides, protein analogues, protein variants, protein precursors, protein derivatives, chimeric antigen receptor T cell therapies, cell or gene therapies, oncolytic viruses, or immunotherapies.

Exemplary drugs that could be included in the delivery devices described herein include, but are not limited to, immuno-oncology or bio-oncology medications such as immune checkpoints, cytokines, chemokines, clusters of differentiation, interleukins, integrins, growth factors, coagulation factors, enzymes, enzyme inhibitors, retinoids, steroids, signaling proteins, pro-apoptotic proteins, anti-apoptotic proteins, T-cell receptors, B-cell receptors, or costimulatory proteins.

Exemplary drugs that could be included in the delivery devices described herein include, but are not limited to, those exhibiting a proposed mechanism of action, such as human epidermal growth factor receptor 2 (HER-2) receptor modulators, interleukin (IL) modulators, interferon (IFN) modulators, complement modulators, glucagon-like peptide-1 (GLP-1) modulators, glucose-dependent insulinotropic polypeptide (GIP) modulators, cluster of differentiation 38 (CD38) modulators, cluster of differentiation 22 (CD22) modulators, C1 esterase modulators, bradykinin modulators, C-C chemokine receptor type 4 (CCR4) modulators, vascular endothelial growth factor (VEGF) modulators, B-cell activating factor (BAFF), P- selectin modulators, neonatal Fc receptor (FcRn) modulators, calcitonin gene-related peptide (CGRP) modulators, epidermal growth factor receptor (EGFR) modulators, cluster of differentiation 79B (CD79B) modulators, tumor-associated calcium signal transducer 2 (Trop-2) modulators, cluster of differentiation 52 (CD52) modulators, B- cell maturation antigen (BCMA) modulators, enzyme modulators, platelet-derived growth factor receptor A (PDGFRA) modulators, cluster of differentiation 319 (CD319 or SLAMF7) modulators, programmed cell death protein 1 and programmed deathligand 1 (PD-1/PD-L1) inhibitors/modulators, B-lymphocyte antigen cluster of differentiation 19 (CD19) inhibitors, B-lymphocyte antigen cluster of differentiation 20 (CD20) modulators, cluster of differentiation 3 (CD3) modulators, cytotoxic T- lymphocyte-associated protein 4 (CTLA-4) inhibitors, T-cell immunoglobulin and mucin-domain containing-3 (TIM-3) modulators, T cell immunoreceptor with Ig and ITIM domains (TIGIT) modulators, V-domain Ig suppressor of T cell activation (VISTA) modulators, indoleamine 2,3-dioxygenase (IDO or INDO) modulators, poliovirus receptor-related immunoglobulin domain-containing protein (PVRIG) modulators, lymphocyte-activation gene 3 (LAG3; also known as cluster of differentiation 223 or CD223) antagonists, cluster of differentiation 276 (CD276 or B7-H3) antigen modulators, cluster of differentiation 47 (CD47) antagonists, cluster of differentiation 30 (CD30) modulators, cluster of differentiation 73 (CD73) modulators, cluster of differentiation 66 (CD66) modulators, cluster of differentiation w137 (CDw137) agonists, cluster of differentiation 158 (CD158) modulators, cluster of differentiation 27 (CD27) modulators, cluster of differentiation 58 (CD58) modulators, cluster of differentiation 80 (CD80) modulators, cluster of differentiation 33 (CD33) modulators, cluster of differentiation 159 (CD159 or NKG2) modulators, glucocorticoid-induced TNFR-related (GITR) protein modulators, Killer Ig-like receptor (KIR) modulators, growth arrest-specific protein 6 (GAS6)/AXL pathway modulators, A proliferation-inducing ligand (APRIL) receptor modulators, human leukocyte antigen (HLA) modulators, epidermal growth factor receptor (EGFR) modulators, B-lymphocyte cell adhesion molecule modulators, cluster of differentiation w123 (CDw123) modulators, Erbb2 tyrosine kinase receptor modulators, endoglin modulators, mucin modulators, mesothelin modulators, hepatitis A virus cellular receptor 2 (HAVCR2) antagonists, cancer-testis antigen (CTA) modulators, tumor necrosis factor receptor superfamily, member 4 (TNFRSF4 or 0X40) modulators, adenosine receptor modulators, inducible T cell co-stimulator (ICOS) modulators, cluster of differentiation 40 (CD40) modulators, tumor-infiltrating lymphocytes (TIL) therapies, or T-cell receptor (TCR) therapies.

Exemplary drugs that could be included in the delivery devices described herein include, but are not limited to: etanercept, abatacept, adalimumab, evolocumab, exenatide, secukinumab, erenumab, galcanezumab, fremanezumab-vfrm, alirocumab, methotrexate (amethopterin), tocilizumab, interferon beta-1 a, interferon beta-1 b, peginterferon beta-1 a, sumatriptan, darbepoetin alfa, belimumab, sarilumab, semaglutide, dupilumab, reslizumab, omalizumab, glucagon, epinephrine, naloxone, insulin, amylin, vedolizumab, eculizumab, ravulizumab, crizanlizumab- tmca, certolizumab pegol, satralizumab, denosumab, romosozumab, benralizumab, emicizumab, tildrakizumab, ocrelizumab, ofatumumab, natalizumab, mepolizumab, risankizumab-rzaa, ixekizumab, and immune globulins.

Exemplary drugs that could be included in the delivery devices described herein may also include, but are not limited to, oncology treatments such as ipilimumab, nivolumab, pembrolizumab, atezolizumab, durvalumab, avelumab, cemiplimab, rituximab, trastuzumab, ado-trastuzumab emtansine, fam-trastuzumab deruxtecan- nxki, pertuzumab, transtuzumab-pertuzumab, alemtuzumab, belantamab mafodotin- blmf, bevacizumab, blinatumomab, brentuximab vedotin, cetuximab, daratumumab, elotuzumab, gemtuzumab ozogamicin, 90-Yttrium-ibritumomab tiuxetan, isatuximab, mogamulizumab, moxetumomab pasudotox, obinutuzumab, ofatumumab, olaratumab, panitumumab, polatuzumab vedotin, ramucirumab, sacituzumab govitecan, tafasitamab, or margetuximab.

Exemplary drugs that could be included in the delivery devices described herein include “generic” or biosimilar equivalents of any of the foregoing, and the foregoing molecular names should not be construed as limiting to the “innovator” or “branded” version of each, as in the non-limiting example of innovator medicament adalimumab and biosimilars such as adalimumab-afzb, adalimumab-atto, adalimumab-adbm, and adalimumab-adaz.

Exemplary drugs that could be included in the delivery devices described herein also include, but are not limited to, those used for adjuvant or neoadjuvant chemotherapy, such as an alkylating agent, plant alkaloid, antitumor antibiotic, antimetabolite, or topoisomerase inhibitor, enzyme, retinoid, or corticosteroid. Exemplary chemotherapy drugs include, by way of example but not limitation, 5-fluorouracil, cisplatin, carboplatin, oxaliplatin, doxorubicin, daunorubicin, idarubicin, epirubicin, paclitaxel, docetaxel, cyclophosphamide, ifosfamide, azacitidine, decitabine, bendamustine, bleomycin, bortezomib, busulfan, cabazitaxel, carmustine, cladribine, cytarabine, dacarbazine, etoposide, fludarabine, gemcitabine, irinotecan, leucovorin, melphalan, methotrexate, pemetrexed, mitomycin, mitoxantrone, temsirolimus, topotecan, valrubicin, vincristine, vinblastine, or vinorelbine.

Exemplary drugs that could be included in the delivery devices described herein also include, but are not limited to, analgesics (e.g., acetaminophen), antipyretics, corticosteroids (e.g. hydrocortisone, dexamethasone, or methylprednisolone), antihistamines (e.g., diphenhydramine or famotidine), antiemetics (e.g., ondansetron), antibiotics, antiseptics, anticoagulants, fibrinolytics (e.g., recombinant tissue plasminogen activator [r-TPA]), antithrombolytics, or diluents such as sterile water for injection (SWFI), 0.9% Normal Saline, 0.45% normal saline, 5% dextrose in water, 5% dextrose in 0.45% normal saline, Lactated Ringer’s solution, Heparin Lock Flush solution, 100 U/mL Heparin Lock Flush Solution, or 5000 U/mL Heparin Lock Flush Solution. Pharmaceutical formulations including, but not limited to, any drug described herein are also contemplated for use in the delivery devices described herein, for example pharmaceutical formulations comprising a drug as listed herein (or a pharmaceutically acceptable salt of the drug) and a pharmaceutically acceptable carrier. Such formulations may include one or more other active ingredients (e.g., as a combination of one or more active drugs), or may be the only active ingredient present, and may also include separately administered or co-formulated dispersion enhancers (e.g., an animal-derived, human-derived, or recombinant hyaluronidase enzyme), concentration modifiers or enhancers, stabilizers, buffers, or other excipients.

Exemplary drugs that could be included in the delivery devices described herein include, but are not limited to, a multi-medication treatment regimen such as AC, Dose-Dense AC, TCH, GT, EC, TAC, TC, TCHP, CMF, FOLFOX, mFOLFOX6, mFOLFOX7, FOLFCIS, CapeOx, FLOT, DCF, FOLFIRI, FOLFIRINOX, FOLFOXIRI, IROX, CHOP, R-CHOP, RCHOP-21 , Mini-CHOP, Maxi-CHOP, VR-CAP, Dose- Dense CHOP, EPOCH, Dose-Adjusted EPOCH, R-EPOCH, CODOX-M, IVAC, HyperCVAD, R-HyperCVAD, SC-EPOCH-RR, DHAP, ESHAP, GDP, ICE, MINE, CEPP, CDOP, GemOx, CEOP, CEPP, CHOEP, CHP, GCVP, DHAX, CALGB 8811 , HIDAC, MOpAD, 7 + 3, 5 +2, 7 + 4, MEC, CVP, RBAC500, DHA-Cis, DHA-Ca, DHA- Ox, RCVP, RCEPP, RCEOP, CMV, DDMVAC, GemFLP, ITP, VIDE, VDC, VAI, VDC-IE, MAP, PCV, FCR, FR, PCR, HDMP, OFAR, EMA/CO, EMA/EP, EP/EMA, TP/TE, BEP, TIP, VIP, TPEx, ABVD, BEACOPP, AVD, Mini-BEAM, IGEV, C-MOPP, GCD, GEMOX, CAV, DT-PACE, VTD-PACE, DCEP, ATG, VAC, VelP, OFF, GTX, CAV, AD, MAID, AIM, VAC-IE, ADOC, or PE.

Various modifications to the embodiments and examples described are possible and will occur to those skilled in the art without departing from the invention which is defined by the following claims.

Claims

1 . A torsion spring (4) for use in a medicament delivery device, wherein the torsion spring (4) is formed from a wire with a diameter d, wherein the torsion spring (4) is configured to rotate around a rotational axis of a mandrel of the medicament delivery device and to store a predetermined amount of energy, when wound a predetermined number of windings, W, around the rotational axis; wherein the torsion spring (4) comprises: at least a distal end portion (44), a central portion (43), and proximal end portion (42); and wherein the distal end portion (44), the central portion (43), and the proximal end portion (42) are formed essentially next to each other with respect the mandrel of the medicament delivery device.

2. The torsion spring according to claim 1 , wherein the torsion spring consists of the distal end portion, the central portion, and the proximal end portion.

3. The torsion spring according to claim 1 or claim 2, wherein the torsion spring (4) further comprises free ends formed as a straight leg (41a, 41 b) essentially protruding only in a plane defined by a respective last coil of the torsion spring (4).

4. The torsion spring according to any one of claims 1 to 3, wherein coils of the central portion (43) have a first uniform pitch; and wherein coils of the distal end portion (44) and the proximal end portion (42) each have a pitch higher than the first uniform pitch.

5. The torsion spring according to any one of claims 1 to 4, wherein the distal end portion (44) has a second uniform pitch; wherein the proximal end portion (42) has a third uniform pitch; and wherein the second uniform pitch and the third uniform pitch are preferably a same pitch.

6. The torsion spring according to any one of claims 1 to 5, wherein the coils of the central portion (43) have essentially zero pitch.

7. The torsion spring according to any one of claims 1 to 6, wherein a length L is the sum of a total length, measured along the rotational axis, of the distal end portion (44) and the proximal end portion (42) and is calculated the diameter of the wire d times the predetermined number of windings W.

8. The torsion spring according to claim 7, wherein length L is essentially evenly distributed to the proximal end portion (42) and the distal end portion (44).

9. The torsion spring according to any one of claims 1 to 8, further comprising at least one dead coil with essentially zero pitch at the distal end of the torsion spring (4) and at the proximal end of the torsion spring (4), respectively; and preferably comprising two dead coils at each end of the torsion spring (4).

10. The torsion spring according to claim 9, wherein the at least one dead coil has diameter, d2, defining a final diameter of all coils of the torsion spring (4) after the torsion spring (4) is wound up with the predetermined number of windings W.

11 . The torsion spring according to any one of claims 1 to 10, wherein the coils of the central portion (43) have a first uniform diameter, d1 , and wherein the ratio of the diameter of the at least one dead coil, d2, and the first uniform diameter is calculated by: d.2 N dl ~ N + W with N being a number of active coils, when the torsion spring (4) is not wound.

12. The torsion spring according to claim 11 , wherein the coils of the distal end portion (44) and the proximal end portion (42) each have diameter smaller than the first uniform diameter.

13. The torsion spring according to any one of claims 1 to 12, wherein the straight legs (41 a, 41 b) are protruding in a tangential direction of the respective last coil; or wherein the straight legs (41 a, 41 b) are protruding in a radial direction of the respective last coil.

14. A medicament delivery device with a torsion spring according to any one of claims 1 to 13, wherein the medicament delivery device comprises a power pack assembly with at least a proximal rotational part and a distal rotational part, each rotational part with a respective seat for holding the torsion spring; wherein torsion spring has tangential straight legs; and wherein the seats are essentially c-shaped protrusions opening in a tangential direction of the rotational parts in a direction against the rotation of the spring during winding.

15. The medicament delivery device according to claim 14, when dependent upon claim 10, wherein the diameter d2 of the dead coil is essentially the diameter of a mandrel of the medicament delivery device.