Patent Description:
Some medications are designed to be delivered via injection by a doctor, nurse, or other care provider at a care center. Other medications are indicated to be delivered via injection at home. Whether the person injecting the medication has substantial experience injecting medications that provide resistance to depressing the plunger or a patient or some other person who lacks such experience, it can be therefore desirable to provide an injection training device that simulates the tactile sensations of injecting a high-viscosity medication. Such an injection training device can allow the user to draw from his or her experience gained operating the injection training device when it comes time to deliver the medication through a syringe and needle. <CIT> describes a plunger speed control training system and method. <CIT> describes a locking member for an injection device and an injection device trainer. <CIT> describes an automatic injection training device.

In one example, according to the claimed invention, an injection training device includes a barrel, and a first assembly that includes a plunger and a damper housing coupled to the plunger. The first assembly is translatable with respect to the barrel. The injection training device further includes a second assembly including a rotor, such that a damper chamber is defined between the rotor and the damper housing. A viscous fluid is disposed in the damper chamber. Translation of the first assembly causes a force to be applied to the rotor that causes the rotor to rotate about an axis of rotation with respect to the damper housing. The viscous fluid resists rotation of the rotor about the axis with respect to the damper housing.

In another example, a method of operating an injection training device can include the step of depressing a plunger in a distal direction with respect to a barrel, thereby causing the plunger to apply a force to a rotor that drives the rotor to travel in the distal direction. The method can further include, in response to the depressing step, rotating the rotor within a damper housing in a first direction of rotation about an axis, and providing a rotational counterforce to the rotation of the rotor with a viscous fluid disposed in a damper chamber between the rotor and the damper housing.

The following detailed description will be better understood when read in conjunction with the appended drawings, in which there is shown in the drawings example embodiments for the purposes of illustration. It should be understood, however, that the present disclosure is not limited to the precise arrangements and instrumentalities shown. In the drawings:.

Referring initially to <FIG>, an injection training device <NUM> is configured to simulate the tactile sensations and forces associated with the operation of a corresponding injection device that delivers a medication to a patient. The injection training device <NUM> includes a barrel <NUM> and a plunger <NUM> that is configured to be depressed in a distal direction from an initial or undeployed position shown in <FIG> to a final or deployed position shown in <FIG>. It is appreciated that the barrel of an injection device typically contains a medication that is delivered from the barrel to a needle or other suitable delivery member. However, the barrel of the injection training device <NUM> does not contain medication in some examples. Rather, the injection training device <NUM> is configured to simulate operation of an injection device without actually delivering medication.

The barrel <NUM> defines a proximal end 22a and a distal end 22b. The distal end 22b can define a simulated Luer lock connection <NUM>. In this regard, it is recognized that injection devices typically include a needle, infusion set, or the like, that is attached to a barrel via a Luer lock. However, the simulated Luer lock connection <NUM> is not configured to attach to a needle, infusion set, or the like, but rather simulates the look of a Luer lock of the corresponding injection device. Alternatively, the injection training device <NUM> can include a simulated needle that extends out from the distal end 22b of the barrel <NUM>, or any suitable alternative structure that extends out from the distal end 22b. Recognizing that the simulated Leur lock, simulated needle, or other structure that extends out from the distal end 22b primarily provides aesthetics, it is recognized that the injection training device <NUM> can alternatively be devoid of structure that extends out from the distal end 22b.

As will be appreciated from the description below, the injection training device <NUM> is configured to provide resistance to the depression of the plunger <NUM>. The resistance to the depression of the plunger at a constant predetermined rate can be substantially equal to the resistance that a user will experience when delivering a medication from the corresponding injection device at the constant predetermined rate. Examples of the injection training device <NUM> can be configured to simulate a large volume subcutaneous injection. For instance, embodiments of the injection training device <NUM> can be configured to simulate the injection of a Darzalex Faspro™ (daratumumab and hyaluronidase-fihj) subcutaneous formulation marketed by Janssen Pharmaceuticals, Inc. having a place of business in Raritan, NJ. It will be appreciated from the description below, however, that the injection training device <NUM> can be tuned to simulate delivery of other medications.

In one example, the desired stroke time to move the plunger from the initial or undeployed position to the final or deployed position can be in the range of approximately <NUM> minutes to approximately <NUM> minutes, such as approximately <NUM> minutes, though any suitable alternative stroke time can be achieved as desired. It is appreciated, however, that the user of the injection training device <NUM> can apply any suitable force as desired to depress the plunger. Further, the user of the injection training device <NUM> can depress the plunger over a range of possible time durations that can be the same as that to fully deliver the dosage of medication from the corresponding injection device, or different than that to fully deliver the dosage of medication from the corresponding injection device. The injection training device <NUM> provides the user with tactile feedback so as to allow the user to practice depressing the plunger at the constant predetermined rate that will allow the medication to be delivered to the patient from the corresponding injection device at a rate is designed to fully deliver the medication efficiently but with minimal pain to the patient. The corresponding injection device can include any suitable volume of medication in its barrel as desired, such as approximately <NUM>.

Ergonomically, the injection training device <NUM> is designed to simulate the corresponding injection device. For instance, the injection training device <NUM> can include a barrel flange <NUM> that extends out from the proximal end 22a of the barrel <NUM>, and a plunger flange <NUM> that extends out from a proximal end of the plunger <NUM>. The user can brace his or her fingers against the barrel flange <NUM> as the user applies a deployment force to the plunger <NUM> via his or her thumb in a distal direction, and in particular to the plunger flange <NUM>, that drives the plunger to translate in the distal direction. Each of the components of the injection training device <NUM> defines a proximal end and a distal end that is opposite the proximal end in the distal direction. Further, the proximal end of each of the components is spaced from the distal end in a proximal direction that is opposite the distal direction.

Referring now to <FIG>, the components of the injection training device <NUM> will now be described. In particular, the injection training device <NUM> includes the barrel <NUM> and the plunger <NUM> as described above. The injection training device <NUM> further includes a damper housing <NUM> and a rotor <NUM> that is designed to rotate in the damper housing <NUM> about an axis of rotation <NUM> that is oriented in the proximal and distal directions. The injection training device <NUM> can further include a rotor cap <NUM> that is configured to attach to the rotor <NUM>, for instance at the proximal end of the rotor <NUM>. The injection training device <NUM> can further include a rotor retainer cap <NUM> that is configured to attach to the damper housing <NUM> and a sealing gasket <NUM> that are configured to seal an interface between the rotor retainer cap <NUM> and the rotor <NUM>. The injection training device <NUM> can further include a shaft <NUM> that is configured to be supported in the barrel <NUM>, and a clutch <NUM> that is configured to mate with the shaft <NUM> and engage the rotor <NUM>. In one example, the shaft <NUM> can be configured as a threaded shaft that is threadedly mated with the clutch <NUM>. For instance, the clutch <NUM> can rotatably fix to the rotor <NUM>. The injection training device <NUM> can further include a damper housing cap <NUM> that is configured to extend in the distal direction from the rotor retainer cap <NUM>. The injection training device <NUM> can further include a biasing member <NUM>, such as a coil spring, an elastomer, or the like, that extends from the damper housing cap <NUM> to the clutch <NUM>, and can bias the clutch <NUM> against the distal end of the rotor <NUM>.

It is recognized that each of the components of the injection training device <NUM> can be configured as annular components that surround the axis <NUM> that can be said to extend along an axial direction. The axial direction can include both the proximal direction and the distal direction. Further, it should be appreciated that while the components of the injection training device <NUM> have been described as separate components, some of the components can instead define a single monolithic component. Conversely, while some of the components have been described as single unitary components, the components can alternatively be defined by two separate components that are attached to each other.

Referring now to <FIG>, the barrel <NUM> defines an internal barrel void <NUM>, and the plunger <NUM> defines an internal plunger void <NUM>. The damper housing <NUM> can extend into each of the internal barrel void <NUM> and the internal plunger void <NUM> when the plunger is in the undeployed position. The internal barrel void <NUM> can be disposed distal of the internal plunger void <NUM>. The plunger <NUM> can extend out from the barrel void <NUM> in the undeployed position, and is configured to translate in the distal direction in the internal barrel void <NUM> toward the deployed position. The plunger <NUM> can define an annular plunger body <NUM>, and a handle portion <NUM> that extends from the plunger body in the proximal direction. The plunger flange <NUM> can extend radially out from the proximal end of the handle portion <NUM>.

The damper housing <NUM> can be disposed in the annular plunger body <NUM>. The damper housing <NUM> can be configured as an annular body having a radially outer surface 32a and a radially inner surface 32b that is opposite the radially outer surface 32a. The radially inner surface 32b can face the rotor <NUM>. A proximal portion of the radially outer surface 32a can face a radially inner wall of the plunger body <NUM>, and a distal portion of the radially outer surface 32a can face a radially inner wall of the barrel <NUM>. In this regard, the injection training device <NUM> can define a radially outward direction that extends away from the axis <NUM>, and a radially inward direction that extends toward the axis <NUM>. The damper housing <NUM> can be translatably coupled to the plunger <NUM>, such that the damper housing <NUM> travels along with the plunger <NUM> in each of the distal direction and in the proximal direction.

The rotor <NUM> can be at least partially or entirely disposed in the damper housing <NUM>. The rotor <NUM> defines a radially outer wall <NUM> having a radially outer surface <NUM> that faces the radially inner surface 32b of the damper housing <NUM>. The rotor <NUM> is configured to rotate with respect to the damper housing <NUM> about the axis <NUM>. For instance, when the plunger <NUM> is depressed in the distal direction, the rotor rotates about the axis <NUM> in a first direction of rotation. The injection training device <NUM> can include a rotor cap <NUM> that is configured to be attached to the rotor <NUM> so as to rotate with the rotor <NUM>. The rotor cap <NUM> defines a proximal facing surface that abuts a distal facing surface on the proximal side of the damper housing <NUM>. In one example, the proximal facing surface can be tapered as it extends in the proximal direction so as to define a point contact with the damper housing <NUM>, thereby facilitating rotation of the rotor <NUM> with respect to the damper housing <NUM>. In particular, the rotor cap <NUM>, and thus the rotor <NUM> which is rotatably fixed to the rotor cap <NUM>, can rotate with respect to the damper housing <NUM> about the point contact defined at the interface between the rotor cap <NUM> and the damper housing <NUM>.

Referring also to <FIG>, a damper chamber <NUM> is disposed between the outer surface <NUM> of the rotor <NUM> and the inner surface 32b of the damper housing <NUM> along a direction that is perpendicular to the axis <NUM>. The direction perpendicular to the axis <NUM> can also be referred to as a radial direction in some examples. It is also envisioned that at least some of the components of the injection training device <NUM> define shapes that define lateral and transverse directions that are perpendicular to each other and perpendicular to the axis <NUM> which can be said to extend along a longitudinal direction. Thus, the radially outward and inward directions as described herein can alternatively be expressed as directions away from and toward, respectively, the axis <NUM> along one or both of the lateral direction and the transverse direction.

A viscous fluid <NUM> can be disposed in the damper chamber <NUM> that resists rotation of the rotor <NUM> with respect to the damper housing <NUM> about the axis <NUM>. Further, the rotor <NUM> can have a textured radially outer surface <NUM> that faces the damper housing <NUM>, and in particular faces the radially inner surface 32b of the damper housing <NUM>. Thus, the textured surface <NUM> can at least partially define the damper chamber <NUM>. The textured surface <NUM> defines variable distances from the radially outer surface of the rotor <NUM> to the radially inner surface 32b of the damper housing <NUM> along the radial direction. As the rotor <NUM> is driven to rotate with respect to the damper housing <NUM> about the axis <NUM>, the viscous fluid <NUM> interferes with the motion of the textured surface <NUM>, thereby further impeding rotation of the rotor <NUM>. The textured radially outer surface <NUM> can include a plurality of knurls <NUM> that project radially outward toward the radially inner surface 32b of the damper housing <NUM>. The knurls <NUM> can be spaced from each other along a plane that is oriented perpendicular to the axis <NUM>. Thus, the knurls <NUM> can be circumferentially spaced from each other. The knurls <NUM> can further be oriented along a direction parallel to the axis <NUM>. The rotor cap <NUM> can define a textured outer surface as described above with respect to the rotor <NUM>.

Thus, the radially outer surface <NUM> of the rotor <NUM> can be textured and the radially inner surface 32b of the damper housing can be smooth in one example. Alternatively, the radially inner surface 32b of the damper housing can be textured such as knurled as described above with respect to the rotor <NUM>, and the radially outer surface <NUM> of the rotor <NUM> can be smooth. Alternatively still, both the radially outer surface <NUM> of the rotor <NUM> and the radially inner surface 32b of the damper housing can both be textured, such as knurled, as described above with respect to the rotor.

Referring now to <FIG>, the rotor <NUM> can define an annular void <NUM> that extends into the distal end of the outer wall <NUM> along a proximal direction. Thus, the rotor <NUM> can define a radially inner wall <NUM> and the radially outer wall <NUM> that are radially separated from each other by the annular void <NUM>. The radially inner wall <NUM> is spaced from the radially outer wall <NUM> in the radially inward direction. Further, the radially inner wall <NUM> can extend distally past the radially outer wall <NUM>. The annular void <NUM> can be disposed at a distal portion of the rotor <NUM>. The outer surface <NUM> at the distal portion of the rotor <NUM> can be radially outwardly offset with respect to the outer surface <NUM> at the proximal portion of the rotor <NUM>. In this regard, the outer surface <NUM> of the rotor <NUM> can be substantially aligned with the radially outer surface of the plunger <NUM>.

The rotor <NUM> is operably coupled to the threaded shaft <NUM>, such that a force applied to the rotor <NUM> in the distal direction causes the rotor <NUM> to rotate in the first direction of rotation about the axis <NUM>. In particular, referring also to <FIG>, the threaded shaft <NUM> has an outer surface <NUM> that defines at least one thread <NUM>. The at least one thread can be a helical thread. The clutch <NUM> further defines at least one thread <NUM> that is threadedly mated with the threaded shaft <NUM>. Thus, the clutch <NUM> travels along the at least one thread <NUM> as the clutch travels in each of the proximal direction and the distal direction. Thus, when a force is applied to the clutch <NUM> in the distal direction, the clutch <NUM> rotates in a first direction of rotation about the axis <NUM> as the shaft travels along the threaded shaft <NUM>. When a force is applied to the clutch <NUM> in the proximal direction, the clutch <NUM> rotates in a second direction of rotation about the axis <NUM> as the shaft travels along the threaded shaft <NUM> in the proximal direction. The second direction of rotation is opposite the first direction of rotation.

It should be appreciated that while the clutch <NUM> is shown threadedly mated to the shaft <NUM>, other variations are contemplated that cause the clutch <NUM> to rotate as it travels in the distal direction, and in the proximal direction. For instance, the radially outer surface of the clutch <NUM> can alternatively threadedly mate with a thread that is supported by the radially inner surface of the barrel <NUM>. The device does not include the shaft <NUM> that extends through the barrel void <NUM> of the barrel <NUM> in this example. The internal barrel void <NUM> can contain a medication or other drug to be delivered to a patient. In this regard, a needle can be attached to the distal end of the barrel <NUM> using a Leur lock or the like in the traditional manner. The damper housing cap <NUM>, rotor retainer cap <NUM>, damper housing <NUM>, or any suitable alternative structure can include a stopper at its distal end that travels in the distal direction in the barrel void <NUM> as the plunger <NUM> is depressed in the distal direction. Thus, depression of the plunger <NUM> in the distal direction causes stopper to drive the medication from the internal barrel void <NUM> into the needle. The medication can thus be delivered to a patient via the needle. Accordingly, it is appreciated that the device <NUM> can be configured as an injection training device as described above, or can alternatively be configured as an injection device in some examples.

Referring now also to <FIG>, the clutch <NUM> is rotatably engaged with the rotor <NUM> in the first direction of rotation. Accordingly, rotation of the clutch <NUM> in the first direction of rotation drives the rotor <NUM> to rotate with the clutch <NUM> in the first direction of rotation. In particular, the clutch <NUM> can define at least one tooth <NUM> such as a plurality of teeth <NUM>. The teeth <NUM> can extend from a surface of the clutch <NUM> in the proximal direction. In one example, the teeth <NUM> can extend from a proximal end of the clutch <NUM>. Similarly, the rotor can define at least one tooth <NUM> such as a plurality of teeth <NUM> that are configured to engage the at least one tooth <NUM> of the clutch <NUM>. The teeth <NUM> can extend from the distal end of the inner wall <NUM> of the rotor <NUM> in the distal direction. The teeth <NUM> and <NUM> can be configured to engage each other in the first direction of rotation. Thus, when the clutch <NUM> is driven to rotate in the first direction of rotation, the teeth <NUM> and <NUM> mate, and can interdigitate with each other, so as to rotatably fix the rotor <NUM> to the clutch <NUM>. Therefore, as the clutch <NUM> rotates in the first direction of rotation, the rotor <NUM> rotates with the clutch <NUM> in the first direction of rotation.

With continuing reference to <FIG>, at least one or both of the teeth <NUM> and <NUM> can be angled to ride past each other when the clutch rotates in the second direction of rotation. For instance, the teeth <NUM> of the rotor <NUM> and the teeth <NUM> of the clutch <NUM> can be sloped in the proximal direction as they extend in the second direction of rotation. Thus, the clutch <NUM> can be rotatably disengaged from the rotor <NUM> in the second direction of rotation, such that rotation of the clutch <NUM> in the second direction of rotation does not drive the rotor <NUM> to rotate in the second direction of rotation. Thus, the rotor can travel in the proximal direction without being driven by the clutch to rotate about the axis <NUM>. In one example, the teeth <NUM> and <NUM> can slide along each other as the clutch is rotated in the second direction of rotation, thereby providing audible and/or tactile feedback to the user to indicate that the clutch is rotating in the second direction of rotation. Alternatively, the teeth <NUM> and <NUM> can be configured to rotatably fix to each other, such that the rotor <NUM> rotates with the clutch <NUM> in the second direction of rotation about the axis <NUM>.

Referring again to <FIG>, the clutch <NUM> can be biased into engagement with the rotor <NUM> such that the clutch <NUM> abuts the rotor <NUM>. In particular, the teeth <NUM> of the clutch <NUM> can abut the teeth <NUM> of the rotor <NUM>. The injection training device <NUM> can include a biasing member <NUM> that provides a force against the clutch <NUM> in the proximal direction, thereby urging the clutch <NUM> into abutment with the rotor <NUM>. Alternatively, the biasing member can bias the rotor <NUM> distally against the clutch <NUM>. The biasing member <NUM> can be configured as a spring, such as a coil spring, an elastomer, or can be configured in accordance with any suitable alternative embodiment.

The biasing member <NUM> can be seated against any suitable spring seat <NUM> as desired. For instance, the injection training device <NUM> can include a damper housing cap <NUM> that defines the spring seat <NUM> in one example. The damper housing cap <NUM> can define an annular body <NUM> that defines a radially outer surface 63a and a radially inner surface 63b opposite the radially outer surface 63a. The damper housing cap <NUM> can be attached to the damper housing <NUM>. For instance, the radially outer surface 63a of the damper housing cap <NUM> can be attached to the radially inner surface 32b of the damper housing <NUM>. Thus, the damper housing cap <NUM> travels with the damper housing <NUM> in each of the proximal direction and the distal direction. In the event that the damper housing cap <NUM> and the damper housing <NUM> are metallic, the damper housing cap <NUM> can be welded to the damper housing <NUM>. It should be appreciated that the damper housing cap <NUM> can be alternatively attached to the damper housing <NUM> as desired. The damper housing cap <NUM> can include the spring seat <NUM> that extends radially inward from the radially inner surface 63b of the damper housing cap <NUM>. The spring seat <NUM> can be a proximal facing surface. The biasing member <NUM> can therefore be captured between the spring seat <NUM> and the clutch <NUM> in a compressed configuration, such that the biasing member <NUM> applies a force to the clutch <NUM> that biases the clutch <NUM> in the proximal direction. In some examples, the biasing member biases the clutch <NUM> against the rotor <NUM> such that the respective teeth <NUM> and <NUM> contact each other in the manner described above.

With continuing reference to <FIG>, the injection training device <NUM> is configured to seal the damper chamber <NUM> (see also <FIG>). In particular, the injection training device <NUM> can include a rotor retainer cap <NUM> and a sealing gasket <NUM> that in combination prevent the viscous fluid <NUM> from leaking out of the damper chamber <NUM>, and thus retain the viscous fluid <NUM> in the damper chamber <NUM>. The rotor retainer cap <NUM> can be attached to the damper housing <NUM>. For instance, the rotor retainer cap <NUM> can be attached to the damper housing <NUM> at a location distal of the damper chamber <NUM> and proximal of the damper housing cap <NUM>. In one example, the rotor retainer cap <NUM> can be attached to the radially inner surface 32b of the damper housing <NUM>. In the event that the rotor retainer cap <NUM> and the damper housing <NUM> are metallic, the rotor retainer cap <NUM> can be welded to the damper housing <NUM>. It should be appreciated that the rotor retainer cap <NUM> can be alternatively attached to the damper housing <NUM> as desired. The rotor retainer cap <NUM> can travel with the damper housing <NUM> in each of the proximal direction and the distal direction.

In one example, the rotor retainer cap <NUM> can define a base <NUM> and an annular arm <NUM> that extends in the proximal direction from the base <NUM>. The rotor retainer cap <NUM> can extend into the rotor <NUM> in the proximal direction. In particular, the arm <NUM> can extend into the annular void <NUM> of the rotor <NUM>. The arm <NUM> can be radially spaced from the radially outer wall <NUM> and the radially inner wall <NUM> of the rotor <NUM>, such that the rotor retainer cap <NUM> does not impede rotation of the rotor <NUM> during operation. The base <NUM> can be attached to the damper housing <NUM> in the manner described above. Thus, the viscous fluid in the damper chamber <NUM> is unable to flow in the distal direction from the damper chamber <NUM> through the interface between the rotor retainer cap <NUM> and the damper housing <NUM>. The rotor retainer cap <NUM> can define a flange <NUM> that extends out from the base <NUM>. The flange <NUM> can extend in the distal direction from the base <NUM> at a location radially inwardly spaced from the barrel <NUM>, and radially outwardly spaced from the radially inner wall <NUM> of the rotor <NUM>. The clutch <NUM> can include a finger <NUM>, which can be an annular finger <NUM>, that extends to a location between the rotor retainer cap <NUM> and the rotor <NUM>. For instance, the finger <NUM> can extend to a location radially between the flange <NUM> and the rotor <NUM>. In one example, the finger <NUM> can extend in the proximal direction to the location radially between the flange <NUM> and the rotor <NUM>, and in particular the inner rotor wall <NUM>. The finger <NUM> can be disposed radially outward with respect to the teeth <NUM> of the clutch <NUM>.

Alternatively or additionally, the damper housing cap <NUM> can be attached to the rotor retainer cap <NUM>. For instance, the proximal end of the damper housing cap <NUM> can be attached to one or both of the base <NUM> and the flange <NUM> of the rotor retainer cap <NUM>. In one example, for instance when the rotor retainer cap <NUM> and the damper housing cap <NUM> and <NUM> are metallic, the rotor retainer cap <NUM> and the damper housing cap <NUM> can be welded to each other. Whether the damper housing cap <NUM> is attached to the rotor retainer cap <NUM>, the damper housing <NUM>, or both, the damper housing cap <NUM>, the rotor retainer cap <NUM>, and the damper housing <NUM> are all translatably and rotationally fixed to each other.

Referring also to <FIG>, the injection training device <NUM> can further include a sealing gasket <NUM> that seals an interface between the rotor retainer cap <NUM> and the rotor <NUM>. The sealing gasket <NUM> is configured to prevent the viscous fluid <NUM> from leaking out of the damper chamber <NUM> at the interface between the rotor retainer cap <NUM> and the rotor <NUM>. The sealing gasket <NUM> can include a ring-shaped body <NUM> (see also <FIG>) that extends radially from the flange <NUM> of the rotor retainer cap <NUM> to the radially inner wall <NUM> of the rotor <NUM>, thereby sealing the interface between the base <NUM> and the radially inner wall <NUM> with respect to the viscous fluid <NUM> that is disposed in the damper chamber <NUM>. Accordingly, the rotor retainer cap <NUM> in combination with the sealing gasket <NUM> effectively seal the viscous fluid <NUM> in the damper chamber <NUM> during operation of the injection training device <NUM>. The sealing gasket <NUM> can be under constant compression between the radially inner surface of the rotor retainer cap <NUM> and the radially outer surface of the rotor <NUM>. The sealing gasket <NUM> can further include a plurality of localized bumps <NUM> that project from the body <NUM> in the distal direction. The localized bumps <NUM> can make point contact with the finger <NUM> of the clutch <NUM>. The sealing gasket <NUM> can be made from any suitable elastomeric or other material as desired.

Referring again to <FIG>, it should be appreciated that the plunger <NUM>, the damper housing <NUM>, the rotor retainer cap <NUM>, and the damper housing cap <NUM> can all be attached to each other with respect to translation as to define a first assembly <NUM>. The first assembly <NUM> is translatable in each of the proximal direction and the distal direction with respect to the barrel <NUM> without rotating about the axis <NUM>. Thus, the plunger <NUM>, the damper housing <NUM>, the rotor retainer cap <NUM>, and the damper housing cap <NUM> can be rotatably fixed to each other. Further, the base <NUM> can be fixed to the damper housing <NUM> and the plunger <NUM> with respect to rotation.

In particular, referring now to <FIG> and <FIG>, the plunger <NUM> and the damper housing <NUM> are configured to interlock with each other so as to rotatably fix the plunger and damper housing <NUM> to each other. For instance, the plunger <NUM> and the damper housing <NUM> can define complementary engagement members that interlock with each other such that the plunger <NUM> and the damper housing <NUM> are rotatably fixed to each other. The plunger <NUM> defines a radially outer surface 31a and a radially inner surface 31b opposite the radially outer surface 31a. The plunger <NUM> can define at least one groove <NUM> that extends radially into the radially inner surface 31b and is elongate along the axial direction. The at least one groove <NUM> can include a plurality of grooves <NUM> that are circumferentially spaced from each other. The damper housing <NUM> can define at least one rib <NUM> that projects radially out from the radially outer surface 32a. The at least one rib <NUM> can include a plurality of ribs <NUM> that are circumferentially spaced from each other. The ribs <NUM> are complementary to the grooves <NUM>, and are configured to be inserted into the grooves <NUM>, respectively, so as to rotatably fix the plunger <NUM> to the damper housing <NUM> when the proximal end of the damper housing <NUM> is received in a distal end of the plunger <NUM>. Alternatively, the damper housing <NUM> can define the at least one groove, and the plunger <NUM> can define the at least one rib. Alternatively still, it should be appreciated that the engagement members of the plunger <NUM> and damper housing <NUM> can be constructed in accordance with any suitable alternative embodiment as desired, and can include geometric cross-sectional shapes of the plunger <NUM> and the damper housing <NUM>. Further, the distal end of the plunger <NUM> can alternatively be received in the proximal end of the damper housing <NUM>.

With continuing reference to <FIG> and <FIG>, the base <NUM> can couple to either or both of the damper housing <NUM> and the plunger <NUM> so as to rotatably fix the base <NUM>, the damper housing <NUM>, and the plunger <NUM> to each other. In particular, either or both of the plunger <NUM> and the damper housing <NUM> can define a respective first engagement member, and the base <NUM> includes a second engagement member that interlocks with the first engagement member to rotatably fix the base <NUM>, the damper housing <NUM>, and the plunger <NUM> to each other. In one example, the plunger <NUM> defines at least one first slot segment 94a that extends into its radially outer surface 31a, and is elongate along the axial direction. The at least one first slot segment 94a can include a plurality of first slot segments 94a circumferentially spaced from each other. The damper housing <NUM> defines a second slot segment 94b that extends into its radially outer surface 32a and is elongate along the axial direction. The at least one second slot segment 94b can include a plurality of second slot segments 94b circumferentially spaced from each other. When the plunger <NUM> is coupled to the damper housing <NUM> such that the respective engagement members interlock, the first and second slot segments 94a and 94b are aligned, such that the first and second slot segments <NUM> and <NUM> combine to define at least one slot <NUM>.

The first and second slot segments 94a and 94b, and thus the at least one slot <NUM>, define respective engagement members that are configured to interlock with a complementary engagement member of the base <NUM> so as to rotatably fix the base <NUM> to each of the plunger <NUM> and the damper housing <NUM>. In particular, the base <NUM> can include a projection <NUM> that projects radially inward from a radially inner surface 97a of the base <NUM> that is opposite a radially outer surface 97b of the base <NUM>. The radially inner surface 97a faces the damper housing <NUM> when the plunger <NUM> is in the initial position, and faces the damper housing <NUM> and the plunger <NUM> when the plunger is depressed. The projection <NUM> rides in the slot <NUM> as the plunger moves between the initial undepressed position and the fully depressed position. Because the damper housing <NUM> and the plunger <NUM> are rotatably fixed to each other, the base <NUM> is also rotatably fixed to the first assembly both when the plunger <NUM> is in the undepressed position, and when the plunger <NUM> is in the depressed position. While in one example the engagement member of the plunger <NUM> and the damper housing <NUM> defines a slot, and the complementary engagement member of the base <NUM> defines a rib, it is recognized that the engagement members can be alternatively configured as desired. For instance, the engagement member of the base <NUM> can define a slot, and the engagement member of the plunger <NUM> and the damper housing <NUM> can define a projection.

Referring again to <FIG>, the rotor <NUM>, the clutch <NUM>, and the rotor cap <NUM> are rotatably fixed to each other at least with respect to the first direction of rotation so as to define a second assembly <NUM>. The second assembly <NUM> is rotatable with respect to the first assembly <NUM> in the first direction of rotation. Further, the first and second assemblies <NUM> and <NUM> are configured to travel together with respect to the barrel <NUM> in each of the distal direction and the proximal direction.

The first assembly <NUM> defines a first or distal stop assembly that prevents translation of the first assembly <NUM> in the distal direction once the injection training device has been moved to its fully deployed position. The distal stop assembly is defined by first and second distal stop members <NUM> and <NUM> that abut each other when the plunger <NUM> has moved to a fully depressed position. In one example, the first distal stop member <NUM> can be defined by a first distal stop surface <NUM> of the barrel <NUM>. The first distal stop surface <NUM> can define a distal end of an internal annular gap <NUM> that extends in the distal direction into the barrel <NUM>. The second distal stop member <NUM> can be defined by the damper housing cap <NUM>. The second distal stop member <NUM> can define a second distal stop surface <NUM> that is configured to abut the first stop surface <NUM>. The second distal stop surface <NUM> can be defined by a distal surface of the second distal stop member <NUM>. As illustrated in <FIG>, as the plunger <NUM> reaches the fully depressed position, the second distal stop member <NUM> is received in the internal annular gap <NUM> until the first and second distal stop surfaces <NUM> and <NUM> abut each other, thereby preventing further movement of the plunger <NUM> in the distal direction with respect to the barrel <NUM>.

Referring again to <FIG>, the injection training device <NUM> further includes a second or proximal stop assembly that is configured to prevent movement of the plunger <NUM> in the proximal direction with respect to the barrel <NUM> when the plunger is <NUM> in the initial or undepressed position. The proximal stop assembly is defined by first and second proximal stop members <NUM> and <NUM> that abut each other when the plunger <NUM> is in the initial or undepressed position, thereby preventing the plunger from traveling in the proximal direction with respect to the barrel <NUM>. In one example, the first proximal stop member <NUM> can be defined by the damper housing <NUM>, and can project radially outward from the radially outer surface 32a of the damper housing <NUM>. The first proximal stop member <NUM> defines a first proximal stop surface <NUM>. The second proximal stop member <NUM> can be supported by the barrel <NUM>. In particular, the injection training device <NUM> can include a retention member <NUM> that can be attached to, and thus supported by, the barrel <NUM>. The retention member <NUM> can be disposed at a location in radial alignment with the barrel flange <NUM>, or any suitable alternative location. The retention member <NUM> can define a second proximal stop surface <NUM> that faces the first proximal stop surface <NUM>. When the plunger <NUM> is in the initial undepressed position, the first and second proximal stop surfaces <NUM> and <NUM> abut each other, thereby preventing movement of the plunger <NUM> in the proximal direction with respect to the barrel <NUM>. Thus, the proximal stop assembly can prevent the plunger <NUM> from inadvertently backing out entirely from the barrel <NUM>.

Operation of the injection training device <NUM> will now be described with reference to <FIG> generally. As shown at <FIG>, the device begins in the first or undeployed position, whereby the plunger <NUM> is in the undepressed position. To simulate an injection, the user applies a deployment force to the plunger <NUM> in the distal direction sufficient to urge the first assembly <NUM> to translate in the distal direction with respect to the barrel <NUM>. In one example, the first assembly <NUM> can be rotatably fixed, such that the plunger <NUM> and the damper housing <NUM> do not undergo rotation as they translate in the distal direction. Thus, movement of the first assembly <NUM> in the first direction can be pure translation. Translation of the first assembly <NUM>, and in particular of the plunger <NUM>, in the distal direction causes a force to be applied to the rotor <NUM> that causes the rotor <NUM> to travel in the distal direction as the rotor rotates within the damper housing <NUM> in the first direction of rotation about the axis of rotation <NUM>. In particular, the rotor <NUM> applies the force in the distal direction to the clutch <NUM>, thereby driving the clutch <NUM> to travel in the distal direction. As the clutch <NUM> travels in the distal direction, the threaded shaft <NUM> causes the clutch <NUM> to rotate in the first direction of rotation. As the clutch <NUM> rotates in the first direction of rotation, the teeth <NUM> and <NUM> (see <FIG>) engage such that the rotor <NUM> rotates with the clutch <NUM>.

As described above, and referring also to <FIG>, the rotor rotates with respect to the damper housing <NUM> in the first direction of rotation about the axis <NUM>. The rotor <NUM> and the damper housing <NUM> define the damper chamber <NUM> that extends radially from the radially outer surface <NUM> of the rotor <NUM> to the radially inner surface 32b of the damper housing <NUM>. The viscous fluid <NUM> disposed in the damper chamber <NUM> provides a rotational counterforce that resists rotation of the rotor <NUM>, thereby also resisting the rotation of the clutch <NUM> in the distal direction, which thereby also provides a resistive force that resists movement of the plunger <NUM> in the distal direction. Accordingly, the user experiences a resistance when depressing the plunger <NUM> that simulates the resistance that will be experienced by the user when depressing the plunger <NUM> of the corresponding injection device to deliver medication. The user continues to depress the plunger against the resistance provided by the viscous fluid <NUM> until the plunger <NUM> has reached the fully depressed position illustrated in <FIG>, whereby the first and second distal stop members abut each other, thereby preventing further movement of the plunger <NUM> in the distal direction. The resistance against the movement of the plunger <NUM> in the distal direction results in a time duration to move the plunger <NUM> from the initial undepressed position to the final fully depressed position. The time duration can simulate the time duration to fully deliver the medication from the corresponding injection device.

It should be appreciated that the injection training device <NUM> can be tuned to vary the resistance to movement of the plunger <NUM> in the distal direction, and also the resulting time duration to move the plunger <NUM> from the first undepressed position to the final fully depressed position. For instance, the viscosity of the viscous fluid <NUM> disposed in the damper chamber <NUM> can be adjusted to vary the counterforce to rotation of the rotor <NUM> with respect to the damper housing <NUM>, and consequently the resistive force that resists depression of the plunger <NUM>. A higher viscosity fluid will increase the resistance to rotation of the rotor <NUM> with respect to the damper housing <NUM>, while a lower viscosity fluid will decrease the resistance to the rotation of the rotor <NUM> with respect to the damper housing <NUM>. In one example, the viscous fluid can be DG4810 damping grease commercially available from Dongguan Vnovo Lubricants Technology Co. having a place of business in Guangdong, China. The viscous fluid can have a viscosity of approximately <NUM>,<NUM> CST at <NUM> degrees C, though it is recognized that the injection training device <NUM> can be tuned to work with virtually any viscosity that resists rotation of the rotor <NUM> relative to the damper housing <NUM>. Further, the size of the knurls <NUM>, and thus the radial distance from the rotor <NUM> to the damper housing <NUM> can also impact the counterforce to rotation of the rotor <NUM>. In general, greater radial distances from the rotor <NUM> to the damper housing <NUM> will decrease the counterforce to rotation of the rotor <NUM>. In general, decreased radial distances from the rotor <NUM> to the damper housing <NUM> will increase the counterforce to rotation of the rotor <NUM>. In one example, a proximal portion of the rotor <NUM> can have a different outer diameter than a distal portion of the rotor <NUM>. For instance, the outer diameter of the proximal portion of the rotor <NUM> can be less than the outer diameter of the distal portion of the rotor <NUM>. At the proximal portion of the rotor <NUM>, a first proximal radial distance from the radially outermost surface of the knurls to the damper housing <NUM> can range from approximately <NUM> to approximately <NUM>, such as approximately <NUM>. At the proximal portion of the rotor <NUM>, a second proximal radial distance from the radially outer surface of the rotor <NUM> between adjacent ones of the knurls to the damper housing <NUM> is greater than the first proximal radial distance. The second proximal radial distance can range from approximately <NUM> to approximately <NUM>, such as approximately <NUM>. At the distal portion of the rotor <NUM>, a first distal radial distance from the radially outermost surface of the knurls to the damper housing <NUM> can range from approximately <NUM> to approximately <NUM>, such as approximately <NUM>. At the distal portion of the rotor <NUM>, a second distal radial distance from the radially outer surface of the rotor <NUM> between adjacent ones of the knurls to the damper housing <NUM> is greater than the first distal radial distance. For instance, the second distal radial distance can range from approximately <NUM> to approximately <NUM>, such as approximately <NUM>. Alternatively, the outer diameter of the proximal portion of the rotor <NUM> can be greater than the outer diameter of the distal portion of the rotor <NUM>. It is recognized that these distances can vary greatly depending on the viscosity of the viscous fluid. The term "approximately" as used herein with reference to a size, shape, distance, or other parameter can include the stated parameter as well as up to <NUM>% greater than the stated parameter and up to <NUM>% less than the stated parameter. Further still, one or both of the radially outer surface of the rotor <NUM> and the radially inner surface 32b of the damper housing <NUM> can be textured. Greater textured surface area will generally increase the counterforce to rotation of the rotor. Reductions in textured surface area will generally decrease the counterforce to rotation of the rotor <NUM>.

The injection training device <NUM> is designed for the plunger <NUM> to be returnable to the initial undepressed position after it has travelled to a position distal of the undepressed position. In particular, once the plunger <NUM> has traveled to a position distal of the undepressed position, for instance the final fully depressed position, the user can apply a return force to the plunger <NUM>. The return force is directed in the proximal direction, and urges the plunger <NUM> to move in the proximal direction with respect to the barrel <NUM> toward the initial undepressed position. The return force applied to the plunger <NUM> is also applied to the damper housing <NUM>, which is coupled to the plunger <NUM> with respect to movement in the proximal direction, and to the damper housing cap <NUM> which is coupled to the damper housing <NUM> with respect to movement in the proximal direction. Movement of the damper housing cap <NUM> in the proximal direction causes the biasing member <NUM> to urge the clutch <NUM> to move in the proximal direction. As the clutch <NUM> is in contact with the rotor <NUM>, movement of the clutch <NUM> in the proximal direction causes the rotor <NUM> to move in the proximal direction. Alternatively or additionally, the rotor cap <NUM> can be translationally fixed to the plunger <NUM>. Thus, the rotor cap <NUM>, which is attached to the rotor <NUM>, can rotate with respect to the plunger <NUM>, but translates with the plunger <NUM>. Either way, translation of the plunger <NUM> in the proximal direction causes the clutch <NUM> and the rotor <NUM> to travel in the proximal direction.

As described above, because the clutch <NUM> is threadedly mated with the shaft <NUM>, the threaded shaft <NUM> drives the clutch to rotate in the second direction of rotation as the clutch <NUM> moves in the proximal direction. However, because the teeth <NUM> of the clutch <NUM> and the teeth <NUM> of the rotor <NUM> are not coupled with respect to the second direction rotation, the teeth <NUM> slip over the teeth of the rotor <NUM> as the clutch <NUM> rotates in the second direction of rotation. Therefore, the clutch <NUM> does not drive the rotor <NUM> to rotate in the second direction of rotation. The rotor <NUM> consequently translates with the plunger <NUM> in the proximal direction without undergoing rotation in the second direction of rotation. It is envisioned that contact between the teeth <NUM> of the clutch <NUM> and the teeth <NUM> of the rotor <NUM> may cause the rotor <NUM> to undergo minor rotation, depending on the resistance provided by the viscous fluid <NUM>, but such rotation should it occur is inconsequential. It can thus be said that the rotor is rotationally fixed as it translates in the proximal direction. Thus, the viscous fluid <NUM> does not provide a counterforce against travel of the plunger in the proximal direction.

In alternative embodiments, it is recognized that the teeth <NUM> and <NUM> can be rotatably fixed in the second direction of rotation, such that the rotor <NUM> rotates in the second direction of rotation with the clutch <NUM>. Alternatively, the clutch <NUM> and the rotor <NUM> can be a single unitary component. In this embodiment, the viscous fluid <NUM> provides a rotational counterforce against rotation of the rotor <NUM> in the second direction of rotation with respect to the damper housing <NUM>. The rotational counterforce creates a resistive force against movement of the plunger <NUM> in the proximal direction.

Claim 1:
An injection training device (<NUM>) comprising:
a barrel (<NUM>);
a first assembly (<NUM>) including a plunger (<NUM>) and a damper housing (<NUM>) coupled to the plunger (<NUM>), wherein the first assembly (<NUM>) is translatable with respect to the barrel (<NUM>); and
a second assembly (<NUM>) including a rotor (<NUM>), such that a damper chamber (<NUM>) is defined between the rotor (<NUM>) and the damper housing (<NUM>), wherein a viscous fluid (<NUM>) is disposed in the damper chamber (<NUM>),
wherein translation of the first assembly (<NUM>) causes a force to be applied to the rotor (<NUM>) that causes the rotor (<NUM>) to rotate about an axis of rotation with respect to the damper housing (<NUM>), and the viscous fluid (<NUM>) resists rotation of the rotor (<NUM>) about the axis with respect to the damper housing (<NUM>).