Injection devices and components thereof

Abstract

An injection device and method of using the same are disclosed. The injection device includes an injection drive assembly including a pneumatic piston chamber, a dose chamber, a pneumatic piston slidably disposed in the pneumatic piston chamber, and an injectate piston slidably disposed in the dose chamber. The injection drive assembly is configured such that any energy resulting from the application of force to the injection drive assembly is immediately available to begin an injection cycle. In another aspect, the injection device includes a separate respective spring member for each of the pistons configured to place each piston in its respective pre-injection position. In another aspect, the injection device includes a valve assembly configured to provide pressurized fluid to the pneumatic piston chamber. The speed at which the valve moves between an open position and a closed position is independent of control by a user of the injection device.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of injection devices. BACKGROUND

[0002] Injection of humans and animals is typically performed by syringes with needles. Needle-free injection is an emerging delivery method as there are many disadvantages to using needles, including pain, waste of medical sharps, and risk of disease transmission through repeated use of needles.

[0003] Needle-free injection devices typically use a pneumatic piston (referred to as a power piston) slidably disposed in a pneumatic piston chamber to drive an injectate piston (referred to as a plunger or hydraulic piston) slidably disposed in a dose chamber forward to expel a liquid under pressure through an orifice. The pneumatic piston slidably disposed in the pneumatic piston chamber and the injectate piston slidably disposed in the dose chamber are components of the injection drive assembly of the injection device. This process of pressurizing the liquid and expelling the liquid through the orifice creates a very narrow jet of injection that is capable of piercing the tissue of a human or animal. Springs, magnets, locks, hydraulic devices, and pneumatic devices are typically used to push the power piston, which in turn pushes the plunger or other drug piston. In needle-free injectors, the power piston propulsion system is important as it is desirable to create a very high initial pressure on the liquid to be expelled. This very high initial pressure on the liquid helps the initial portion of the jet of injection to penetrate the tissue and create an opening through which the remaining portion of the jet of injection can pass and enter the tissue. If the initial hydraulic pressure is insufficient, the initial portion of the jet of injection can not penetrate the target tissue and prevent the full dose of the injection liquid from being expelled, or the jet of injection can not reach the desired injection depth, such as the subcutaneous or muscle tissue layers.

[0004] Because the initial hydraulic pressure is determined by the rate of movement of the power piston and the drug piston, injection devices often include an accumulator. The term "accumulator" as used herein refers to a device or component of the injection drive assembly configured to store potential energy (e.g., in the form of a stored pressurized fluid) until the stored potential energy reaches a predetermined threshold before any of the energy is available to initiate an injection cycle. The term "injection cycle" as used herein refers to the movement of the injection drive assembly from a pre-injection position to a post-injection position and back to the pre-injection position. Accumulators enable the power piston to accelerate rapidly at the start of an injection cycle. For example, a spring can be attached to the power piston, and the spring can be compressed and held so that once the spring is released, the power piston travels rapidly forward with an initial burst of energy. One limitation of accumulators is that they require additional components to store potential energy and to hold or lock the power piston in the pre-injection position until the stored energy is released. Furthermore, the operation of accumulators results in additional wear of the power piston and any components that hold or lock the power piston in the pre-injection position until the stored energy is released. In the spring example described above, the spring and the power piston wear during the time that the spring is compressed but has not yet been released. Furthermore, the clamp or other holding mechanism that holds the spring in the compressed position and / or holds or locks the power piston until the stored energy is released can wear over time. Similar limitations exist in other accumulators, including magnets, locks, hydraulic devices, and pneumatic devices.

[0005] In the art, it is also common for the power piston to be attached to the drug piston so that movement of one of the pistons also moves the other piston. This attachment of the power piston to the drug piston allows both pistons to move forward in unison at the start or initiation of an injection cycle. Similarly, when preparing a syringe for an injection, because the power piston and the hydraulic piston are attached to each other, only one of the pistons needs to be forced to achieve movement of both pistons. However, the attachment of the power piston to the drug piston does have disadvantages. For example, forward or distal movement of the power piston is impeded by the attachment of the power piston to the drug piston because the drug piston creates additional resistance. In many applications, this impediment to movement of the power piston does not hinder the power piston and the drug piston from creating a pulse sufficient to perform an injection. However, in some high work load and / or high stress applications (e.g., injecting large animals), anything that impedes forward movement of the power piston can require more energy to perform an injection or negatively impact the quality of the injection.

[0006] An example of an injection device comprising an accumulator and a power piston attached to a drug piston is shown and described in U.S. Patent No. 6,770,054. The '054 patent is incorporated herein by reference in its entirety. The injection device disclosed in the '054 patent includes a ball-lock assembly that is locked and then released (unlocked) to drive the power piston distally, which in turn drives a drug / hydraulic piston attached to the power piston distally. This distal movement of the drug piston expels the drug from the device. The ball-lock assembly is capable of releasing from its locked position to drive the power piston forward when a predetermined amount of pneumatic pressure is reached in the pneumatic piston chamber or cylinder. Thus, at least the ball-lock assembly functions as an accumulator, and more specifically, as a pressurized fluid accumulator. The power piston is held in the pre-injection position by the ball-lock assembly until the predetermined amount of pneumatic pressure is reached in the pneumatic piston chamber. Also as described in the '054 patent, the power piston and the drug piston are a single, integrated component, so movement of the power piston necessarily drives the drug piston.

[0007] Another example of an injection device including an accumulator and a power piston attached to a drug piston is shown and described in U.S. Patent No. 5,782,802 (“802 Patent”). The injection device disclosed in the 802 Patent includes a ball-lock assembly that is locked and then released (unlocked) to drive the power piston distally, which in turn drives the drug piston attached to the power piston distally. This distal movement of the drug piston displaces the drug from the device. The ball-lock assembly can be released from the locked position when a mechanical spring is engaged and in the locked position to drive the power piston forward. Thus, at least the ball-lock assembly functions as an accumulator. The power piston is held in the pre-injection position until the operator presses the injection button to release the power piston. Furthermore, a piston head (drug piston) is securely mounted to a plunger head, which is an integral part of the plunger (power piston). Therefore, distal and proximal movement of the plunger (power piston) further causes distal and proximal movement of the piston head (drug piston).

[0008] Another example of an injection device comprising an accumulator and a power piston attached to a drug piston is shown and described in U.S. Patent No. 7,357,781 ("the '781 patent"). The injection device disclosed in the '781 patent comprises a magnetic lock assembly that is locked and then released (unlocked) to drive the piston (power piston) in a distal direction, which in turn drives the plunger (drug piston) attached to the power piston through a coupler to move distally. This distal movement of the plunger (drug piston) expels the drug from the device. The magnetic lock assembly is capable of being released from the locked position to drive the piston (power piston) forward when a predetermined amount of pneumatic pressure is reached. A trigger can be manually depressed to open an on / off gas valve. Once the on / off gas valve is opened, pressurized gas flows into a pressure chamber located behind the power piston. When the gas pressure in the pressure chamber overcomes the force of the magnetic lock, it pushes the piston (power piston) and plunger (drug piston) forward to expel the liquid through an orifice. Thus, at least the pressure chamber and the magnetic lock assembly function as a pressurized fluid accumulator. The power piston is held in a pre-injection position by the magnetic lock assembly until a predetermined amount of pneumatic pressure is reached within the pressure chamber. In addition, the plunger (drug piston) is securely mounted to a coupler that is slidably attached to the piston (power piston) by a puller (part of the power piston assembly). Thus, the drug piston and the power piston are indirectly attached to each other, and as a result, distal and proximal movement of the piston (power piston) in turn moves the plunger (drug piston) distally and proximally.

[0009] Another example of an injection device comprising an accumulator and a power piston attached to a drug piston is shown and described in U.S. Patent No. 6,676,630 ("the '630 patent"). The injection device disclosed in the '630 patent comprises a gas reservoir (pressure accumulator) that is separated from a piston chamber by a poppet valve. The poppet valve is capable of being released (unlocked) to supply high pressure gas from the gas reservoir to the piston chamber containing the piston (power piston) and the plunger (drug piston). The gas supplied from the gas reservoir to the piston chamber drives the piston (power piston) in a distal direction, which in turn drives the plunger (drug piston) in abutting contact with the power piston to move distally. This distal movement of the plunger (drug piston) expels the drug from the device. The poppet valve is capable of being released from a closed or locked position to supply high pressure gas to the piston chamber to drive the piston (power piston) forward when a predetermined amount of pneumatic pressure is reached in the gas reservoir. Thus, at least the gas reservoir functions as an accumulator. Once a predetermined amount of pressure is reached in the gas reservoir, the power piston is provided with a burst of power / pressure. In addition, the plunger (drug piston) is attached to the piston (power piston) and held by a spring (return spring). Thus, distal movement of the piston (power piston) in turn moves the plunger distally, and proximal movement of the plunger (drug piston) in turn moves the piston (power piston) proximally.

[0010] While the above injection devices function as intended, these designs suffer from certain deficiencies, including but not limited to the following. First, all of the above-mentioned injectors include a component that functions as an accumulator. While the use of an accumulator in an injection device enables the power piston to move quickly to achieve a high quality injection profile, accumulators tend to be a point of failure for many injectors. This is because accumulators store potential energy, subjecting them to a great deal of stress and wear. This increases the frequency of service, as the component that functions as an accumulator must be serviced or replaced. For example, magnets, springs, locks, and valves that function as accumulators can wear over time and subsequently fail to function as intended.

[0011] Second, the above injection devices are prone to providing inconsistent injections, as the operation of the valve that provides pressurized gas to the injection drive assembly can be affected by human error and / or fatigue. For example, for those injection devices that require an operator to press a button to open the valve to provide pressurized fluid to the injection drive assembly, the force with which the operator presses the button can affect the speed at which the valve moves from the closed position to the open position and / or whether the valve is only partially opened; which in turn can affect the rate of gas supply. For example, if the valve is only partially opened, the rate of gas supply can not be sufficient to achieve the predetermined pressure threshold within the accumulator of the injection device. This can result in the liquid in the dose chamber being expelled at a pressure and speed that is not sufficient to reach the target tissue depth. Alternatively, the pressure can not be sufficient to unlock the pneumatic piston, such that the liquid is not expelled from the dose chamber at all.

[0012] Third, because the injection devices as described above include a power piston that is attached to and / or in constant contact with the drug piston, more energy is required to move the pistons from the pre-injection position to the post-injection position. This limits the pressure profile of the injection in the injection cycle, as the power piston and the drug piston must be moved throughout the injection cycle, rather than only one component (the power piston) being moved in the initial phase of the injection cycle. SUMMARY

[0013] The present invention relates to an injection device and methods of using the same. The injection device includes an injection drive assembly, which itself includes a pneumatic piston chamber, a dose chamber, a pneumatic piston slidably disposed in the pneumatic piston chamber, and an injectate piston slidably disposed in the dose chamber.

[0014] In one aspect, an injection device of the present application can include an injection drive assembly. The injection drive assembly includes a pneumatic piston chamber, a dose chamber, a pneumatic piston slidably disposed in the pneumatic piston chamber, and an injectate piston slidably disposed in the dose chamber. The injection drive assembly is movable between a pre-injection position and a post-injection position. In certain aspects, the pneumatic piston and the injectate piston move independently of one another and are spaced apart from one another at certain positions within the injection device. The injection drive assembly is configured such that any energy resulting from the application of force to the injection drive assembly is immediately used to begin an injection cycle.

[0015] In another aspect, an injection device of the present application can include a separate respective spring member for each of the pneumatic piston and the injectate piston. Both the pneumatic piston and the injectate piston are movable between a pre-injection position and a post-injection position. Each respective spring member is configured to place each of the pneumatic piston and the injectate piston in the pre-injection position.

[0016] In another aspect, an injection device of the present application can include a valve assembly including a valve. The valve is movable between a closed position and an open position. The valve is configured to provide pressurized fluid to the pneumatic piston chamber when the valve is in the open position. The speed at which the valve moves between the closed position and the open position is independent of control by a user of the injection device.

[0017] In certain embodiments of each of the aspects of the injection device of the present application, the injection drive assembly is configured such that energy resulting from the application of force to the injection drive assembly is immediately used to begin an injection cycle without a) first storing the energy as potential energy until the stored potential energy reaches a predetermined threshold; and / or b) manually releasing the stored potential energy.

[0018] Preferably, the injection drive assembly does not include an accumulator, including but not limited to a pressure accumulator, such as a pressurized fluid accumulator. Thus, preferably, the pneumatic piston and the pneumatic piston chamber are not configured to operate as a pressure accumulator.

[0019] Preferably, the injection drive assembly does not include a lock configured to hold the injection drive assembly in the pre-injection position. Preferably, the pneumatic piston is not held in the pre-injection position with a lock.

[0020] In other embodiments of each of the aspects of the injection device of the present application, the injection device includes a separate respective spring member for each of the pneumatic piston and the injectate piston, the spring member configured to place each of the pneumatic piston and the injectate piston in the pre-injection position.

[0021] Preferably, the pneumatic piston and the injectate piston are not directly or indirectly attached to one another.

[0022] Preferably, the pneumatic piston and the injectate piston are spaced apart from one another when the injection drive assembly is in the pre-injection position.

[0023] Preferably, the injection drive assembly is configured such that energy resulting from the application of force to the injection drive assembly is immediately available to move the pneumatic piston through the space between the pneumatic piston and the injectate piston. More preferably, the injection drive assembly is configured such that the force applied to the injection drive assembly and the movement of the pneumatic piston creates kinetic energy sufficient to push the injectate piston forward.

[0024] Preferably, the pneumatic piston and the injectate piston are each in their proximal-most position when the injection drive assembly is in the pre-injection position. Preferably, the pneumatic piston and the injectate piston are each in their distal-most position when the injection drive assembly is in the post-injection position.

[0025] Preferably, each resilient member is a spring. Preferably, the force is provided by a pressurized fluid. More preferably, the pressurized fluid is a pressurized gas, a pressurized fluid, and combinations thereof.

[0026] In other embodiments of the injection device of the present application, the injection device includes a valve assembly. The valve assembly includes a valve that is movable between a closed position and an open position and is configured to provide pressurized fluid to the injection drive assembly when the valve is in the open position. The speed of the valve between the closed position and the open position is independent of control by a user of the injection device.

[0027] Preferably, the valve assembly further includes a valve switch resilient member and a valve switch. The valve switch resilient member is operable to move the valve switch from a valve closed position to a valve open position. Preferably, the valve switch resilient member is a spring. More preferably, the valve assembly further includes a valve switch latch configured to releasably retain the valve switch in the valve closed position.

[0028] Preferably, the injection device further includes a pneumatic piston chamber resilient member movable between a pre-actuation position and an actuation position. The pneumatic piston chamber resilient member is configured to place the pneumatic piston chamber in the pre-actuation position. Preferably, the valve switch resilient member is configured to be actuated by movement of the pneumatic piston chamber to the actuation position. Preferably, the pneumatic piston chamber resilient member is a spring.

[0029] In another aspect, the present invention relates to a method of using an injection device employing various aspects of the invention. The method includes the step of applying a force to an injection drive assembly. The energy resulting from applying the force to the injection drive assembly can be immediately used to initiate an injection cycle. Preferably, the energy resulting from applying the force to the injection drive assembly can be immediately used for the injection cycle without a) first storing the energy as potential energy until the stored potential energy reaches a predetermined threshold; and / or b) manually releasing the stored potential energy.

[0030] Preferably, the method further includes the additional step of applying a first force to the injection drive assembly in the pre-injection position. This first force is sufficient to exceed a second force applied by a corresponding elastic member of the pneumatic piston. The first force forces the pneumatic piston to move distally. This distal movement of the pneumatic piston causes it to contact the injectable piston, thereby applying a third force to the injectable piston. This third force is sufficient to exceed a fourth force applied by a corresponding elastic member of the injectable piston. This third force forces the injectable piston to move distally. The injection drive assembly is moved to the post-injection position, thereby forcing the injectable material stored in the dosing chamber to leave the dosing chamber. The third force is generated by the first force and the kinetic energy produced by the movement of the pneumatic piston. This kinetic energy depends on the length of the space between the pneumatic piston and the injectable piston. Preferably, the first force is provided by a pressurized fluid. More preferably, the pressurized fluid is a pressurized gas, a pressurized liquid, or a combination thereof.

[0031] Preferably, the method further includes the additional steps of supplying pressurized fluid to the valve and moving the valve to an open position. The speed at which the valve moves between the closed and open positions is independent of user control of the injection device. More preferably, the method further includes the additional steps of supplying pressurized fluid to the valve and moving the pneumatic piston chamber from a pre-actuation position to an actuated position. The movement of the pneumatic piston chamber to the actuated position causes actuation of the valve switch resilient member. Upon actuation, the valve switch resilient member causes the valve switch to move the valve from the closed position to the open position. Once the valve is in the open position, the valve supplies pressurized fluid to the pneumatic piston chamber. Preferably, the pressurized fluid is a pressurized gas, a pressurized liquid, or a combination thereof. Attached Figure Description

[0032] Figure 1 This is a cross-sectional view of an exemplary injection device of the present invention, wherein the components of the injection drive assembly are in the pre-injection position and the components of the valve are in the closed position.

[0033] Figure 2 yes Figure 1 A cross-sectional view of the injection device, wherein the components of the injection drive assembly are in the post-injection position and the valve is in the open position.

[0034] Figure 3 yes Figure 1A cross-sectional view of the injection device, wherein the actuation return spring and valve spring are fully compressed or lifted, the injection drive assembly is in the pre-injection position, and the valve is in the closed position.

[0035] Figure 4 yes Figure 1 A cross-sectional view of the injection device, wherein the actuation return spring is fully compressed or lifted, the injection drive assembly is in the pre-injection position, and the valve is in the open position.

[0036] Figure 5 yes Figure 1 A perspective view of the holder of the injection device. Detailed Implementation

[0037] This invention relates to an injection device and its method of use. The injection device includes a pneumatic piston chamber, a dosage chamber, a pneumatic piston slidably disposed in the pneumatic piston chamber, and an injection piston slidably disposed in the dosage chamber. The injection device of this invention can be used for injection into animals and humans.

[0038] In one aspect, the injection device of the present invention may include an injection drive assembly. The injection drive assembly includes a pneumatic piston chamber, a dosing chamber, a pneumatic piston slidably disposed in the pneumatic piston chamber, and an injectable piston slidably disposed in the dosing chamber. The injection drive assembly is movable between a pre-injection position and a post-injection position. In some aspects, the pneumatic piston and the injectable piston move independently of each other and are spaced apart from each other at certain positions within the injection device. The injection drive assembly is configured such that any energy resulting from applying a force to the injection drive assembly can be immediately used to initiate an injection cycle.

[0039] In another aspect, the injection device of the present invention may include separate respective resilient members for each of the pneumatic piston and the injection piston. Both the pneumatic piston and the injection piston are movable between a pre-injection position and a post-injection position. Each respective resilient member is configured to position each of the pneumatic piston and the injection piston in the pre-injection position.

[0040] In another aspect, the injection device of the present invention may include a valve assembly comprising a valve. The valve is movable between a closed position and an open position. The valve is configured to supply pressurized fluid to a pneumatic piston chamber when it is in the open position. The speed at which the valve moves between the closed and open positions is independent of user control of the injection device.

[0041] The above aspects of the injection device of the present invention are referred to herein. Figure 1The exemplary embodiment of the injection device 10 shown is illustrated. Although the injection device 10 includes all the above-described aspects of the injection device of the present invention, it should be understood that the injection device of the present invention may include only some of these aspects (not all of them). Furthermore, although some components of the injection device 10 have been described with reference to the drawings, it should be understood that modifications may be made to the configuration and relationships of certain components, etc.

[0042] Please refer to Figure 1 The injection device 10 is a needleless injection device. However, injection devices including needles are also within the scope of this invention. The injection device 10 includes an injection drive assembly 12, a cylindrical housing 14, a valve assembly 16, and an actuation return spring 18. The injection drive assembly 12 includes a pneumatic piston 20, a pneumatic piston return spring 22, a pneumatic piston chamber 24, an injection piston 26, an injection piston return spring 28, a dosage chamber 30, and a dosage chamber mounting bracket 32. Components of the injection device 10 and the injection drive assembly 12 can be... Figure 1 The pre-injection position shown is the same as Figure 2 The injection drive assembly 12 is generally cylindrical and axially aligned with each other and with the actuated return spring 18 and housing 14. A dose chamber mount 32 is attached to the distal end of the pneumatic piston chamber 24, and a cylindrical dose chamber mounting flange 34 of the dose chamber 30 is removably attached to the distal end of the dose chamber mount 32 using a dose chamber nut 36. The pneumatic piston 20 is slidably positioned within a pneumatic piston chamber cavity 38 defined by the pneumatic piston chamber 24 and the dose chamber mount 32. The distal portion of the injector piston 26 is slidably positioned within a dose chamber cavity 40 defined by the dose chamber 30, and the proximal portion of the injector piston 26 and the spring plate 42 attached thereto are positioned within the pneumatic piston chamber cavity 38. The pneumatic piston chamber 24 is slidably positioned within a housing cavity 44 defined by the housing 14. The actuation return spring 18 is also placed in the inner cavity 44 of the housing between the proximal end of the pneumatic piston chamber 24 and the proximal end wall 46 of the housing 14.

[0043] Please refer to Figure 1 Both the pneumatic piston return spring 22 and the injection piston return spring 28 are elastic members configured to position each corresponding pneumatic piston and injection piston in the pre-injection position. As described herein, the pneumatic piston return spring 22 and the injection piston return spring 28 are respectively configured to position the corresponding pneumatic piston 20 and injection piston 26 from... Figure 2 The injection site shown returned to Figure 1The pre-injection position is shown. The pneumatic piston 20 and the injectate piston 26 are separate components that are not directly or indirectly attached to one another and are capable of moving independently of one another. Further, while the pneumatic piston 20 and the injectate piston 26 can be in abutting contact with one another (e.g., in the post-injection position), they are not in abutting contact with one another in all positions (e.g., in the pre-injection position).

[0044] Returning to Figure 1 , the pneumatic piston 20 and the injectate piston 26 are each in their proximal-most positions and are spaced apart from one another. As described herein, the spacing between the pneumatic piston 20 and the injectate piston 26 in the pre-injection position is important and affects the overall performance of the injection device 10. This spacing allows the pneumatic piston 20 to move independently and, thus, to accumulate kinetic energy before engaging the proximal end of the injectate piston 26 shortly after the start of the injection cycle. Thus, the distance between the pneumatic piston 20 and the injectate piston 26 in the pre-injection position determines how much kinetic energy the pneumatic piston 20 will accumulate before engaging the injectate piston 26. Accordingly, the spacing between the pneumatic piston 20 and the injectate piston 26 is directly related to the ability of the liquid expelled by the injection device 10 to penetrate the skin of an animal or a human. Thus, by increasing the spacing between the pneumatic piston 20 and the injectate piston 26, the liquid expelled by the injection device 10 is able to penetrate thicker tissue. Conversely, by decreasing the spacing between the pneumatic piston 20 and the injectate piston 26, the injection device 10 can be optimized to inject into thinner tissue.

[0045] Still referring to Figure 1 , the proximal end of the pneumatic piston return spring 22 is in abutting contact with the pneumatic piston 20 and the distal end of the pneumatic piston return spring 22 is in abutting contact with the dose chamber mount 32. The pneumatic piston return spring 22 exerts a force sufficient to place the pneumatic piston 20 in the pre-injection position. The proximal end of the pneumatic piston 20 is in a position to abut against the proximal end of the pneumatic piston chamber 24. The proximal end of the injectate piston return spring 28 is in abutting contact with the distal end of the spring plate 42 and the distal end of the injectate piston return spring 28 is in abutting contact with the dose chamber mounting flange 34. The injectate piston return spring 28 exerts a force sufficient to place the injectate piston 26 in the pre-injection position. The proximal end of the actuation return spring 18 is in abutting contact with the proximal end wall 46 of the housing 14 and the distal end of the actuation return spring 18 is in abutting contact with the proximal end of the pneumatic piston chamber 24. The actuation return spring exerts a force sufficient to place the pneumatic piston chamber 24 in the position shown. The pneumatic piston return spring 22, the injectate piston return spring 28, and the actuation return spring 18 each operate independently to place the respective pneumatic piston 20, injectate piston 26, and pneumatic piston chamber 24 in Figure 1 the positions shown. While the actuation return spring 18, the pneumatic piston return spring 22, and the injectate piston return spring 28 are all springs, any suitable resilient member configured to place these components in the pre-injection position is within the scope of the present disclosure.

[0046] Prior to the start of an injection, the resilient members (e.g. Figures 1-3 springs) provide sufficient force to place their respective components in the desired position. However, they differ from the locks of the prior art in that the force required to move and hold the respective components in place is minimal because there is no cumulative potential energy that the resilient members need to overcome. This is important because, as discussed in more detail below, the force provided by the resilient members is easily overcome by forces applied in the opposite direction during the injection cycle. Furthermore, unlike the accumulators of the prior art, the force exerted by the resilient members on the injection drive assembly at the start of the injection cycle is opposite the direction of movement of the injection drive assembly. As a result, any potential energy in the resilient members is generated during the injection cycle, not before, and is released at the end of the injection cycle. There is no such potential energy to start the injection cycle before it begins.

[0047] Movement of the injection drive assembly 12 between the pre-injection position shown in Figure 1 and the post-injection position shown in Figure 2 is achieved by applying a force to the injection drive assembly 12. As shown, the injection device 10 is configured such that this force is provided by pressurized gas (not shown) that is supplied to the injection drive assembly 12 via the valve assembly 16 when the valve 48 is in the open position. Other suitable pressurized fluids include pressurized liquids or a combination of one or more pressurized gases and one or more pressurized fluids. Alternatively, the force provided to the injection drive assembly 12 can be provided by any suitable mechanism configured to push the injection drive assembly between the pre-injection position and the post-injection position.

[0048] As described herein, the injection drive assembly 12 is configured such that any energy resulting from the application of force to the injection drive assembly 12 is immediately available to begin an injection cycle. As described above, part of the reason this occurs is that the force exerted by the resilient member is minimal, and part of the reason is that the power piston 20 is spaced apart from the injectate piston 26 in the pre-injection position. In addition, the injection drive assembly 12 does not include one or more components that store energy as potential energy prior to the start of an injection cycle until the stored potential energy reaches a predetermined threshold or is manually released prior to making the energy available to begin an injection cycle. Thus, the injection drive assembly 12 does not include an accumulator or a pressure accumulator, none of the components thereof (including the power piston 20, the power piston chamber 24, the power piston return spring 22, the injectate piston return spring 28, the injectate piston 26, and the injectate piston return spring 28) function as an accumulator or a pressure accumulator, and the injection drive assembly 12 does not include a lock configured to resist potential energy to hold the injection drive assembly 12 or any of its components in the pre-injection position. For example, the injection drive assembly 12 does not include a lock (such as a ball lock assembly (e.g., as disclosed in the '054 patent), a magnet, or a valve under pressure exerted by potential energy prior to the start of an injection cycle. The injection drive assembly 12 also does not include a spring under pressure exerted by potential energy prior to the start of an injection cycle. As a result, the injection drive assembly 12 and the injection device 10 are not susceptible to wear and tear and are not susceptible to part failure.

[0049] Referring again to Figure 2 One aspect of the present application relates to the valve assembly 16 shown in the figure. The valve assembly 16 includes a cylindrical spool valve 48, a cylindrical spool valve switch 50, a spool valve switch spring 52, and a plurality of spool valve switch latches 54. Although only two spool valve switch latches 54 are shown, the valve assembly 16 includes four valve switch latches 54. Although the valve assembly 16 includes four valve switch latches 54, it is within the scope of the present application for the valve assembly 16 to have more than four and as few as one valve switch latch 54. The components of the valve assembly 16 are movable between Figure 1 the position shown (closed position of the valve 48) and Figure 2 and Figure 4 the position shown (open position of the valve 48). As described herein, the speed of movement of the valve 48 between the closed position and the open position is independent of the control of a user of the injection device 10.

[0050] Referring again to Figure 2The port 56 is defined by a cylindrical inner port surface 58 and a cylindrical outer port surface 60 and extends proximally from the center of the proximal end of the pneumatic piston chamber 24. A distal portion of a cylindrical inner valve surface 62 of the valve 48 is attached to the cylindrical outer port surface 60 of the port 56. A cylindrical outer valve surface 64 of the valve 48 is slidably located within the valve switch 50. The valve switch latch 54 is pivotably mounted to the proximal end of a valve switch plate 66 by a pin 68, which in turn is attached to the proximal end of the pneumatic piston chamber 24.

[0051] Referring again to Figure 1 , the valve switch latch 54 is rotated laterally inward and toward the central longitudinal axis of the valve 48 by a latch spring (not shown) about the pin 68. The valve switch spring 52 is located between the distal end of the housing end cap 70 and the proximal end of an outer cylindrical flange 72 on a cylindrical outer valve switch surface 74 of the valve switch 50 and abuts the distal end of the housing end cap 70 and the proximal end of the outer cylindrical flange 72. The valve switch spring 52 exerts a force on the proximal end of the outer cylindrical flange 72 of the valve switch 50, causing the distal end of the outer cylindrical flange 72 to abuttingly engage with proximal portions of four retaining flanges 76 of a cylindrical retainer 78 (as shown in Figure 5 , which is attached to the proximal end wall 46 of the housing 14. As a result, the valve switch 50 is biased in the position shown. As shown in Figure 5 , the retaining flanges 76 are attached to the retainer 78 by retaining flange supports 79. The retaining flange supports 79 are equally spaced around the perimeter of the retainer 78. Referring to Figure 2 and Figure 5 , this spacing allows the four valve switch latches 54 to move proximally and distally between the respective adjacent retaining flange supports 79 without restriction. Referring to Figure 2 , as described herein, the valve switch spring 52 is configured to move the valve switch 50 from the position in which the valve 48 is closed to the position in which the valve 48 is open. While the valve switch spring 52 is a spring, any suitable mechanism configured to move the valve switch 50 from the position in which the valve 48 is closed to the position in which the valve 48 is open is within the scope of the present disclosure. For example, a resilient member other than a spring can be utilized. Also as described herein, the rubber seal 80 of the valve switch 50 forms an air-tight seal configured to prevent any pressurized gas provided to the valve assembly 16 from entering the injection drive assembly 12 or escaping from the valve switch 50 when the valve 48 is in the position shown.

[0052] The injection cycle of the injection device 10 and the method of using the injection device 10 will now be described with reference to the exemplary embodiment shown in the drawings. Prior to use, the components of the injection device 10 are in Figure 1The user of the injection device 10 can grasp the handle 82 of the injection device 10. The safety (on / off) pin 83 is switched to the“on” position to enable the user to press the safety lever 84. The user then presses the safety lever 84 to enable the injection device 10 to operate, in particular to enable the pneumatic piston chamber 24 to move unrestricted within the housing 14. Pressurized gas (not shown) is supplied to the valve assembly 16 through the gas adapter 86 at a constant pressure. Since the valve 48 is in the closed position, the pressurized gas supplied to the valve assembly cannot enter the injection drive assembly 12 and cannot escape from the valve switch 50. The pressurized gas cannot enter the injection drive assembly because it cannot pass through the valve barrier 88. Furthermore, although the pressurized gas can exit the valve 48 via the valve bypass opening 90, the rubber seal 80 of the valve switch 50 forms an airtight seal that prevents the pressurized gas from exiting the valve switch 50 and entering the injection drive assembly.

[0053] The nozzle 92 attached to and in axial alignment with the dose chamber 30 abuts against and presses against the subject to be injected, thereby compressing the actuation return spring 18 and causing the injection drive assembly 12 and the valve assembly 16 to move proximally towards the proximal end of the housing 14 until they reach the Figure 3 position shown. During this movement, the proximal valve switch engagement portion 94 of the valve switch latch 54 comes into contact and abutting engagement with the distal end of the outer cylindrical flange 72 of the valve switch 50, thereby causing the valve switch to move proximally to the Figure 3 position shown. Once the injection drive assembly 12 and the valve assembly 16 are in the Figure 3 position shown, the actuation return spring 18 and the valve switch spring 52 are fully compressed or cocked. Since the distal housing engagement structure 96 of the valve switch latch 54 is in abutting contact with the cylindrical latch engagement sidewall 98 attached to the proximal end wall 46 of the housing 14, the valve switch latch 54 rotates laterally outwardly about the pin 68 to the Figure 3 position shown once the actuation return spring 18 and the valve switch spring 52 are fully cocked.

[0054] Once the valve switch latch 54 no longer releasably retains the valve switch 50 to restrict its movement distally, the valve switch 50 is moved rapidly distally from the Figure 3 position shown with the valve 48 closed to the Figure 4 position shown with the valve 48 open due to the decompression of the valve switch spring 52. The distal movement of the valve switch 50 is limited by the abutting engagement of the distal end of the outer cylindrical flange 72 of the valve switch 50 with the proximal portions of the four retaining walls 76 of the retainer 78 (as shown in Figure 5 the position shown). The valve 48 is in the closed position shown with the valve switch 50 in the Figure 3 position shown with the valve switch 50 in the Figure 4The speed of movement between the illustrated open positions is independent of control by the user of the injection device 10; in other words, the user of the injection device 10 cannot vary or manipulate the speed of movement of the valve switch 50. For example, the user causes the injection drive assembly 12 and the valve assembly 16 to move from Figure 1 the illustrated position to Figure 3 The speed of movement between the illustrated positions has no effect on the speed of movement of the valve 48 from the closed position to the open position.

[0055] It should be appreciated that the valve switch spring 52 can be configured to be fully cocked, rather than as illustrated and described herein. For example, the valve switch spring 52 can be configured to be manually cocked and released by the user. In such an embodiment, the pneumatic piston chamber 24 does not necessarily have to be slidably disposed within the housing 14, such that movement of the pneumatic piston chamber 24 does not necessarily actuate the valve switch spring 52, and the injection device 10 does not necessarily include the actuation return spring 18.

[0056] Upon movement of the valve switch 50 to Figure 4 As the valve 48 is illustrated in the open position, pressurized gas (not shown) supplied to the valve assembly 16 through the gas adapter 86 is immediately released through the port 56 to the injection drive assembly 12 via the valve 48. More specifically, the pressurized gas is immediately supplied to the portion of the pneumatic piston chamber 24 proximal to the pneumatic piston 20, where the pressurized gas is immediately available to begin the injection cycle. The pressurized gas enters the proximal portion of the valve 48 from the gas adapter 86. Once the pressurized gas is in the proximal portion of the valve 48, it exits the valve 48 through the valve bypass opening 90 (extending between the inner valve surface 62 and the outer valve surface 64) and re-enters the distal portion of the valve 48 through the valve vent 100 (also extending between the inner valve surface 62 and the outer valve surface 64), thereby bypassing the valve barrier 88. Since the valve bypass opening 90 and the valve vent 100 are located between the rubber seal 80 of the valve switch 50, respectively, the pressurized gas cannot escape from the valve switch 50, and all of the pressurized gas is directed to the pneumatic piston chamber cavity 38.

[0057] Since the valve switch 50 is moved quickly from the valve closed position to the valve open position, pressurized gas is provided to the pneumatic piston chamber 38 at a high gas supply rate. As the pressurized gas enters the pneumatic piston chamber 38, it exerts a force on the proximal end of the pneumatic piston 20 that is sufficient to overcome the limited force exerted by the pneumatic piston return spring 22 on the distal end of the pneumatic piston 20. As a result, the pneumatic piston 20 is quickly moved in the distal direction from Figure 4 the illustrated position to Figure 2 the illustrated post-injection position, resulting in compression of the pneumatic piston return spring 22, as Figure 2As shown. Initially, the acceleration of the pneumatic piston 20 is not influenced by the dose (not shown) contained in the dose chamber cavity 40 or the injector piston 26, as the pneumatic piston 20 is spaced apart from the injector piston 26 and is not directly or indirectly attached to the injector piston 26. In other words, initially, neither the injector piston 26 nor the dose (not shown) in the dose chamber cavity 40 present any resistance to the distal movement and acceleration of the pneumatic piston 20.

[0058] As the pneumatic piston 20 moves distally, it gains kinetic energy and the pneumatic piston 20 strikes the spherical proximal end 102 of the injector piston 26, thereby transferring some of its kinetic energy to the injector piston 26. The force exerted by the pneumatic piston 20 on the injector piston 26 is sufficient to overcome the limited force exerted by the injector piston return spring 28 on the distal end of the spring plate 42, as a result, the injector piston 26 is forced to move rapidly distally, thereby compressing the injector piston return spring 28. The rapid distal movement of the injector piston 26 and the pneumatic piston 20 causes the dose (not shown) contained in the dose chamber cavity 40 to rapidly reach a hydraulic peak, and the injector piston 26 to move distally to Figure 2 The position shown results in the dose being expelled through the outlet valve 104 and the nozzle 92 and into the subject. The inlet valve 106 is configured to allow liquid (not shown) to be drawn into the dose chamber cavity 40 and is also configured to prevent pressurized liquid within the dose chamber cavity 40 from escaping through the inlet valve 106.

[0059] As described above, the pneumatic piston return spring 22 and the injector piston return spring 28 are not energy accumulators. This is because, although these components do serve to place the respective pneumatic piston 20 and injector piston 26 in the pre-injection position and must be compressed during the injection cycle to move the injection drive assembly 12 to the post-injection position, they do not store energy as potential energy prior to the start of the injection cycle until the stored potential energy reaches a predetermined threshold or is manually released, and then make the energy available to start the injection cycle. Instead, the energy provided to the injection drive assembly 12 to start the injection is provided from the opposite direction and is immediately available to start the injection cycle.

[0060] Once the injection is complete and the injection drive assembly 12 is in Figure 2 The post-injection position shown, the pneumatic piston 20 and the injector piston 26 are in their most distal positions, respectively, and the pneumatic piston 20 is in abutting contact with the spherical end 102 of the injector piston 26. The pneumatic piston return spring 22, the injector piston return spring 28, and the actuation return spring 18 are all fully compressed or cocked. After an injection with the injection device 10, the nozzle 92 is moved in a direction away from the injection subject, which allows the actuation return spring 18 to decompress, thereby forcing the pneumatic piston chamber 24 to move distally and return to Figure 1 the pre-injection position shown.

[0061] As the pneumatic piston chamber 24 moves distally, the valve 48 and valve switch latch 54 attached to the pneumatic piston chamber 24 as described above also move distally. As a result, the distal housing engagement structure 96 of the valve switch latch 54 disengages from abutting contact with the cylindrical latch engagement side wall, allowing the valve switch latch to rotate laterally inward about the pin 68 to the position shown. In addition, the valve 48 returns to the closed position, causing the valve vent 100 to disengage from alignment with the valve switch 50, such that the valve vent 100 is not positioned between the rubber seals 80 of the valve switch 50. In this position, as the pneumatic piston return spring 22 decompresses and forces the pneumatic piston 20 to move proximally, residual pressurized gas contained within the pneumatic piston chamber 24 can escape through the valve vent 100.

[0062] As the pneumatic piston 20 disengages from abutting contact with the injectate piston 26, the injectate piston return spring 28 decompresses and forces the injectate piston 26 to move proximally and return to the pre-injection position, at which time all components of the injection drive assembly 12 are in Figure 1 the pre-injection position shown. The proximal movement of the injectate piston 26 creates a negative pressure within the dose chamber 30, which in turn causes liquid (not shown) to be drawn into the dose chamber cavity 40 from the inlet valve 106. As a result, the injection device 10 is now ready to complete another injection cycle. Although only one valve bypass opening 90 and one valve vent 100 are shown, the valve 48 includes two valve bypass openings 90 and two valve vents 100. Although the valve 48 includes two valve bypass openings 90, the valve 48 can also have only one or more than two valve bypass openings 90. Similarly, although the valve includes two valve vents 100, the valve 48 can also have only one or more than two valve vents 100. In addition, it should be understood that although the operation of the injection device 10 is described in conjunction with one embodiment of the valve assembly 16 in combination with certain other valves and openings, other types of valves and venting devices can be used to control the flow of gas into and out of the injection device 10. Any valve assembly configured to provide pressurized gas to the injection drive assembly 12 to initiate an injection cycle and allow the pressurized gas to escape from the injection drive assembly 12 when the pneumatic piston 20 and the injectate piston 26 return to the pre-injection position are within the scope of the present invention. In addition, in certain other embodiments, the force can be provided without a valve.

[0063] From the foregoing, it will be seen that this invention is one well adapted to attain all the ends and objects hereinabove set forth, together with other advantages which are obvious or inherent to the invention.

[0064] As many possible embodiments can be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is presented by way of example and not limitation, and the foregoing

[0065] While some embodiments are illustrated and discussed above, it will be appreciated that various modifications and alterations can be made to the embodiments without departing from the scope of the application. Accordingly, it is not intended that the application be limited, except as by the appended claims.

Claims

1. An injection device comprising: an injection drive assembly, wherein the injection drive assembly comprises: a pneumatic piston chamber; a dose chamber; a pneumatic piston slidably disposed in the pneumatic piston chamber; and an injectate piston slidably disposed in the dose chamber; wherein the injection drive assembly is movable between a pre-injection position and a post-injection position; and wherein the injection drive assembly is configured such that any energy resulting from the application of a force to the injection drive assembly is immediately available to push the pneumatic piston and the injectate piston without first storing the energy as potential energy until the stored potential energy reaches a predetermined threshold or is manually released, wherein the pneumatic piston and the injectate piston are not directly or indirectly attached to one another, the injection device further comprising a separate respective resilient member for each of the pneumatic piston and the injectate piston, wherein each respective resilient member is configured to place each of the pneumatic piston and the injectate piston in the pre-injection position, wherein, when the injection drive assembly is in the pre-injection position, the pneumatic piston and the injectate piston are spaced apart from one another.

2. The injection device of claim 1, wherein the injection drive assembly does not include an accumulator.

3. The injection device of claim 2, wherein the accumulator is a pressure accumulator.

4. The injection device of claim 3, wherein the pressure accumulator is a pressurized fluid pressure accumulator.

5. The injection device of claim 3, wherein the pneumatic piston is not configured to operate as a pressure accumulator.

6. The injection device of any one of claims 3 and 5, wherein the pneumatic piston chamber is not configured to operate as a pressure accumulator.

7. The injection device of any one of claims 1-5, wherein the injection drive assembly does not include a lock configured to hold the injection drive assembly in the pre-injection position.

8. The injection device of claim 7, wherein the pneumatic piston is not held in the pre-injection position with a lock.

9. The injection device of claim 1, wherein the injection drive assembly is configured such that energy resulting from the application of a force to the injection drive assembly is immediately available to move the pneumatic piston through a space between the pneumatic piston and the injectate piston.

10. The injection device of claim 1, wherein the injection drive assembly is configured such that the force applied to the injection drive assembly and the movement of the pneumatic piston results in kinetic energy sufficient to push the injectate piston forward.

11. The injection device of any of claims 1-5, wherein, the pneumatic piston and the injectate piston are each in their proximal-most position when the injection drive assembly is in the pre-injection position.

12. The injection device of any of claims 1-5, wherein, the pneumatic piston and the injectate piston are each in their distal-most position when the injection drive assembly is in the post-injection position.

13. The injection device of claim 1, wherein each resilient member is a spring.

14. The injection device of any one of claims 1-5, wherein the force is provided by a pressurized fluid.

15. The injection device of claim 14, wherein the pressurized fluid is selected from the group consisting of a pressurized gas, a pressurized liquid, and combinations thereof.

16. The injection device of any one of claims 1-5, further comprising: a valve assembly; wherein the valve assembly comprises a valve; wherein the valve is movable between a closed position and an open position; wherein the valve is configured to provide pressurized fluid to the injection drive assembly when the valve is in the open position; and wherein the speed of movement of the valve between the closed position and the open position is independent of control by a user of the injection device.

17. The injection device of claim 16, wherein the valve assembly further comprises: a valve switch resilient member; and a valve switch; wherein the valve switch resilient member is operable to move the valve switch from a valve closed position to a valve open position.

18. The injection device of claim 17, wherein the valve switch resilient member is a spring.

19. The injection device of any one of claims 17-18, wherein the valve assembly further comprises: a valve switch latch; wherein the valve switch latch is configured to releasably hold the valve switch in a valve closed position.

20. The injection device of any one of claims 17-18, further comprising: a pneumatic piston chamber resilient member; wherein the pneumatic piston chamber is movable between a pre-actuation position and an actuated position; and wherein the pneumatic piston chamber resilient member is configured to place the pneumatic piston chamber in the pre-actuation position.

21. The injection device of claim 20, wherein the valve switch resilient member is configured to be actuated by movement of the pneumatic piston chamber to the actuated position.

22. The injection device of claim 20, wherein the pneumatic piston chamber resilient member is a spring.

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