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Publication Number
US-8747367-B2
Publication Date
2014-06-10
Expiration Date
Abstract
An injection apparatus has a barrel (50) that is adapted to receive a container (108) with injection fluid (110). It further comprises a piston rod (98), provided with a thread (100), for expelling injection fluid (110) from such a container (108), which piston rod (98) is guided relative to the barrel (50) in the axial direction (112, 114). Additionally provided is a threaded part (122) whose thread (120) is in engagement with the thread (100) of the piston rod (98), which threaded part (122) is rotatable relative to the piston rod (98) and relative to the barrel (50) in order to set an injection dose, and, during an injection operation, is prevented from rotating relative to the piston rod (98).
Core Innovation
The invention relates to an injection apparatus in which a piston rod having a thread is non-rotatably guided relative to a housing and expels injection fluid from a container. Expelling is performed by threaded engagement between the piston rod thread and a threaded part, with the position of the threaded part relative to the housing being adjustable. The threaded part is configured to translate axially during dose-setting and injection, while the piston rod is guided along the longitudinal axis in a non-rotating manner relative to the housing.
A setting member is provided for setting an injection dose by rotation of the setting member. A coupling is arranged between the setting member and the threaded part such that the coupling is closed during setting of the injection dose and open during an injection process, enabling the threaded part to be rotatable relative to the piston rod and relative to the housing during dose-setting. During the injection process, the threaded part moves axially relative to the housing in an injection direction, while being hindered against rotation relative to the piston rod, so the previously set dose is converted into expelled fluid quantity.
The invention further includes a pushing member connected to the housing via a first drive connection and to the setting member via a second drive connection. This connection arrangement causes the pushing member to move relative to the housing in a predetermined direction when the setting member is moved by rotation relative to the housing, and the pushing member pushes the threaded member and the piston rod in an injection direction during an injection process. The disclosed embodiments include a dose-setting and injection mechanism with splines and detent clicks, coupling behavior that is closed during dose-setting and opened during actuation, and variants using a torsional spring and displacement member/low-friction guidance to support dose setting and return behavior.
Claims Coverage
The independent claim is clm-00001. It defines a threaded, non-rotatably guided piston rod with an axially movable threaded part, a rotational setting member, and a coupling that changes from closed during dose-setting to open during injection so that dose-setting allows relative rotation while injection hinders relative rotation.
Non-rotatably guided threaded piston rod with adjustable threaded part
A piston rod having a thread serves, in operation, for expelling injection fluid from a container and is non-rotatably guided relative to the housing for movement in a longitudinal-axis direction, while a threaded part with a first thread engages the piston-rod thread and has an adjustable position relative to the housing.
Rotational dose setting with coupling changing from closed to open
A setting member is provided for setting an injection dose by rotation of the setting member, and a coupling arranged between the setting member and the threaded part is closed during setting of the injection dose and open during an injection process so the threaded part is rotatable relative to the piston rod and relative to the housing for dose-setting, moves in the longitudinal-axis direction during a dose-setting operation, and during injection moves axially relative to the housing in an injection direction but is hindered against rotation relative to the piston rod.
Adjustable combined length reset by relative housing and setting-member rotation
The setting member is rotatable arranged in the housing such that, for setting an injection dose, a combined length of the housing and the setting member is adjustable from an initial combined length value by rotation of the housing and the setting member with respect to each other, and the combined length is resettable during an injection process to the initial combined length value by rotating the housing and the setting member with respect to each other.
Pushing member driven by first and second drive connections
A pushing member is connected to the housing via a first drive connection and to the setting member via a second drive connection so that the pushing member moves relative to the housing in a predetermined direction when the setting member is moved likewise in that predetermined direction by rotation relative to the housing, and pushes the threaded member and the piston rod in an injection direction during an injection process.
Across the independent claim, dose setting is achieved by rotating a setting member coupled to a threaded part that is allowed to rotate relative to the piston rod during dose-setting, while injection converts the set dose by axially moving the threaded part/piston rod during injection with the threaded part hindered against rotation relative to the piston rod. Resetting of the combined length via relative rotation of the housing and setting member and a pushing-member drive via first/second drive connections complete the mechanism.
Stated Advantages
Not explicitly described in patent.
Documented Applications
Not explicitly described in patent.
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