Dosing Mechanism For Multi-Shot Injection Device Comprising Flexible Ratchet Element

What is this patent about?

’376 is related to the field of dose-controlled injection devices, specifically those used for multi-shot applications. These devices, often resembling pens, allow patients to self-administer variable doses of medication. A common design involves a drive spring that is tensioned when a dose is set, and a mechanism to maintain that tension until the dose is delivered. The background highlights the need for robust and user-friendly designs, especially for elderly patients who may have difficulty manipulating the device or understanding its operation.

The underlying idea behind ’376 is to provide an improved mechanism for dialing down a set dose in a multi-shot injection device. This is achieved through a novel ratchet mechanism that allows for controlled release of the drive spring's stored energy. The key insight is to use a flexible ratchet element with multiple teeth engaging a fixed toothed element, and to actively disengage these teeth by applying a torque that elastically deforms the flexible element, thus releasing the ratchet lock.

The claims of ’376 focus on a dose-controlled multi-shot injection device featuring a housing, a dose setting mechanism, a drive spring, a rotatable dose setting handle, and a ratchet mechanism. The ratchet mechanism is further defined by a fixed element with circumferential teeth, a flexible element with teeth engaging the fixed element, and a rotational element that, when torqued, radially deforms the flexible element to disengage the teeth. Claim 1 requires cams that deflect the perimeter of the flexible ratchet element. Claim 12 requires the fixed ratchet element to have teeth on its outer circumference and the flexible ratchet element to be ring-shaped with teeth on its inner circumference.

In practice, the user sets a dose by rotating the handle, which tensions the drive spring and engages the ratchet mechanism. To reduce the dose, the user rotates the handle in the opposite direction. This rotation actuates the rotational element, which then applies forces to the flexible ratchet element. These forces cause the flexible element to deform, effectively reducing the distance between its teeth and disengaging them from the fixed element's teeth. This allows the user to dial down the dose in a controlled manner, releasing the spring tension incrementally.

This design differentiates itself from prior approaches by actively releasing the ratchet lock through elastic deformation of the flexible ratchet element. Older designs might have relied on overcoming the ratchet lock through brute force, which could be difficult for users with limited strength. By using a cam-actuated deformation , the ’376 design provides a more user-friendly and controlled method for adjusting the dose, particularly beneficial for patients who need to fine-tune their medication dosage.