Metal working – Method of mechanical manufacture – Electrical device making
Patent
1998-12-01
2000-05-09
Harrison, Jessica J.
Metal working
Method of mechanical manufacture
Electrical device making
29598, 2989807, 310 43, 600 16, H02K 1500
Patent
active
060585935
DESCRIPTION:
BRIEF SUMMARY
The present invention refers to a method for manufacturing a micro motor, in particular for a blood pump that may be operated in an intracardiac or intravascular manner.
Intravascular blood pumps are known that are introduced into the body by punctuating a blood vessel of the vascular system and subsequently advancing the blood pump through the blood vessel to the desired location inside the body. The maximum diameter of such elements introduced into blood vessels is limited since the pump has to be pushed through the blood vessel system from the introduction site to the application site. Further, the blood pump may only have small axial dimensions so that the pump is not obstructed when being advanced through bends of the vessel system. When a blood pump is advanced to the heart for assisting the left heart side, the outer diameter must not exceed 8.0 mm and the rigid length of the pump must not exceed 4 cm so that the pump can be pushed through the aortic arch into the heart.
From EP 0 157 871 D1 and EP 0 397 668, intravascular cardiac pumps are known, where the pump portion and the motor portion are constructed separately and are connected by a flexible shaft. While the pump portion is introduced into the body, the rotor portion remains outside the body.
WO94/09835 (Jarvik) describes a pump device for cardiac support, wherein at least one pump comprises a pump portion and a motor portion that are rigidly connected, the pump portion being introduced into one ventricle of the opened heart, whereas the motor portion remains outside the heart.
There is a need for intracardiac or intravascular pumps, i.e. pumps that may be arranged entirely and may be operated within the heart or a blood vessel, the motor portion and the pump portion thereof forming a rigid unit. However, this requires that each of both portions can be manufactured in extremely small size and with high precision.
In WO97/37696 (published posteriorly), an intravascular blood pump is described, wherein the drive portion and the pump portion form a rigid unit connected to a catheter. The dimensions of the blood pump are small enough to allow for the pump to be pushed through a blood vessel to the destination or to be operated in the blood vessel. In the intravascular blood pump, the pump portion and the drive portion are of substantially the same diameter of no more than about 5-7 mm. In addition, the pump may be prolongated by means of a flexible hose extending its effective length.
In a blood pump to be operated within the body, high precision is required from the drive and pump portions. In particular, it must be guaranteed that the impeller of the rotary pump is very accurately centered in the pump housing and that the pump housing is also very accurately positioned with respect to the motor housing. When these requirements are not met exactly, damage to the blood and thrombogenesis may occur due to shear forces. On the other hand, it must be taken into consideration that such blood pumps are generally used as one-way articles and, therefore, should be economical to manufacture.
It is the object of the present invention to provide a method for manufacturing a micro motor for use in a blood pump, the method allowing to manufacture a micro motor at low cost and with high precision.
According to the invention, the object is solved with the features of claim 1.
In the present method, the stator of the motor is manufactured by pushing the stator parts onto a mandrel and placing them into an injection mold together with the mandrel. Polymeric material is injected into the injection mold, the material enclosing the stator parts and later forming the motor housing. Thus, a stator centered on the mandrel is obtained, which has its parts embedded in a housing that is also centered on the mandrel. The mandrel may be positioned very accurately in the injection mold. In general, the stator parts are coils and soft-iron yoke sheets for magnetic yokes. The present method makes it possible to strictly meet rigorous tolerance requirements by not building th
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Harrison Jessica J.
Impella Cardiotechnick GmbH
Trinh Minh
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