Patent ID: 8662420

Claim:
A valve body of a fluid injector comprising: a needle extending in an axial direction; a cartridge with a recess which takes in the needle; and a seat plate disposed on one end of the recess, comprising a needle seat for the needle, wherein the needle includes a seat part with a sealing area that rests on the needle seat if it is pushed against the needle seat, wherein the needle includes a cavity comprising a blind hole disposed radially inwards from the sealing area and having an axial length covering in axial extension the sealing area, the cavity defining a circumferential inner sidewall that extends along the axial length and an end opposite the sealing area of the needle, wherein the cavity makes the seat part more flexible in the sealing area as compared to an identical seat part without a cavity, such that ends of the seat part around the cavity flex inwardly due to micrometric deformations of the seat part when engaged in the needle seat, and wherein the cavity is at least partially filled with a material affixed to the circumferential inner sidewall and the end of the cavity such that at least a portion of the material is located between the ends of the seat part that flex inwardly, the material having a stiffness less than a stiffness of the seat part in order to achieve a desired flexibility of the seat part, whereby a seal is formed between the seat part and the needle seat when the seat part is engaged in the needle seat.