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Intermediate component between stack and needle: modular dynamic sealing Disclosure Number: IPCOM000021530D
Original Publication Date: 2004-Feb-25
Included in the Prior Art Database: 2004-Feb-25

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By an intermediate element between stack and needle, the bellows-pin (see element (3) in figure 1), it is possible to reduce the length of the needle of a piezo injector in a direct injection system. It can be reduced up to 12 mm. This represents a big improvement regarding the stretch of the needle. The dynamic sealing (bellows; element (2), fig. 1) can be welded in an easy way by choosing a proper pin material. This pin has to be welded on the spring washer (element (5), fig. 1) as well. Therefore, a good compromise between bellows-ring (element (7), fig. 1) material and spring washer (element (5), fig. 1) material is necessary. The main advantage is that in this way a welding between martensitic and austenic material can be avoided. The welding between martensitic steel (needle material) and austenitic steel (bellows-ring material) with the hardness needed on the component is very difficult. The solution avoid to weld the bellows directly on the needle (element (4), fig. 1). Moreover the bellows welding to the pin can be done without having the cartridge and needle on the jaw-chuck of the welding machine. In this way the contamination during the welding process can not influence the tip area.