Valves and valve actuation – Electrically actuated valve – Including solenoid
Patent
1994-05-11
1996-10-22
Lee, Kevin
Valves and valve actuation
Electrically actuated valve
Including solenoid
25112915, 2395854, F16K 3106, F02M 5106
Patent
active
055669204
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on a valve needle for an electromagnetically actuable valve and on a method for manufacturing a valve needle as set forth hereinafter. The German Offenlegungschrift DE-A 40 08 675 discloses a valve needle for an electromagnetically actuable valve which consists of an armature section, a valve closing element section and a valve sleeve section which connects the armature section to the valve closing element section. The armature section is connected to one end of the valve sleeve section by means of a first weld connection and the valve closing element section is connected to the other end of the valve sleeve section by means of a second weld connection. In order to manufacture the valve needle, two welding processes are therefore required, which lead to a relatively costly and expensive production of the valve needle. Additionally, there is the risk that, during the manufacture of the second weld connection between the valve closing element section and the tubular valve sleeve section, weld spatter formations are produced which become deposited on the inner wall of the tubular valve sleeve section and impair the functioning of the valve.
ADVANTAGES OF THE INVENTION
The valve needle according to the invention and the method according to the invention have, in comparison, the advantage that such a valve needle can be manufactured in a simple and cost-effective manner. The composition of the metal powder used can be simply adjusted here to give rise to optimum magnet properties of the armature section. The presence of sulphur and carbon which can have a disadvantageous effect on the quality of a weld between a valve closing element section and valve sleeve section which can be easily avoided.
By means of the measures specified in the herein, advantageous further developments and improvements of the valve needle and of the method are possible.
It is particularly advantageous if the longitudinal opening of the valve sleeve section has a partition near to its end facing the valve closing element section. In this way, a cavity is formed between the partition and the valve closing element section, in which cavity weld spatter formations, which are produced during the manufacturing of the weld connection between the valve closing element section and the valve sleeve section, are enclosed and cannot impair the functioning of the valve.
For good removal from the moulds used during the manufacture, it is advantageous if the valve sleeve section tapers starting from the armature section in the direction of the valve closing element section.
In order to reduce the weight of the valve needle, it is advantageous if recesses which extend in the direction of the longitudinal axis of the valve are formed in the wall of the longitudinal opening of the valve sleeve section so that the flow through the longitudinal opening of the valve sleeve section is not impaired.
The direct formation of a floor at the end of the valve sleeve section facing the valve closing element section also provides the advantage of keeping weld spatter formations out of the interior of the valve sleeve section.
A particularly advantageous design of the valve needle is produced then if it is manufactured with the armature section, the valve sleeve section and the valve closing element section as a preform according to the metal injection moulding method.
It is advantageous if a plastic binding agent is used as a binding agent and that this binding agent is removed from this preformby means of a thermal treatment of the preform. In this way, a particularly simple manufacture of a preform which forms the valve needle or the actuation part that already has a high degree of structural sealing is made possible.
It is particularly advantageous if the preform is hot-isostatically pressed after the sintering so that a particularly sealed structure of the valve needle and of the actuation part consisting of armature section and the valve sleeve section is obtained.
DRAWING
Exemplary embodiments of the invention are illustr
REFERENCES:
patent: 5002727 (1991-03-01), Okimoto et al.
patent: 5170987 (1992-12-01), Krauss et al.
Maier Martin
Naeger Thomas
Reiter Ferdinand
Romann Peter
Greigg Edwin E.
Griegg Ronald E.
Lee Kevin
Robert & Bosch GmbH
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