Valves and valve actuation – Electrically actuated valve – With means to bias valve open
Patent
1991-03-25
1992-06-23
Rosenthal, Arnold
Valves and valve actuation
Electrically actuated valve
With means to bias valve open
25112916, 25112917, F16K 3106
Patent
active
051236265
DESCRIPTION:
BRIEF SUMMARY
PRIOR ART
The invention is based on an electromagnetic on-off valve for controlling the opening area of a fluid line, in particular for fuel injection pumps. Such on-off valves, known for example from DE 37 32 553 A1, in which it is not a liquid but rather air which flows around the magnetic armature, have a relatively high switching speed since the magnetic armature which is very large in area no longer moves in the fluid and is thus hydraulically damped.
However, in the quickly switching solenoid valves a problem arises of a rebounding of the valve element after the closing of the valve. If such a solenoid valve is used in fuel injection pumps, the re-opening of the valve element results, due to its rebounding, in inadmissibly large leakage quantities of the injected fuel quantity. The rebounding of the valve can be limited to a noncritical value by designing the valve seat geometry such that, as result of the constricted flow when the valve closes, a sufficiently large damping force arises within the cover. However, this requires a high degree of production accuracy with respect to sealing surface angle differential and roughness of the surfaces on the valve seat and valve member.
ADVANTAGES OF THE INVENTION
The electromagnetic on-off valve has in contrast to the above, an advantage that, as a result of the oscillating in phase opposition of the two masses of the valve needle and magnetic armature, the rebound amplitude occurring at the valve element is very small and declines rapidly. The leakage quantities still occurring when using the valve in fuel injection pumps are thus extremely small and lie without exception in the tolerance range. When an extension rod is used for the elastic coupling of the magnetic armature and valve needle, the correct setting of the elastic coupling occurs by setting the pre-tension of the extension rod.
Advantageous further developments and improvements of the on-off valve specified herein are possible by means of the measures disclosed.
According to a preferred embodiment of the invention, the extension rod extends inside the hollow-cylindrical valve needle, into whose end facing the magnetic armature a terminating piece with a T-shaped cross-section projects, which terminating piece bears the magnetic armature on its cross piece and is thus supported on the valve needle and bears a threaded bore in its centre part. The extension rod is screwed into the centre part of the terminating piece at one end and is supported with its other end on the valve needle. By rotating, the extension rod can be screwed more or less deeply into the threaded bore and its pre-tension can thus be altered in such a way that the correct oscillation of the two masses in phase opposition is achieved. For this purpose it is necessary to measure the timing of the stroke of the magnetic armature and valve needle, which is readily possible with suitable devices.
According to a further embodiment of the invention, the centre part of the terminating piece bears an external thread on which an adapter sheath is screwed. The adapter sheath, on the one hand, secures the membrane which seals the electromagnet off with respect to the liquid and, on the other hand, is supported on the end side of the valve needle. The latter has the advantage that, on the closing of the valve, a gap forms, as a result of constricted flow, between the end side of the valve needle and the end side of the adapter sheath resting against it, in which gap energy is additionally destroyed, as a result of which the rebounding of the valve element is additionally reduced.
DRAWING
The invention is explained in greater detail in the subsequent description with reference to an exemplary embodiment illustrated in the drawing, in which:
FIG. 1 shows a longitudinal section of an electromagnetic on-off valve for a fuel injection pump,
FIGS. 2 and 3 show in each case a diagram of the timing of the stroke of the valve needle and magnetic armature when the elastic coupling between valve needle and magnetic armature is correctly adjusted
REFERENCES:
patent: 2697581 (1954-12-01), Ray
patent: 4957275 (1990-09-01), Homes
Baumel Ehrtfried
Muller Martin
Rembold Helmut
Schlagmuller Walter
Greigg Edwin E.
Greigg Ronald E.
Robert & Bosch GmbH
Rosenthal Arnold
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