FR2777338A1 - SOLENOID VALVE - Google Patents

Abstract

The invention concerns an electromagnetic check valve comprising a plate (3) arranged to co-operate with an electromagnet core (1). Said plate comprises a plurality of protrusions, for example elastic teeth (7) projecting on said core side. Said blade can be made of elastomer, overmoulded with a sealing joint and a friction ring for a return spring. The invention is useful for reducing operating noise, in particular in motor vehicles.

Description

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SOLENOID VALVE

  The present invention relates to a solenoid valve, and more particularly such a valve comprising a blade arranged to cooperate

with an electromagnet core.

  Solenoid valves are used in particular in fuel mixture supply systems of internal combustion engines, in

  particularly in the field of motor vehicles.

  o10 A solenoid valve typically comprises an electromagnetic coil wound on the hub of a plastic bobbin and a metal core disposed inside this hub. A valve is arranged opposite the core to be moved axially by electromagnetic forces, from a position where it closes a flow duct of

  fluid to another position in which the conduit is open.

  In these solenoid valves, the coil is supplied with chopped current with a duty cycle which can vary from 0 to 100%. The valve is kept normally closed by a spring. When current flows through the coil, the valve opens. The valve therefore remains open for a longer or shorter time at each cycle depending on the duty cycle. We therefore regulate the flow using

of the duty cycle.

  The problem with this type of solenoid valve lies in the significant noise level generated by the repeated impacts of the valve on the core when it is opened. The present invention aims to overcome this drawback, by providing a solenoid valve considerably quieter than those of the prior art. For this purpose, the invention relates to a solenoid valve comprising a blade arranged to cooperate with an electromagnet core, characterized in that said blade comprises a plurality of

  extra thicknesses of elastic material projecting from the side of said core.

  When the solenoid valve is energized, at each cycle, the blade comes into contact with the core via the extra thicknesses which

  absorb shock and therefore reduce noise.

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  In addition, the extra thicknesses are more or less crushed as a function of the electromagnetic force exerted by the core on the blade. If the excess thicknesses are not slightly crushed, the return stroke of the blade towards its seat at the power cut is lower and the speed reached is less important. This also results in noise reduction, mainly at

low duty cycles.

  In a particular embodiment, said extra thicknesses

include pins.

  In another particular embodiment, said extra thicknesses

include crown arches.

  More particularly, the blade may include extra thicknesses of

different heights.

  Even more particularly, said extra thicknesses may include studs projecting from crown arcs themselves in

protrusion on the blade.

  It will be observed that the crown arcs can, in certain modes

  of realization, join to form a complete crown.

  Because of these differences in height, and therefore of crushing by electromagnetic forces, the extra thicknesses repel the blade not symmetrically when the current is cut off. The blade therefore moves askew with respect to a perpendicular to its surface. It comes into contact with the nucleus at a point and not flat, and does not recover flat until later after part of the impact energy has been dissipated. Again the noise is reduced.

  The extra thicknesses can for example be overmolded on the blade.

  More particularly, the extra thicknesses can be overmolded with a seal on the other side of the blade and / or with a gasket.

  friction for a return spring.

  A particular embodiment of the invention will now be described, by way of nonlimiting example, with reference to the appended schematic drawings in which: - Figure 1 is a view in axial section of a part of a solenoid valve comprising a valve according to the invention; and - Figure 2 is an axial sectional view of the larger valve

ladder.

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  FIG. 1 shows the magnetic core 1 of the electromagnet of a solenoid valve of known type. This electromagnet is supplied as indicated above with chopped current, the duty cycle of which is

  determined so as to obtain a given flow rate.

  A tube 2 opens into the body of the solenoid valve, this tube being capable of being closed by a valve 3 constituted by a mild steel blade guided in any suitable manner. The valve 3 is arranged opposite the end of the core 1, between this core and the pipe, to be attracted by this core during the phases of current flow,

way to open the tubing 2.

  A helical spring 4 is arranged to push the valve 4 against the action of electromagnetic forces, in the closed position against

  the end of the tube 2 which therefore forms a seat for the valve.

  A fluorinated elastomer is molded onto the valve 3. On the side of the tubing 2, this elastomer forms a seal 5. On the side of the magnetic core 1, the elastomer forms on the one hand a friction ring 6 intended for receive the end of the spring 4, and on the other hand a set of

protruding thicknesses 7.

  The extra thicknesses 7 are here generally shaped pins

  conical, with a substantially spherical point.

  The extra thicknesses could also form crown arcs, for example of substantially triangular radial section, coaxial with the core

magnetic 1 and to tubing 2.

  Similarly, the bases of the pins could be raised relative to

  to blade 3, the pins then protruding on crown arcs.

  The valve 3 is drilled in its center so that all the elements of the overmolding are made in one piece. To this end, the pins 7 are joined by a crown of material embedded in the steel of the valve, and this latter crown is connected to the crown 6 by radial channels.

also embedded in steel.

  The pins are preferably distributed regularly around the axis of the valve 3. They are for example 8 in number, 4 long pins alternating with 4

short pimples.

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Claims (7)

  1- Solenoid valve comprising a blade (3) arranged to cooperate with an electromagnet core (1), characterized in that said blade comprises a plurality of thickeners (7) made of elastic material protruding from the side of said core.   2- A valve according to claim 1, wherein said extra thicknesses include pins.   3- A valve according to any one of claims 1 and 2, in   which said extra thicknesses comprise crown arcs.   4- A valve according to any one of claims 1 to 3, comprising   extra thicknesses of different heights.   - A valve according to claim 4, in which the said extra thicknesses comprise studs projecting from the crown arcs themselves in protrusion on the blade.   6- A valve according to any one of claims 1 to 5, wherein   said extra thicknesses are overmolded on the blade.   7- A valve according to claim 6, wherein said extra thicknesses   are overmolded with a seal (5) on the other side of the blade.   8- A valve according to any one of claims 6 and 7, in   which said extra thicknesses are overmolded with a lining of   friction (6) for a return spring (4).