GB2245764A

GB2245764A - Solenoid operated fuel injection valves

Info

Publication number: GB2245764A
Application number: GB9113309A
Authority: GB
Inventors: Francesco Morini; Mirco Vignoli
Original assignee: Weber SRL
Current assignee: Weber SRL
Priority date: 1990-06-29
Filing date: 1991-06-20
Publication date: 1992-01-08
Also published as: IT9053109V0; FR2663992A1; IT220460Z2; GB9113309D0; DE4120947A1; IT9053109U1

Abstract

The valve comprises an injection nozzle (2) in which is formed a fuel injection orifice (3) controlled by an axially mobile plunger (4), an anchor (6) secured to the plunger (4), a core (7) housed in the valve body (1) and designed to attract the anchor (6), and an excitation coil (8) housed in the valve body (1). The coil (8) comprises a number of turns of insulated, electrically conductive wire arranged in parallel layers of short axial length (b), the number of the layers being so selected that the radial thickness (a) of the layers is greater than the axial length (b) of each layer. <IMAGE>

Description

2, -, I- ES '7 CE,.4 PERFECTED ELECTROMAGNETIC FUEL METERING AND ATOMIZING

VALVE FOR AN INTERNAL C9MBUSTION ENGINE SUPPLY DEVICE The present invention relates to a perfected fuel metering and atomizing valve comprising an injection nozzle in which is formed a fuel injection orifice; a plunger designed to move axially between a closed and open position wherein the injection orifice is respectively closed and opened; an anchor secured to the plunger; a core housed inside the valve body and designed to attract the anchor; and an excitation coil also housed inside the valve body.

on valves of the aforementioned type, the excitation coil comprises a number of turns of insulated, electrically conductive wire substantially coaxial with the core.

Said turns are arranged in parallel layers of a given axial length, and the number of which is so selected that the radial thickness of the layers is less than the axial length of each individual layer.

The above wire layer arrangement is the best for enabling fast. troublefree, automatic production of the coil, by winding each layer on top of the underlying one as the coil is moved axially on a mandrel (or by feeding the wire itself axially along the coil). At the end of each layer. axial displacement of the coil or wire is reversed for switching to the next layer. Though this provides for high-speed winding of even fairly long layers. the time required for switching from one layer to the next is far from negligible. consequently. for reducing the total time required for winding the coil, the current tendency is to produce fairly long coils of limited radial thickness, i.e. very few superimposed layers.

Moreover, a coil longer than its radial thickness provides for greater compactness and uniformity and. when embedded inside a ring of plastic material, requires no particular handling to prevent the turns in the various superimposed layers from being dislodged from the initial winding position.

Fuel metering and atomizing valves featuring coils of the above type. however. have been found to provide for a poor degree of operating response. In fact. the magnetic flux generated by such coils through the core, anchor and part of the valve body fails to provide for high-speed pull between the anchor and the core. as required by the fuel metering and atomizing valves of supply devices employed on competition engines or high-performance engines in general.

-j 3 - It is an object of the present invention to provide a perfected valve of the aforementioned type designed to overcome the aforementioned drawback, i.e. designed to enable a high degree of operating response.

According to the present invention, there is provided an electromagnetic fuel metering and atomizing valve for an internal combustion engine supply device, said valve comprising an injection nozzle in which is formed a fuel injection orifice; a plunger designed to move axially between a closed and open position wherein said orifice is respectively closed and opened; an anchor secured to said plunger; a core housed in the valve body and designed to attract said anchor; and an excitation coil housed in said body and comprising a number of turns of insulated, electrically conductive wire substantially coaxial with said core; characterised by the fact that said turns are arranged in parallel layers of short axial length, and the number of which is so selected that the radial thickness of said layers is greater than said axial length of each said layer.

A non-limiting embodiment of the present invention will be described by way of example with reference to the accompanying drawing, which shows a partially sectioned side view of a perfected fuel metering and atomizing valve in accordance with the present invention.

The valve according to the present invention substantially comprises a body 1 the bottom portion of which is fitted with a nozzle 2 having a fuel injection e 11 orifice 3 and inside which a plunger 4 moves axially between a closed position (shown in the drawing) wherein the front end 5 of plunger 4 closes orifice 3, and an open position wherein said orifice 3 is opened. The valve also comprises an annular anchor 6 secured to plunger 4; a tubular core 7 coaxial with anchor 6; and an excitation coil 8 housed inside a cavity 9 on body if as shown in the drawing. Plunger 4 is normally maintained in the closed position shown in the drawing by a helical spring 13 housed inside an axial hole in anchor 6 and core 7. and located between a coupling 14, forced into a predetermined position inside core 7, and a shoulder 15 on plunger 4.

Coil 8 comprises a winding 16 embedded inside a ring of plastic material 17 conveniently having pins 18 from which project rheophores 19 connected in any appropriate manner to respective connecting elements 20. The valve is closed at the top by a skirt 21 of plastic material.

Winding 16 of coil 8 consists of a number of turns of insulated, electrically conductive wire substantially coaxial with core 7 and anchor 6. According to the present invention. said turns are arranged in parallel layers of short axial length Obu, while the number of said layers is so selected that the radial thickness nau is greater than the axial length Obn of each said layer. The ratio between the radial thickness "all of said layers and the axial length nb" of each said layer is conveniently greater than 1 but less than 4.

winding 16 produced as described above, that is, with radial thickness "a" to axial length "b" ratio greater than 1 but less than 4. has been found to provide for substantial advantages.

Firstly. it provides for a considerable reduction in response time as compared with coils having the same characteristics but the winding of which presents an "all to "bn ratio outside the above range. This is probably due to the characteristics of the magnetic flux generated by the coil through the component parts of the valve, such as body 1, anchor 6 and core 7. all of which present extensive sections due to the ample radial thickness "a" of the coil. Moreover. all other conditions remaining the same, the intensity of said magnetic flux would appear to be fairly high.

Secondly, the axial length of the valve is reduced due to the short axial length 11b11 of winding 16,, which is particularly useful for applications in which a limited amount of space is available for housing the fuel metering and atomizing valve.

To those skilled in the art it will be clear that changes may be made both to the design and arrangement of the component parts of the valve as described and illustrated herein without, however, departing from the scope of the present invention.

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Claims

1) - An electromagnetic fuel metering and atomizing valve for an internal combustion engine supply device, said valve comprising an injection nozzle in which is formed a fuel injection orifice; a plunger designed to move axially between a closed and open position wherein said orfice is respectively closed and opened; an anchor secured to said plunger a core housed in the valve body attract said anchor and designed to and an excitation coil housed in said body and comprising a number of turns of insulated, electrically conductive wire substantially coaxial with said core; characterised by the fact that said turns are arranged in parallel layers of short axial length, and the number of which is so selected that the radial thickness of said layers is greater than said axial length of each said layer.

2) - A valve as claimed in Claim 1. characterised by the fact that the ratio of said radial thickness of said layers to said axial length of each said layer is greater than 1 and less than 4.

3) - A valve as claimed in claim 1 or

2. characterised by the fact that said turns are embedded in a ring of plastic material 4) - A perfected electromagnetic fuel metering and atomizing valve for an internal combustion engine supply -i 19 k device, substantially as described and illustrated herein with reference to the accompanying drawing.

Published 1991 at The Patent Office. Concept House. Cadiff Road, Newport, Gwent NP9 I RH. Further copies may be obtained from Sales Branch, Unit 6. Nine Mile Point. Cwrnfelinfach, Cross Keys. Newport, NPI 7HZ. Printed by Multiplex techniques ltd, St Mary Cray, Kent.