GB2201751A

GB2201751A - Solenoid valve

Info

Publication number: GB2201751A
Application number: GB08800283A
Authority: GB
Inventors: Nobukazu Takagi; Keiichi Yamada
Original assignee: Diesel Kiki Co Ltd
Current assignee: Bosch Corp
Priority date: 1987-01-23
Filing date: 1988-01-07
Publication date: 1988-09-07
Anticipated expiration: 2008-01-07
Also published as: GB8800283D0; JPS63115676U; GB2201751B; KR920006592Y1; KR880015165U; JPH0426772Y2; DE3801304A1

Description

1 SOLENOID VALVE 1 1 ?1 t ., 4, - 17p; 1 The present invention relates

generally to solenoid valves for use in fuel injection devices, for example, for opening and closing fuel passages, and more particularly to a solenoid valve having a mechanism for detecting valve-opening and closing signals.

Solenoid valves of this type are known in which an excitation coil on a stator is energized to pull an armature whereupon a needle valve element secured to the armature is displaced to open or close a fuel passage defined between itself and a mating valve seat. The needle valve element and the valve seat jointly form an electric switch for detecting the position of the needle valve element.

An example of such known solenoid valves is disclosed in Japanese Patent Laid-open Publication No. 60-129483. The disclosed valve includes a needle valve element coated on its periphery with an insulating layer for electrically separating or insulating a slidably contacting portion of the needle valve element from a guide hole in the valve body in which the needle valve element is slidably received. The needle valve element is biassed by a valve spring through which valve-opening and closing signals are 2 delivered from the electric switch to the outside of the solenoid vlave.

The solenoid valve of the foregoing construction has a drawback that since a stator and an armature are spaced from one another by a relatively small gap and the armature is normally held in conduction relative to the valve body, a certain amount of dust in the gap might make a connection between the armature and the stator, leading to accidental generation of a valve-opening or closing signal from the electric switch.

iculty in view, it is the With the foregoing diff principal object of the present invention to provide a solenoid valve incorporating an electric switch which is simple in construction and capable of producing valve-opening and closing signals stably and accurately.

Another object of the present invention is to provide a solenoid valve having a great flexibility for the connection of output leads of an electric switch.

According to the present invention, the foregoing and other objects are attained by a solenoid valve comprising: a stator having at least one excitation coil; an armature confronting to the stator and connected with a needle valve element; a valve spring urging the armature in a direction away from the stator; a valve body having a guide hole for slidably receiving therein the needle valve element and a valve seat against which the needle valve element is A Cl A k 1 - 3 seated; an electric switch jointly formed by and between the needle valve element and the valve seat; the valve body being composed of a first body member and a second body member, the first body member having said guide hole, the second body member including the valve seat and containing the first body member; and the needle valve element being electrically insulated from the second body member excepting when the needle valve element is held in contact with the valve seat.

The armature is electrically connected with the stator through the needle valve element and the valve spring and hence is normally held in the same electrical potential state as the stator. On the other hand, the valve body, which has the valve seat against which the needle valve element is seated, is normally electrically insulated from the stator. With this construction, the output signals from the electric switch are produced depending on conduction and non-conduction of the needle valve element and the valve seat and hence they are free from any influence of dust which may be present in a gap between the armature and the stator.

Many other advantages and features of the present invention will become manifest to those versed in the art upon making reference to the detailed description and the accompanying sheets of drawings in which a preferred structural embodiment incorporating the principles of the present invention is shown by way of illustrative example.

- 4 The drawing is a vertical cross-sectional view of a solenoid valve embodying the present invention.

As shown in the drawing, a solenoid valve embodying the invention is suitable for use in a fuel injection device (not shown) and includes a generally cup-shaped housing 1 firmly fitted around the outer periphery of a circular disk-like stator 2, and an armature 3 disposed between the housing 1 and the stator 2 in confronting relation to the stator 2.

The stator 2 has a plurality (four in the illustrated embodiment) of annular coil-receiving grooves 5a - 5d defined in an upper surfacethereof in concentric relation about a central through-hole 4 for receiving respectively therein excitation coils 6a - 6d. The excitation coils 6a - 6d are wound such that the direction of winding of adjacent excitation coils are opposite to one another. Thus adjacent excitation coils receive exciting currents flowing therethrough in opposite directions, thereby generating a plurality of lines of magnetic flux flowing between the stator 2 and the armature 3 in different directions. With this arrangement, leakage of magnetic flux is substantially negligible and a highly efficient magnetic circuit is produced between the stator 2 and the armature 3.

The armature 3 is composed of a ring-shaped disk of a 1 k 1 - 5 magnetic material and faces the upper surface of the stator 2. The armature 3 has a central hole through which an upper portion of a needle valve element 7 extends. The needle valve element 7 is fastened by a nut 9 to the armature 3 with a washer or spacer 8 disposed between the nut 9 and the armature 3. The armature 3 includes an outer peripheral edge bent in a direction away from the stator 2 so as to increase the mechanical strength of the armature 3.

The stator 2 includes an insulating layer 10 of fluorocarbon resin coated over a lower surface thereof. An inverted hat-shaped valve body 11 is disposed on the stator 2 with the insulating layer 10 disposed between the stator 3 and an annular flange of the valve body 11 and is secured to the stator 2 by a plurality of screws 13 (only one shown) extending through bushes or washers 12 of insulating material disposed between the stator 2 and the valve body 11. Thus, the stator 2 and the valve body 11 are electrically separated or insulated from one another.

The valve body 11 has a central guide hole 14 in which the needle valve element 7 is slidably received.

valve body 11 includes a downwardly converging valve seat complementary in shape to a tapered lower end of the needle valve element 7 for sealing contact with the valve element 7 to selectively block fluid communication between a fluid inflow passage 16a and a fluid outflow passage l6b defined in the valve body 11.

The valve body 11 is composed ofafirst body member 17 including the guide hole 14 stated above, and a second body member 18. The member 17 is in the shape of a hollow cylinder having an outside diameter slightly smaller than the diameter of a mounting bore 19 defined in the second body member 18. The hollow cylindrical first body member 17 is firmly retained in the mounting bore 19 by means of a curable adhesive solvent 21 filled in a gap 20 between the first and second body members 17, 18. The outer periphery of the first body member 17 and the periphral wall of the mounting bore 19 have a confronting pair of laterally spaced V-shaped grooves 22, respectively, so that upon solidification of the adhesive solvent 21, the first body member 17 is firmly retained in position against removal. The first body member 17 has steps 23a, 23b on opposite ends thereof for receiving therein O-rings 24 to provide a hermetic seal, thereby preventing a valve-working fluid (fuel in the fuel inj ection device) from leaking through the gap 20 toward the stator 2. The housing 1, a first spring retai.ner 26, a second spring retainer 30,and a valve spring 31 are made of electrically conductive material so that the needle vlave element 7 and the stator 2 are always held in the same state in respect of electrical potential, via those 25 component parts 26, 30, 31 stated above. When the needle valve element 7 is separated from the valve seat 15, the needle valve element 7 and the valve body 11 or the stator I k - 7 2 and the valve bocly 11 are held in i)on-conduction or insulated from one another. When the needle valve element 7 is seated against the valve seat 15, the valve body 11 is electrically connected with the stator 2 through the needle 1 valve element 7. Consequently, the needle valve element 7 and the valve seat 15 jointly form an electric switch 32. On-off output signals of the switch 32 are delivered to the outside of the solenoid valve through a pair of output leads 33 connected respectively to terminals (not shown) disposed at any suitable positions on the housing 1 and the valve body 11, thus enabling detection of closing and opening of the fuel inflow and outflow passages 16a, l6b.

The first spring retainer 26 has a lower portion f itted in a central hole 25 in the housing 1 to join the spring retainer 26 to the housing 1. The upper portion of the first spring retianer 26,projecting upwardly from the housing 1 is covered by a cup-shaped cover 27 fitted around the outer periphery of the projected upper portion.

The cover 27 receives therein a rod 28 extending integrally upwardly from the needle valve element 7. The rod 28 retains thereon a snap ring 29 against which the second spring retainer 30 is seated. The valve spring 31 is in the form of a compression coil spring and is disposed between the first spring retiner 26 and the second spring retainer 30.

The lower end face of the first spring retainer 26 is engageable with an upper peripheral edge of the spacer 8 to k 1 - 8 limit upward movement of the armature 3.

The solenoid valve of the foregoing construction operates as follows: When the excitation coils 6a - 6d are energized to complete the magnetic circuit between the stator 2 and the armature 3, the stator 2 is magnetized to pull the the armature 3. This movement of the armature 3 causes the needle valve element 7 to be displaced downwardly against the force of the valve spring 31 until the tapered lower end of the needle valve element 7 is seated against the valve seat 15, thereby blocking fluid communication between the fluid inflow passage 10a and the fluid outflow passage l6b. In this instance, the electric switch 32 is turned on.

When supply of exciting current to the excitation coils 6a - 6d is terminated to de-energize the latter, the armature 3 and the needle valve element 7 connected thereto are moved upwardly by the force of the valve spring 31 until the spacer 8 engages the lower end face of the first spring retainer 26. Thus the tapered lower end of the needle valve element 7 is separated from the valve seat 15, thereby making flow communication between the fluid inflow passage 16a and the fluid outflow passage l6b. In this instance, the electric switch 32 is turned off.

One of the output leads 33 connected to the non-illustrated terminal on the housing 1 may be replaced with a lead connected to the screw 13.

As a further alternative, the insulating layer 10 may 1 -1 k - 9 be formed of an insulative materal ion-plated over the stator 2.

Obvigusly, many modifications and variations of the present invention are possible in the light of the above teaching. It is therefore to be understood that,within the scope of the appended claims, the invention may be practised otherwise than as specifically described.

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Claims

CLAIMS:

1. A solenoid. valve comprising:

(a) a stator having at least one excitation coil; (b) an armature confronting to said stator and connected with a needle valve element; (c) a valve spring urging said armature in a direction away from said stator; (d) a valve body having a guide hole for slidably receiving therein said needle valve element and a valve seat against which said needle valve element is seated; (e) an electric switch jointly formed by and between said needle valve element and said valve seat; (f) said valve body being composed of a first body member and a second body member, said first body member having said guide hole, said second body member including said valve seat and containing said first body member; and (g) said needle valve element being electrically insulated from said second body meinber excepting when said needle valve element is held in contact with said valve seat.

2. A solenoid valve according to claim 1, said stator being in the shape of a circular disk and having a central through-hole and a surface confronting said armature, said surf ace having def ined therein one or more annular coil-receiving grooves disposed concentrically around said central through-hole.

3. A solenoid valve according to claim 2, the number 11 of said excitation coilsbeing plural, adjacent excitation coils being wound in opposite directions so that exciting current flow through said adjacent excitation coils in opposite.directions.

4. A solenoid valve according to any preceding claim, the needle valve element extending perpendicular to a surface of said armature facing said statorand extending through said through-hole in said stator.

5. A solenoid valve according to any preceding claim, the I needle valve body being disposed on one of the opposite surfaces of said stator, said excitation coil(s) being disposed in the other surface of said stator.

6. A solenoid valve according to any preceding claim the armature being in the form of a circular disk and having an outer peripheral edge bent in a direction away from said stator.

7. A solenoid valve according to any preceding claim, said first and second body membersbeing spaced by a gap, said gap being filled with a curable adhesive solvent.

8. A solenoid valve according to claim 5, said valve body and said stator being separated from one another by an insulating layer.

9. A solenid valve according to any preceding claim, the valve body having a fluid inflow passage and a fluid outflow passage communicatable with each other when said needle valve element is seated against said valve seat.

10. A solenoid valve according to any preceding claims, the 1 - 12 first body member being formed of an electrically insulative material.

11. A solenoid valve substantially as described with reference to, and as shown in, the accompanying drawing.

Published 1988 at The Patent Office, State House, 68171 HoIborn, London WC1R 4TP. Further copies may be obtained from The Patent Offtw,