GB2165625A

GB2165625A - Electromagnetically operable valve

Info

Publication number: GB2165625A
Application number: GB08522563A
Authority: GB
Inventors: Neil Raymond Mccrave
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1984-10-12
Filing date: 1985-09-12
Publication date: 1986-04-16
Also published as: GB2165625B; GB8522563D0; GB8425810D0

Abstract

An electromagnetically operable valve has a housing 10 in which is located a core structure 16 which defines pole pieces 17 and has windings 18. Surrounding the core structure is an armature 20 which is coupled to a valve member 13 slidable in a bore 12 in a valve housing 11. The valve member has a head 14 which is biased to an open position by a spring 34 which is located in a bore 28 in the core structure. The spring 34 at one end engages an abutment 35 carried on the stem of the valve member and at its other end against a plug 37 which is in screw thread engagement with the wall of the bore 28. The end of the plug 37 is shaped for engagement by an adjusting tool and the plug can be adjusted from the exterior of the valve once assembly has been effected. <IMAGE>

Description

SPECIFICATION Electromagnetically operable valve This invention relates to an electromagnetically operable valve for use in the fuel system of an internal combustion engine, the valve comprising an axially movable valve member shaped for co-operation with a seating, an elongated magnetic core structure having its longitudinal axis coincident with the axis of movement of the valve member, a plurality of axially spaced circumferential pole pieces defined by the stator structure, windings carried by the stator structure and which when energised cause adjacent ones of said pole pieces to assume opposite magnetic polarity, a magnetic armature surrounding the stator structure, means coupling the armature to the valve member whereby when the windings are energised, the armature will move the valve member into contact with the seating and resilient means for urging the valve member away from the seating upon de-energisation of the windings.

The object of the present invention is to provide an electromagnetically operable valve of the kind specified in a simple and convenient form.

According to the invention in a valve of the kind specified said resilient means comprises a coiled compression spring located within an axial bore in the core structure, a first spring abutment engaged with one end of the spring, said first spring abutment being mounted upon an extension of the valve member, a second spring abutment engaged with the other end of the spring, said second spring abutment being mounted on or integrally formed with an angularly adjustable plug which is in screw thread engagement with a portion of said bore, angular adjustment of the plug effecting axial movement of the second spring abutment and therefore an adjustment of the force exerted by the spring on the valve member.

Examples of electromagnetically operated valves in accordance with the invention will now be described with reference to the accompanying drawings in which the two figures are sectional side elevations of the two examples respectively.

Referring to Fig. 1 of the drawings the electromagnetically operated valve comprises a main housing 10 of hollow form within one end of which is located a valve housing 11.

Formed in the valve housing is an axial bore in which is slidably mounted a valve member 13.

At its outer end, the valve member defines a head 14 of slightly larger diameter than the bore and the end portion of the bore is shaped to form a seating into contact with which the valve head is moved to close the valve. Beneath the head the valve member is of reduced diameter to define an annular space with which communicates a passage 15 which in use is connected to the pumping chamber of a high pressure fuel injection pump for supplying fuel through an outlet connected to the pumping chamber to a fuel injection nozzle of an internal combustion engine. During inward movement of a plunger in the pumping chamber, fuel will be displaced from the pumping chamber and if the valve is open, will flow by way of the passage 15 to a drain. If on the other hand the valve is closed the displaced fuel will flow to the injection nozzle of the engine.

Located within the main housing is an elongated magnetic core structure 16 which defines a plurality of axially spaced circumferentially extending pole pieces 17, the diameters of the pole pieces decreasing towards the end of the core structure adjacent the valve member. In the grooves defined between the pole pieces are windings 18 respectively, the windings in the grooves being connected in series but the windings being so arranged that when electric current is passed therethrough adjacent pole pieces will assume opposite magnetic polarity. The core structure is integrally formed with a support portion 19 which locates in the end of the main housing remote from the valve housing.

A space is defined between the peripheral edges of the pole pieces and the internal wall of the main housing and located within this space is an axially slidable armature 20. The armature is of annular form and defines a plurality of pole faces 21 which are presented to pole faces defined by the pole pieces respectively. The armature at intervals is provided with circular apertures and at its wider end, is slidab.le on a right cylindrical internal surface of the main housing. At its other end the armature is provided with an integral right cylindrical portion 22 which is slidably mounted in an annular axially slotted bearing member 24 supported in the main housing.

The armature is located with clearance about a portion 23 of the construction which provides a return path for magnetic flux. The armature extends beyond the guide portion and terminates in an inwardly directed flange 25 the surface of which remote from the core structure is engaged by a collar 26 which is mounted about an extension 27 integral with the valve member and which extends into an axial bore 28 defined in the core structure.

The collar 26 is held in engagement with a step on the valve member by means of a retaining nut 29 secured to the extension there being located between the retaining nut and the collar, an annular elongated spacer member 30. The spacer has a flange portion 31 at its end adjacent the core structure and this forms an abutment for a first coiled compression spring 32, the other end of the compression spring bearing against an abutment member 33 which is slidable in an axial direction, about the spacer member 30. The abut ment member 33 is engageable with the opposite end face of the flange 25 remote from the collar 26.

In the open position of the valve member as shown in Fig. 1, the valve head 14 is spaced from the seating an amount which is determined by the abutment of the collar 26 with the valve housing. When the windings are energised the pole faces 21 on the armature will move towards the pole faces defined on the pole pieces 17 of the core structure and this movement will be transmitted to the valve member 13 through the spring 32. The extent of movement of the valve member is of course limited by the abutment of its head 14 with the seating. However, it is arranged once the valve member has been halted, that the armature can move a further amount until an internal step on the armature engages with a stop ring 23A carried by the core structure, such additional movement being accommodated by further compression of the spring 32.The pole faces of the armature and core structure do not engage with each other.

In order to return the valve member 13 to the open position, there is provided a further coiled compression spring 34 one end of which is supported on a spring abutment 35 mounted at the end of the extension 27 of the valve member. The other end of the spring locates against a hardened shim 36A bearing against an abutment 36 which is integrally formed with a plug 37. The plug 37 is in screw thread engagement with a thread formation formed in the bore 28 the threads having a fine pitch. The plug extends from the end of the bore remote from the valve member and a screw driver slot is provided whereby the angular setting of the plug can be adjusted. The spring 34 provides a restoring force to urge the valve member to the open position and once the windings are deenergised the spring 34 will come into play to move the valve member to the open position.

The armature will similarly be moved so that its pole faces move away from the pole faces of the core structure. Movement is imparted to the armature through the spring 32 and as previously mentioned the open position of the valve member is determined by the abutment of the collar 26 with the valve housing. It will of course be understood that angular adjustment of the plug 37 will vary the force exerted by the spring 34 on the valve member and such adjustment can be carried out when the assembly of the valve has been completed.

In view of the fact that the fuel in the passage 15 can be at an extremely high pressure, leakage of fuel will take place along the working clearance between the valve member 13 and the wall of the bore 12. This fuel will flow into the housing and apertures 38 are provided in the main housing adjacent the valve housing to allow fuel to escape. It is anticipated however that some fuel will penetrate further into the main housing and this is one reason why the armature is provided with apertures and the bearing member is slotted so that movement of the armature can take place without its movement being delayed by the development of hydraulic pressures.It will also be noted that'the plug 37 together with the abutment 36 is provided with an axially extending passage which extends from the end of the abutment adjacent the spring 34 to a port on the exterior of a reduced portion of the plug.

The core structure is held within the housing by means of a cap nut 39 which is of cupshaped form. The internal surface of the skirt portion of the cap nut is provided with screw threads which are in engagement with complementary threads formed on the periphery of the main housing. It will also be noted that interposed between the base wall of the cap nut and the core structure is the flange of an electrically insulating cap 40. The cap 40 is provided with a central aperture to allow access to the plug 37 for the purpose of adjustment and it also supports in insulated relationship, a pair of terminals in the form of contact blades 41 which are connected to the ends of the windings respectively.The contact blades are secured by tubular rivets and the central openings through the rivets are closed by solder which also secures the electrical connection to the contact blades, of the ends of the winding. The ends of the winding pass through channels 18A in the core structure, the channels being larger than the wire forming the winding to allow fuel flow. Surrounding the rivets are O-ring seal members respectively which prevent the escape of fuel along the outer peripheral surfaces of the rivets. In addition, an O-ring seal 40A is provided between the plug 37 and the central aperture in the cap 40 to prevent fuel escaping therealong. The seal 40A has the additional duty of resisting rotation of the plug 37 once the adjustment of the plug has been effected. Finally O-ring seals are located in a pair of grooves formed in the support portion 19 of the core structure, one groove 42 being formed in the face of the support portion presented to the internal wall of the main housing and the other groove 43 being disposed in the end face of the support portion presented to the cap 40.

The example shown in Fig. 2 is substantially identical with the example of Fig. 1 except for the disposition of the main sealing elements which in Fig. 1 are constituted by the seal members in the grooves 42 and 43. In the example of Fig. 2 a groove 44 is formed in the outer peripheral surface of the housing and locates an O-ring engaging with an extended portion 39A of the cap nut 39. The other groove 45 is formed in the internal surface of the skirt portion of the cap nut 39 adjacent the base wall thereof and accommodates an O-ring sealing member which engages with the peripheral surface of an insulated cap 46.

Moreover, in the example of Fig. 2, the terminals are carried by the core structure and pass through apertures in the cap 46 one such terminal being indicated at 47. Also extending through the cap 46 is a connector 48 which has a central passage in the outer end of which is mounted a restrictor 49. The inner end of the passage communicates with a space within the housing and in use a flow of fuel takes place from the interior of the housing through the restrictor 49, this flow of fuel acting to cool the winding.

Claims

1. An electromagnetically operable valve for use in the fuel system of an internal combustion engine, the valve comprising an axially movable valve member shaped for co-operation with a seating, an elongated magnetic core structure having its longitudinal axis coincident with the axis of movement of the valve member, a plurality of axially spaced circumferential pole pieces defined by the stator structure, windings carried by the stator structure and which when energised cause adjacent ones of said pole pieces to assume opposite magnetic polarity, a magnetic armature surrounding the stator structure, means coupling the armature to the valve member whereby when the windings are energised, the armature will move the valve member into contact with the seating, resilient means for urging the valve member away from the seating upon deenergisation of the windings, said resilient means comprising a coiled compression spring located within an axial bore in the core structure, a first spring abutment engaged with one end of the spring, said first spring abutment being mounted upon an extension of the valve member, a second spring abutment engaged with the other end of the spring, said second spring abutment being mounted on or integrally formed with an angularly adjustable plug which is in screw thread engagement with a portion of said bore, angular adjustment of the plug effecting axial movement of the second spring abutment and therefore an adjustment of the force exerted by the spring on the valve member.

2. A valve according to Claim 1 including a main housing of hollow form and in which said magnetic core structure is mounted, a valve housing located in one end of said main housing, said valve housing defining said seating, a cap located at the other end of the main housing, said cap defining a central aperture to allow access to said plug for adjustment purposes.

3. A valve according to Claim 2 including a cap nut engageable with the main housing to retain the cap and core structure within the housing.

4. A valve according to Claim 3 including sealing means located intermediate the cap and the plug to prevent escape of fuel therebetween.

5. A valve according to Claim 4 including a pair of terminals carried by said cap, said terminals being connected to said windings, said terminals including contact blades carried by tubular rivets secured in said cap, said tubular rivets being filled with solder, and a pair of sealing rings located about said rivets and acting to prevent escape of fuel from the interior of the main housing between said rivets and the cap.

6. A valve according to Claim 3 in which said core structure carries a pair of terminals which extend through apertures in said cap, sealing rings being provided about said terminals and acting to prevent escape of fuel from the interior of the main housing between the terminals and said cap.

7. A valve according to Claim 6 including a connector which extends through the cap and defines a restricted passage leading to the interior of the main housing whereby a flow of fuel can take place from the interior of the housing to effect cooling of said windings.

8. A valve according to Claim 3 or Claim 4 including sealing means acting to prevent escape of fuel along the interfaces of the cap and core structure and the core structure and main housing.

9. An electromagnetically operable valve comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.

10. An electromagnetically operable valve comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Fig. 2 of the accompanying drawings.

CLAIMS Amendments to the claims have been filed, and have the following effect: New or textually amended claims have been filed as follows:- Claims 9 and 10 above have been re-numbered as 12 and 13.

9. A valve according to Claim 1 in which when the valve member is in contact with the seating, pole faces defined by said pole pieces are spaced from pole faces defined by said armature.

10. A valve according to Claim 9 including stop means for limiting the movement of the armature relative to the stator structure when the windings are energised.

11. A valve according to Claim 10 including further resilient means through which the armature is coupled to the valve member, said further resilient means being stressed during continued movement of the armature after the valve member has contacted the seating and before the movement of the armature has been halted by said stop means.