GB2144177A

GB2144177A - Fuel injector

Info

Publication number: GB2144177A
Application number: GB08415517A
Authority: GB
Inventors: John Herbert Kenning; Keith Leslie Pascall; Matthew Potts
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1983-07-28
Filing date: 1984-06-18
Publication date: 1985-02-27
Also published as: GB2144177B; GB8415517D0

Abstract

A fuel injector comprises a pair of body parts 10, 11, both of cup shaped form, the skirt 26 of the part 11 being secured to the base wall 14 of the part 10. The part 11 carries a valve seat member 30 which defines an outlet orifice 31 and a disc valve member 34 is spring biased into contact with a seat rib 35 on the seat member to prevent fuel flow through the orifice. The valve member 34 is moved away from the seat rib 35 upon energisation of a solenoid 20. A pair of inlet passages 42 extend to the periphery of the injector and these are defined by slots cut in the base wall of the body part 10 before the two parts are secured together. <IMAGE>

Description

SPECIFICATION Fuel injector This invention relates to a petrol injector for supplying fuel to an air inlet manifold of an engine, the injector being of the kind comprising a hollow body, a fuel outlet orifice defined at one end of the body, a valve member formed from magnetizeable material movable in the body to control fuel flow through the outlet orifice from a fuel inlet in the body and a solenoid housed within the body, said solenoid when energised effecting movement of said valve member to permit fuel flow through the outlet orifice.

The object of the invention is to provide an injector of the kind specified in a simple and convenient form.

According to the invention in an injector of the kind specified the body is formed in two parts the first of which is of generally cup shaped form having an aperture in its base wall, the second part of the body also being of cup shaped form and having an outlet opening formed in its base wall, the skirt portion of the second part of the body being secured to the base wall of the first part of the body, a valve seat member located between said base walls, the seat member defining the outlet orifice, said valve member co-operating with the seat member to prevent fuel flow through the orifice, and a stem extending within the first part of the body into the aperture in the base wall thereof, said stem being surrounded by said solenoid winding and forming in conjunction with the base wall of the first part of the body, the poles of the solenoid, said fuel inlet being formed by a passage extending to the periphery of the body and being defined between said first and second parts of the body.

Examples of fuel injector in accordance with the invention will now be described with reference to the accompanying drawings in which.

Figure 1 is a sectional side elevation of one example of the injector, and Figure 2 is a view similar to Figure 1 showing a further example.

Referring to Figure 1 of the drawings the injector comprises a body part which is formed in two parts 10,11. The part 10 of the body is of cup shaped form having a side wall 13 and a base wall 14. The body part 10 is formed from magnetizeable material and has a groove formed in its outer peripheral surface in which is located a sealing ring 15 which in use forms a fuel tight seal with the wall of a bore formed in the inlet manifold of the associated engine.

In the base wall 14 of the body part 10 is formed an aperture 16 and extending within the aperture is a hollow stem 17 formed from magnetizeable material. The stem is provided with a collar 18 which is a snug fit within the open end of the body part 10 and is secured therein by welding.. Surrounding the stem 17 is a former 19 conveniently formed from plastics material, about which is wound a winding 20. The ends of the winding are connected to a pair of terminal posts 21 which are moulded into the former and which extend through apertures in the collar 18. The winding 20 is sealed against the fuel by a first sealing ring 22 located between the former and the base wall 14 and a second sealing ring 23 located between the former and the stem adjacent the collar.

The stem 17 extends beyond the collar and within the stem is a plug 24 which forms an abutment for one end of a coiled compression spring 25 which extends within the stem. The plug 24 is a push fit within the stem and forms a fuel tight seal with the wall thereof.

The body part 11 is also of cup shaped form but has a shorter side wall 26 than that of the body part 10. In its base wall 27 is formed a diverging outlet 28 and about a reduced portion of the base wall is located a sealing ring 29 which co-operates with the wall of the bore in the manifold in which the injector is located. The bore in the manifold intermediate the sealings rings 15 and 29 defines a fuel inlet passage connected to a source of fuel under pressure.

Located against the base wall of the body part 11 is a valve seat member 30 in which is formed an outlet orifice 31. A sealing ring 32 is located in a groove in the base wall so as to establish a fuel tight seal between the base wall and the seat member 30. Located against the inner face of the valve seat member is an annular guide member 33 which guides the movement of a disc like valve member 34 formed from magnetizeable material.

The valve member is biased towards the seat member by the aforesaid spring, the valve member being provided with a recess to locate the end of the spring. The seat member on its face presented to the valve member defines a pair of annular ribs, the inner rib 35 forms a seating for the valve member and the outer rib 36 acts to minimize the risk of the valve member tilting as it moves into contact with the seating formed by the inner rib.

The valve member is provided with a plurality of through holes 37 which lie outside the inner rib 35 and these holes in the particular example allow fuel flow from a space 38 through the outlet orifice when the valve member is lifted away from the inner rib 35.

The body part 11 is secured to the body part 10 by welding indicated at 39 and to provide accurate location of the body parts a tongue and groove connection is provided. In the example the body part 10 is provided with an annular groove 39A and the body part 11 with an annular tongue or rib 40. Moreover, before the parts are secured together a non magnetic washer 41 is positioned between the guide member 33 and the adjacent surface of the base wall 14.

Fuel is communicated to the space 38 from the exterior of the body by way of a pair or more inlet slots 42 which are formed in the base wall 14 and the fuel entering the slots is filtered by an annular filter 43 which conveniently is formed from plastics material and which is engaged about the body.

The filter has openings which are covered by a filter net.

In operation, when the winding is supplied with electric current, the base wall 14 and the stem are polarized to opposite magnetic polarity and the valve member 34 is lifted against the action of the spring 25 away from the rib 35 to permit fuel flow through the outlet orifice 31, the fuel passing through the holes 37 in the valve member. When the solenoid winding is de-energised the valve member returns into contact with the rib to halt the flow of fuel under the action of the spring, the washer 41 acting to minimize the possibility of the valve member "sticking" due to remanent magnetic flux. The guide member 33 in one example is formed from stainless steel but may be formed from a non-metallic material.

The slots 42 are radially disposed, however, they may be tangentially disposed to impart swirl to the fuel entering the space 38. In this case the holes 37 may also have their axes inclined so as not to destroy the swirling of the fuel as it enters the outlet orifice.

In the arrangement shown in Figure 2 the various parts of the injector are identical to those of the arrangement of Figure 1. The inlet slots 42 of the example of Figure 1 are however replaced by inlet slots 44 which are formed in the free end of the side wall 26 of the body part 11. The slots 44 are extended inwardly by slots 45 formed in the valve seat member 30, so that fuel can flow over the ribs 36 and 35 when the valve member is moved against the action of the spring. The holes 37 are provided in the valve member but in this case they serve to prevent damping of the movement of the valve member as displacement of the valve member takes place. The slots 44 and 45 can be tangentially disposed to impart a swirling motion to the fuel and this swirling motion can be enhanced by short ribs on the valve member or seat member intermediate the ribs 35, 36.

In both the arrangements of Figures 1 and 2 the injector may be provided with a return fuel outlet through which fuel flows the whole time the injector is in use. This return flow of fuel provides for cooling of the injector and also helps to minimize the possibility of vapour formation in the fuel. The return flow can take place through the stem 17 in which case the plug 24 is provided with a through bore.

The formation of the inlet slots in both examples is faciltated by the fact that they can be formed by a simple metal cutting operation prior to securing the two parts 10,11 of the body together.

Claims

CLAiMS

1. A petrol injector of the kind specified in which the body is formed in two parts the first of which is of generally cup shaped form having an aperture in its base wall, the second part of the body also being of cup shaped form and having an outlet opening formed in its base wall, the skirt portion of the second part of the body being secured to the base wall of the first part of the body, a valve seat member located between said base walls, the seat member defining the outlet orifice, said valve member co-operating with the seat member to prevent fuel flow through the orifice, and a stem extending within the first part of the body into the aperture in the base wall thereof, said stem being surrounded by said solenoid winding and forming in conjunction with the base wall of the first part of the body, the poles of the solenoid, said fuel inlet being formed by a passage extending to the periphery of the body and being defined between said first and second parts of the body.

2. An injector according to Claim 1 in which said passage is defined by a siot formed in the surface of one of said body parts presented to the other body part.

3. An injector according to Claim 2 in which said slots are tangentially disposed relative to the outlet orifice so as to cause swirl of the fuel entering said orifice.

4. An injector according to Claim 3 in which said body parts define a tongue and groove connection to provide accurate location of the parts.

5. A petrol injector comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Figure 1 of the accompanying drawings.

6. A petrol injector comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Figure 2 of the accompanying drawings.