GB2197386A

GB2197386A - Fuel injection nozzle

Info

Publication number: GB2197386A
Application number: GB08725049A
Authority: GB
Inventors: David John Gaskell
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1986-11-07
Filing date: 1987-10-26
Publication date: 1988-05-18
Anticipated expiration: 2007-10-26
Also published as: GB2197386B; GB8725049D0

Abstract

A nozzle body 30 has a fuel inlet recess 33 and a clamp member 34 surrounds the body and is provided with a threaded boss 36. A clamping element 39 is engaged with the boss to urge a shaped surface on a head 41 of a conduit 40 or on the clamping element (44,47, Figs. 4 to 6) into seating engagement with the recess and also to urge the clamp member into engagement with the body. <IMAGE>

Description

SPECIFICATION Fuel injection nozzle This invention relates to a fuel injection nozzle of the kind comprising an elongated body, a valve member guided for movement in the body, resilient means biasing the valve member into contact with a seating, the valve member being lifted from the seating to allow fuel flow through an outlet, by fuel under pressure supplied through an inlet.

The fuel inlet may lead directly to a chamber in which the valve member is located or it may lead into an axial passage formed in the body and which communicates with the chamber. In each case the inlet extends generally at right angles to the axis of the body and it has been the practice to form the inlet in a part secured to the body or formed integrally therewith. In the former case the part has to be secured to the body in a fuel tight manner and in the latter case the body is generally formed as a casting which is subsequently machined. In both cases the production of the body is expensive.

The object of the present invention is to provide a fuel injection nozzle of the kind specified in a simple and convenient form.

According to the invention in a nozzle of the kind specified the body is of cylindrical form and the inlet is in the form of a recess in the outer surface of the body, the nozzle including a clamp member which can be located about the body, the clamp member having a boss in which is formed a bore and a hollow clamping element engageable with said boss portion, said clamping element, when tightened in use, serving to urge a shaped surface into sealing engagement with said recess and to draw the clamp member into firm engagement with the body.

In the accompanying drawings: Figure 1 is a sectional side elevation of a known form of fuel injection nozzle illustrating a known way of providing a fuel inlet on the nozzle, Figure 2 is a sectional side elevation of part of another form of fuel injection nozzle illustrating the invention, Figure 3 is a view similar to Figure 2 showing a modification, and Figures 4, 5, 6 and 7 show further examples of the invention.

Referring to Figure 1 of the drawings the nozzle illustrated therein is known in the art as a "pencil injector" and it comprises an elongated body 10 in which is defined a bore 11.

At one end of the bore there is formed an annular seating 12 with which co-operates the shaped end of a valve member 13. The valve member is slightly smaller throughout its length than the bore 11 to provide an annular space through which fuel can flow from an inlet 14 through an outlet orifice 15 when the valve member is lifted from its seating.

The valve member is guided for axial movement within the bore by means of a bush 16 which is secured within the end of the body 10 and which has a central bore which is slightly smaller in diameter than the bore 11, the portion of the valve member extending through the bush being also slightly smaller in diameter than the remaining portion of the valve member. Located against the bush 16 is a stop plate 17 in which is formed an opening through which extends a further reduced portion 18 of the valve member and on which is mounted a spring abutment 19. The abutment 19 is engaged by one end of a coiled compression spring the opposite end of which is engaged by a further spring abutment 21.The spring abutments and the spring are located within a hollow cap member 22 which is in screw threaded engagement with complementarily internally threaded retainer member 23 which is secured to the body 10. The cap member acts to retain the stop plate 17 in position and the cap member mounts an adjustable abutment 24 whereby the force exerted by the spring 20 can be adjusted from exterior of the nozzle. The cap member also is provided with a passage 25 through which fuel collecting in the chamber occupied by the spring, can escape. In operation, when fuel under pressure is supplied through the inlet 14 the pressure acts upon the valve member to lift the valve member against the action of the spring 20 to permit fuel flow through the outlet orifice 15. The extent of movement of the valve member is limited by its abutment with the stop plate 17.

The inlet 14 in the example of Figure 1 comprises a short length of pipe 26 which is secured within a lateral bore 27 formed in a projection 28 on a close fitting annular body 29 which surrounds the body 10 The body 10 of the injector is drilled to provide an opening into the bore 11 and the body 29 together with the pipe are brazed so as to obtain a fuel tight seal. The opposite end of the short length of pipe 26 is provided with a conventional pipe connector whereby it can be coupled to a pipeline which in use extends to a fuel injection pump. It will be appreciated that the initial machining of the body 29 together with the brazing operation contributes materially to the overall cost of producing the nozzle and in addition, the brazing operation has to be carefully carried out to ensure that a fuel tight connection is obtained.

Figure 2 of the drawings illustrates in part another form of injection nozzle in which the valve member is located in a separate body which is secured to the nozzle body 30, the latter being provided with a chamber 31 to accommodate the spring which biases the valve member to the closed position. In this case the fuel is conveyed through a passage 32 formed in the body 30 from the fuel inlet to an annular space defined between the valve member and the wall of the bore in which it is located. The fuel inlet in conventional nozzles of this type has been formed in a laterally extending portion of the body 30 which portion is formed integrally with the body preferably during the casting of the body.

Figure 2 also illustrates the invention and in Figure 2 it will be seen that the inlet is in the form of a recess 33 in the body 30 and which opens into the passage 32. Also provided is a clamp member generally indicated at 34 and which comprises a body portion 35 which is provided with an integral portion 36.

The body portion 35 is provided with a central aperture 37 slightly larger in diameter than the body 30 and the boss is provided with a screw threaded bore 38 in which can be engaged a hollow clamping element in the form of a nut 39. The clamping element 39 is located about a conduit 40 which has a head 41 shaped in a manner complementary to the recess 33 and which also defines an annular ledge between which and the end of the clamping nut, is located a washer 42. In use, when the clamping element is tightened within the boss, the head 41 is urged into sealing engagement with the surface of the recess 33 to form a fuel tight seal and the body 35 is drawn against the body 30 over the region opposite to the recess 33. The conduit 40 can form the supply pipe for connection to an injection pump.

The arrangement described provides a simple and convenient method of connecting the conduit 40 in a fuel tight manner to the inlet.

The body 30 can be machined from bar stock and there is no need for a brazing operation as with the nozzle shown in Figure 1.

In the example shown in Figure 3 the boss 36A is provided with a screw thread on its outer periphery and the clamping element is in the form of a nut 39A which is engaged about the boss portion and defines a shoulder for engagement by a tubular spacer 43 which transmits the clamping force between the shoulder of the nut and the head 41 of the pipe.

In the example of Figure 4 the boss 36 is constructed as in the example of Figure 2 but the conduit is in the form of a threaded insert 44 which also serves as the clamping element. The insert has its inner end shaped to form a seal with the recess 33. A nut would be used to secure a pipe to the insert. In order to enable the insert to be tightened within the boss a portion 45 of the bore in the insert is of non-circular section to allow the engagement therewith of a complementary tool.

Figure 5 shows that the insert 44 of Figure 4 can be enlarged to accommodate an edge filter 46 or an injection control device.

Figure 6 shows that the boss 36B can be provided with a screw thread on both its exterior and interior surfaces and an insert 47 is secured within the boss. The insert 47 is shorter than the insert 44 of Figure 4 and in this case the pipe is secured by using a nut engaged with the exterior threads of the boss.

In the examples of Figures 4, 5 and 6 the clamp member once the insert has been secured in position will itseif be secured to the body. In the case where the conduit is the pipeline which conveys fuel from the pump the clamp member will not be fixed following assembly of the nozzle. It may however be fixed to the body by staking after assembly this procedure not requiring the formation of a fuel tight seal as in the known constructions.

Figure 7 shows a construction which is basically the same as the construction of Figure 6. In this case however the axis of the boss 36C is inclined to the normal to the axis of the body 30 of the nozzle.

Claims

1. A fuel injection nozzle comprising an elongated body, a valve member guided for movement in the body, resilient means biasing the valve member into contact with a seating, the valve member being lifted from the seating to allow fuel flow through an outlet by fuel under pressure supplied through an inlet, the body being of cylindrical form and the inlet being in the form of a recess on the outer surface of the body, the nozzle including a clamp member which can be located about the body, the clamp member defining a boss in which is formed a bore and a hollow clamping element engageable with said boss, said clamping element when tightened in use, serving to urge a shaped surface into sealing engagement with said recess and to draw the clamp member into firm engagement with the body.

2. A nozzle according to Claim 1 in which said surface is defined upon a head which is formed on a conduit connected in use to a fuel injection pump, said clamping element surrounding said conduit.

3. A nozzle according to Claim 2 in which said clamping element comprises a nut which is engaged with a screw thread formed in the surface of said bore.

4. A nozzle according to Claim 3 in which said clamping element is in the form of a nut engaged with a screw thread formed on the outer peripheral surface of the boss.

5. A nozzle according to Claim 1 in which said clamping element is formed by an insert which is provided with a peripheral screw thread engaged with a complementary thread formed in said bore, said insert defining said shaped surface and the insert having a central drilling through which fuel is conveyed in use to said inlet.

6. A nozzle according to Claim 5 in which said insert includes a portion extending from said bore, at least part of said portion being provided with a peripheral screw thread for engagement in use by a pipe connector.

7. A nozzle according to Claim 5 in which the axis of said insert is inclined to the normal to the axis of the body.

8. A fuel injection nozzle comprising the combinatiopn and arrangement of parts substantially as hereinbefore described with reference to the accompanying drawings.