GB2145469A - I.C. engine fuel injector assembly - Google Patents

Abstract

A body 10 which mounts a fuel injection nozzle defines a step 12 against which an annular member 13 can bear to provide a clamping force at sealing faces of the nozzle and the engine. The body defines a flange 17 in which are formed a plurality of slots 18 and the member 13 has ribs 19 complementary to the slots whereby the member can be passed over the flange and then moved angularly to cause the ribs 19 to engage the flange thereby to allow an extraction force applied to the member to be transmitted to the body. <IMAGE>

Description

SPECIFICATION Fuel injector assemblies This invention relates to fuel injector assemblies for use with internal combustion engines, the assemblies being of the kind which comprises a cylindrical body having a fuel injection nozzle mounted at one end, the nozzle and at least part of the body being mounted in use, in a bore defined in the cylinder head of an engine, the bore opening into a combustion chamber of the engine.

Such an assembly usually has a step defined on the nozzle or on a part securing the nozzle to the body which step in use, engages with a sealing washer disposed adjacent a step in the bore, to form a gas-tight seal. The clearance between the nozzle body and the portion of the bore lying between the combustion chamber and the step is as small as possible since the volume of the clearance does represent part of the unswept volume of the associated cylinder. In use however combustion gases enter the clearance and carbon deposit can form making it difficult to remove the assembly.

It is known to form integral lugs on the assembly which lugs are normally used as a means of clamping the assembly in position on the engine. The lugs can also be utilised to apply an extraction force to the assembly to facilitate removal of the assembly from the bore. It is not always convenient to form the lugs as integral parts of the cylindrical body and it is known to form a step on the body for engagement by a ring member which is provided with lugs. In this case however since the ring member simply locates about the body, it cannot be used to assist in the extraction of the assembly from the bore.

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

According to the invention a fuel injector assembly of the kind specified comprises an annular member for engagement against a step defined on said body, said member defining means whereby the member in use can be secured to the structure of the engine so as to apply a clamping force against said step, and interengageable means on said member and said body whereby when the member is in engagement with said step the member and body can be moved angularly relative to each other to secure the member against detachment from the body.

In the accompanying drawings: Figure 1 is a perspective view showing a portion of a fuel injector assembly in accordance with the invention.

Figure 2 is a part sectional side elevation of a portion of the assembly of Fig. 1 shown in position on the cylinder head of an engine.

Figure 3 is a sectional side elevation of another example of the ring member which forms part of the assembly, and Figure 4 is an underside view of the member shown in Fig. 3.

Referring to Figs. 1 and 2 of the drawings the injector assembly includes a body 10 of cylindrical form which in known manner, is adapted to be mounted within a stepped bore formed in the cylinder head 11 of the associated engine. The bore extends into a combustion space of the engine and the body mounts a fuel injection nozzle (not shown) the nozzle conveniently being secured to the body by means of a cap nut. The injector assembly must be clamped into the aforesaid bore in order to establish a gas-tight seal between a step in the bore and an end surface of the nozzle or cap nut.

The nozzle body 10 is formed with a step 1 2 against which locates an annular member 1 3 which is provided with lug portions 14 in which are defined through holes 1 5 respectively for the reception of bolts 1 6 whereby the member can be secured to the cylinder head 11 and at the same time engage the step 1 2 to provide a clamping force. Conveniently the underside of the member 1 3 is shaped as shown in Fig. 2, so that line contact only is established with the step 1 2.

This permits the bolts 1 6 to be tighted to different amounts without affecting the clamping force or imposing any side thrust on the body 10.

In order to permit the lugs to be used to assist withdrawal of the body and nozzle from the aforesaid bore, a glange 1 7 is formed on the end of the body 10 the flange 1 7 in the particular example, being of substantially the same diameter as the main portion of the body.

The aforesaid flange and the aperture in the member 1 3 are specially shaped to provide interengageable means whereby when the member 1 3 has been engaged with the step 12, the member and body can be moved angularly relative to each other to prevent detachment of the member from the body.In the particular example, the flange 1 7 is provided with four equiangularly spaced slots 1 8 which are complementary to ribs 1 9 formed on the internal wall of the aperture in the member 1 3. In order to assemble the member 1 3 to the member 10 it is necessary to adjust the relative position of the member and the body so that the ribs 1 9 can pass along the slots 1 8 to permit engagement of the lower surface of the member with the step 1 2. The clamping bolts can then be tightened to clamp the member in position.When it is required to impart axial thrust to the body 10 in order to withdraw the body from the bore, the bolts can be removed and the member moved angularly so that the end faces of the ribs engage with the whole portions of the flange 1 7. Means can then be secured to the member to prove the desired axial thrust.

Alternatively when assembling the member 1 3 to the body 10 the member and body are moved angularly after engagement of the member with the step 1 2, to a position such that the ends of the ribs engage the whole portions of the flange. The bolts 1 6 are then secured in position and as shown in Fig. 2, the bolts may be provided with circlips 20 which as the bolts are unscrewed, engage with the lugs to impart to the body 10 the desired axial thrust to achieve extraction of the body from the bore. The ribs 1 9 of the member 1 3 may be formed by a broaching operation.

An alternative form of the annular member is seen in Figs. 3 and 4. The member 21 is of substantially the same shape as the member 1 3 but the aperture therein is constructed in a different fashion. A drilling of the same diameter as the reduced portion of the body 10 lying between the step 1 2 and the flange 1 7 is first made in the member 21 and then intermediate the ends of the drilling a groove 22 is formed which is of a diameter so that it can accommodate the flange 1 7. Finally the wall of the drilling which lies between the groove 22 and the lower surface of the body is machined using a milling cutter of a substantially smaller diameter than the diameter of the drilling. The cutter indicated in outline at 23 in Fig. 4, provides four recesses in the wall of the drilling leaving four ears 24 which are the equivalent of the ribs 1 9. The grooves 1 8 in the flange 1 7 on the body 10 may be of complementary shape to the ears 24 to permit assembly of the member to the body.

Claims (5)

1. A fuel injector assembly for use with an internal combustion engine, the assembly comprising a cylindrical body having a fuel injection nozzle mountred at one end, at least part of the body being mounted in use in a bore defined in the cylinder head of an engine, the bore opening into a combustion chamber of the engine, the assembly further comprising an annular member for engagement against a step defined on said body, said member defining means whereby the member in use can be secured to the structure of the engine so as to apply a clamping force against said step, and interengageable means on said member and said body whereby when the member is in engagement with said step the member and body can be moved angularly relative to each other to secure the member against detachment from the body.

2. An assembly according to Claim 1 in which said interengageable means comprises a flange defined on the body, a plurality of slots formed in the flange and a plurality of ribs defined on the internal surface of said member whereby the member can be passed over said flange to engage with the step and then moved angularly relative to the body to allow said ribs to engage with the flange.

3. An assembly according to Claim 1 or Claim 2 in which said member is provided with ears defining apertures for the reception of bolts whereby the member can be secured to the cylinder head of he engine.

4. An assembly according to Claim 3 in which said bolts are provided with circlips for engagement with the lugs when unscrewing said bolts from the cylinder head.

5. A fuel injector assembly substantially as hereinbefore described with reference to the accompanying drawings.