GB2183293A

GB2183293A - Multi-cylinder fuel injection internal combustion engine

Info

Publication number: GB2183293A
Application number: GB08627524A
Authority: GB
Inventors: Gunter Kampichler
Original assignee: Motorenfabrik Hatz GmbH and Co KG
Current assignee: Motorenfabrik Hatz GmbH and Co KG
Priority date: 1985-11-23
Filing date: 1986-11-18
Publication date: 1987-06-03
Also published as: FR2593557A2; JPS62129564A; IT8622126A0; IT1197517B; DE3541497A1; GB8627524D0

Abstract

The respective valve 392 in each of a plurality of injectors fed by a common plunger fuel injection pump, which determines the timing of fuel supply to the injector needle valve 380, is operated by cylinder compression pressure acting through injector duct sections 368r, 372r, 374 and 376r and cylinder head duct sections 20r and 20rr. The duct section 368r extends to the end of the injector body 368 remote from the combustion chamber 10aa and is closed by the end 414a of a screw 414 which may be removed to clean carbon deposits from the compression pressure duct. <IMAGE>

Description

SPECIFICATION Multi-cylinder Fuel Injection Internal Combustion Engine The invention relates to a multi-cylinder fuel injection internal combustion engine in which a common injection pump is provided and a closure member is co-ordinated with each injector. An example of such an engine is described in the specification of co-pending U.K. application No.

8505876.

With injection installations of this kind, there is the disadvantage that after a rather extensive period of operation the connecting bore, or at least the region of it adjacent the cylinder, gradually becomes blocked with combustion residues (coked up) and thus its free cross-section is reduced and the control function of the piston is altered disadvantageously.

It is the object of the present invention to overcome this disadvantage by providing a simple but yet effective possibility for cleaning the connecting bore.

The invention therefore provides a multi-cylinder fuel injection internal combustion engine in which a common injection pump is provided and a closure member is co-ordinated with each injector, which maintains the pressure pipe to the injection opening closed and opens it only in dependence upon the pressure in the associated cylinder, which determines the moment of injection, wherein the closure member is formed as a piston and the duct connecting the working space of the piston and the working space of the cylinder is formed by a connecting bore in the housing of the injector and wherein the connecting bore, at its end remote from the working space of the cylinder, opens out of the component of the housing which contains it and is closed, in the operating condition of the engine, by a sealing member.

When necessary, therefore, with the injector installed, the sealing member can be removed and the connecting bore can be blown through using the compression pressure itseif, when the engine is running, or if the engine is inoperative it can be penetrated and thus cleaned throughout its whole length by a suitable tool (pliable wire or the like).

Penetration of the connecting duct can also be achieved if the injector is removed.

In an example of the invention, it is advantageous to form the sealing member as a screw with a conical sealing element for closing the end of the connecting bore.

Cleaning of the connecting bore in each condition of the injector is thus made possible in that the screw is located on the housing of the injector in such a way that it is accessible in the demounted position as well as in the installed position of this injector.

Cleaning of the connecting bore by blowing through or penetration is made significantly easier according to a preferred sample, if the bore, which opens into the working space of the cylinder and surrounds the end part of the injector in the machine housing (cylinder head), is provided over its whole length with a side extension which extends at least approximately parallel to the axis of the connecting bore.

There will now be described an example of an engine according to the invention.

It will be understood that which is to be read with reference to the drawings, is given by way of example only and not by way of limitation.

In the drawings: Figure 1 shows the injector in its installed position and in longitudinal section taken on the line A-A of Figure 3; Figure 2 shows the injector and its securing means partly in longitudinal section taken on the line B-B of Figure 3; Figure 3 is a plan view of the injector of Figure 1; and Figure 4 is a detail of Figure 1 in cross-section taken on the line C-C thereof.

As described in the above mentioned patent specification, the individual components 368, 372, 374 of the injector are firmly clamped together by means of the screw-threaded casing 376 and are held in their required mutual angular relationship by means not shown, for example, securing pins. In its installed position, the injector is located with the lower face of the part 376 on the spacing ring 382 which rests in turn on the seating 20s of the cylinder head 20a. Thus, the component 374 containing the injection openings 374a projects through a bore 20r into the working space 1 Oaa of the associated cylinder 10a in which the piston 78 is received.

In order to secure the injector in the cylinder head 20a, two screw-threaded holes 20g (Figure 2) are formed in the latter, each of which received a securely screwed in stud 400, which is also provided at its free end 400a with a screw thread. The two bores 402a of a flange-shaped strap 402 are pushed onto the two studs 400 in such a way that the strap receives in its central bore 402b a stepped cylindrical securing member 404 and thus rests with its dome-shaped under-surface 402c on a shoulder 404a of the securing member 404. A pressure pipe 406 is located in a recess 368q formed in the upper face of the component 368 and in a recess 404q formed in the lower face of the component 404. (in Figure 2 the pipe 406 is shown in the plane of the studs 400 in order to provide greater clarity. Its exact position is, however, shown in Figure 3).As soon as the nuts 408 screwed onto the studs 400a are tightened, the securing member 402 presses against the component 404 and on the one hand the pressure pipe 406 is firmly clamped between the components 404 and 368 and on the other hand the whole injector is pressed against the sealing ring 382 and against the seating 20s in the cylinder head 20a.

The pressure pipe 406, by which the fuel is delivered from a storage container by an injection pump described in said patent specification but not shown here, is provided with a cross bore 406a-as clearly shown in Figure which communicates with a bore 368a in the component 368 through a sealing ring 409. A cross bore 368b leads to the longitudinal bore 368c in the component 368, which opens in turn into a bore 372a in the component 372.

This bore is in communication with the longitudinal bore 374b of the component 374, which in turn opens into the recesses 374c and 374d. From here the fuel gains access to the injection openings 374a at the end of the injector. These injection openings are opened and closed by the end 380a of a jet control needle 380 which is actuated against the spring 388 by means of the pressure of the fuel on its shoulder 380c.

The cross bore 368b is tightly closed at its free end by a ball 384 just as also the upper end of the bore 368c is likewise sealingly blocked by a ball 386. In the axial centre of the part 368 is slidably mounted a control piston 382 actuated by the compression pressure in the associated working space 1 Oaa and which has a recessed part 392a in its central region.

The control piston 392 is pressed against a fixed upper abutment 396 under the influence of a spring 394. The spring 394 is supported on a fixed spring plate 390. The upper end 390a of the spring plate 390 serves at the same time as an abutment for the control piston 392 in its lower position. The combustion pressure from the working space 1 Oaa is transmitted to the working space 368e through the bores 368rr, 368r, 372r, 374r and through the annular space 376r and 20r.

A return bore 404d is formed in the securing member 404 at whose screw-threaded outlet 404g a nipple 410 is connected to the return pipe 41a and 410b. The return bore 368cc in the component 368, which on the one hand opens into the bore 404d through a sealing ring 412 and on the other hand opens into the internal space 368 and carries the leakage fuel which accumulates within the injector and conveys it into the return pipe 410, 410a, 410b.

Several injectors are connected to the pressure pipe 406 in the same way. In each injector the connecting duct to the injection openings 374a is maintained closed by the associated control piston 392, as shown in Figure 1. However, as soon as the pressure in the associated cylinder working space 10aa reaches the necessary level for the commencement of the injection process, then this combustion pressure, acting on the upper face of the control piston 392 in its working space 368e, moves the control piston 392 out of the position shown in Figure 1 in which it obstructs the bore 368b to a position shown in Figure 2, in which it opens the bore 368b.Only in the position shown in Figure 2 can the fuel from the pressure pipe 406 gain access to the injection openings 374a of the injector to be injected into the working space lOaa of the cylinder. As soon as the pressure in the working space 368e declines, the return spring 390 moves the control piston 392 back again into the obstructing position shown in Figure 1.

It is clearthat in the ducts extending within the injector, which carry the compression pressure to the working space 368e, gradually, after a rather extensive period of operation, combustion residues from the associated working space 10aa settle and bring about an alteration of the free cross-section here due to coking-up, whereby the control function of the control piston 392 can be disadvantageously influenced. To avoid this disadvantage, according to the invention, a possibility for cleaning out is provided. This consists in that the bore 368r is led up to the upper end of the component 368 and is closed, during the operation of the engine by a closure screw 414 with a conical sealing element 41 4a (Figure 1). The screw 414 passes through the part 404 and is screwed in the component 368.In addition, the bore 20r in the cylinder head 20a is provided with a side extension 20rr, which extends co-axially or substantially co-axially to the bore 374r in the component 374.

In this way, it is possible to open the closure screw 414with the engine running and by means of the compression pressure itself to blow through the connecting ducts 20rr, 376r, 374, 372r, 368r and thus clean them. It is however, possible to penetrate these connecting ducts and clean them by means of a suitable tool (pliable wire or the like). The coking residues then fall into the working space 1 Oaa of the cylinder 10a and will be eliminated by the next combustion.

Of course, it is possible to remove the whole injector and only then to clean the connecting ducts mentioned after removal of the closure screw 414.

A possibility of cleaning the inclined bore 368rr which leads to the working space 368e is not provided in the present example since experience shows that coking arises to the greatest degree in the ducts closely adjacent the cylinder working space 1 Oaa. However, if it should be necessary to clean the inclined bore 368rr, which is at some distance from the working space 1 Oaa, this inclined bore can be continued to the periphery of the component 368 and this region can be closed off by a closure screw removed only for cleaning purposes.

Claims

1. A multi-cylinder fuel injection internal combustion engine in which a common injection pump is provided and a closure member is coordinated with each injector, which maintains the pressure pipe to the injection opening closed and opens it only in dependence upon the pressure in the associated cylinder, which determines the moment of injection, wherein the closure member is formed as a piston and the duct connecting the working space of the piston and the working space of the cylinder is formed by a connecting bore in the housing of the injector, and wherein the connecting bore, at its end remote from the working space of the cylinder, opens out of the component of the housing which contains it and is closed, in the operating condition of the engine, by a sealing member.

2. An internal combustion engine according to claim 1, wherein the sealing member is formed as a screw with a conical sealing element which closes the end of the connecting bore.

3. An internal combustion engine according to claim 2, wherein the screw is located on the housing of the injector in such a way that it is accessible in the demounted position as well as in the installed position of the latter.

4. An internal combustion engine according to claim 1, wherein in the engine housing (cylinder head) which opens into the working space of the cylinder and surrounds the end part of the injector is provided over its whole length with a side extension which extends at least approximately parallel to the axis of the connecting bore.

5. A multi-cylinder fuel injection internal combustion engine constructed and arranged substantially as hereinbefore described with reference to and as shown in the drawings.