GB2322411A

GB2322411A - I.c. engine fuel-injection valve with additional supply line eg for water

Info

Publication number: GB2322411A
Application number: GB9802025A
Authority: GB
Inventors: Karl Hofmann
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1997-02-20
Filing date: 1998-02-02
Publication date: 1998-08-26
Anticipated expiration: 2018-02-02
Also published as: JPH10246166A; FR2759738B1; GB9802025D0; GB2322411B; FR2759738A1; DE19706661A1

Abstract

The valve has a valve member 9 with an opening pressure shoulder 15 which protrudes into an enlarged pressure chamber 17 into which the fuel supply duct 19 issues. The valve has a second supply line 39, eg for water, which extends completely inside the valve body 3 and issues either also into the pressure chamber 17, as in fig.2, or into the annular duct 23 below the pressure chamber 17, as in fig.10. An apertured sleeve (47, fig.3) may be provided in the annular duct 23 to produce a desired emulsion of fuel and water. The shaft of the valve member 9 may have longitudinal grooves (57, fig.4) to keep fuel and water separate or the shaft may have a square (figs.5-7) or toothed (figs. 8,9) cross-section. The injector is simple to manufacture, has no thin walls so can operate with pressures up to 1800 bar and can be incorporated into current engines without structural modifications.

Description

1 2322411

DESCRIPTION FUEL-INJECTION VALVE FOR INTERNAL COMBUSTION ENGINES

The invention relates to fuel-injection valves for internal combustion engines.

Fuel-injection valves are already known which have a valve member which is guided in an axially displaceable manner in a bore of a valve body and which comprises on its combustion chamber-side end a valve sealing surface, with which, for the purpose of controlling an injection crosssection, the said valve member cooperates with a housing-fixed valve seat surface, and having a pressure shoulder, which acts in the opening direction of the valve member, on the shaft of the valve member, which pressure shoulder protrudes into an enlarged cross-section pressure chamber, into which, furthermore, issues a pressure duct which can be connected to a high pressure fuel source, wherein the pressure chamber is connected to the valve seat surface by way of an axially extending annular duct formed between the valve member shaft and the wall of the bore, and having a second supply line in the valve body, by way of which second supply line a second medium is supplied to the injection cross- section of the injection valve.

In the case of this type of fuel-injection valve for internal combustion engines which is known from DE 39 28 611 Al, a mixture or emulsion of diesel fuel and water is injected into the internal combustion engine in order to achieve a combustion which is optimised with respect to pollutant emissions. To this end, the known fuel-injection valve comprises a piston-shaped valve member which is guided in an axially displaceable manner in a bore of a valve 2 body and comprises on its combustion chamber-side end a valve sealing surface, with which, for the purpose of controlling an injection cross- section or an injection bore, the said valve member cooperates with a valve seat surface on the valve body. The valve member comprises on its shaft a pressure shoulder which acts in the opening direction and with which said valve member protrudes into an enlarged cross-section pressure chamber into which, furthermore, issues a pressure duct which can be connected to a fuel-injection pump. The pressure duct is connected to the injection cros-section by way of an axially extending annular duct formed between the valve member and the bore. In order to supply the second medium, in particular water, the known fuel-injection valve is provided with a second supply line which initially penetrates the valve body in an axial manner and then issues into an annular chamber which is formed between the valve body and a tensioning nut. From this site the water passes by way of an annular cross-section formed between the valve body and the tensioning nut to the end, in proximity to the valve seat, of the annular duct between the valve member and the valve bore and at this site issues into the valve body by way of radial bores therein.

However, the known fuel-injection valve has the disadvantage that it has a complicated structure by virtue of the provision of the water supply duct between a tensioning nut and the valve body and can only be produced with a large amount of manufacturing outlay. Moreover, owing to the low remaining wall thicknesseson the shaft of the valve body, the known fuelinjection valve is not suitable for high injection pressures up to 1800 bar. The supply of the water in the region in proximity to the valve seat represents a further 3 disadvantage, whereby it is not possible to achieve a favourable fuel- water emulsion.

In accordance with the present invention, the second supply line extends completely in the valve body and issues directly into the pressure chamber, or at least in proximity to the pressure chamber, into a chamber which is defined between the valve member and the wall of the bore.

In contrast to the abovedescribed known arrangement, a fuel-injection valve for internal combustion engines in accordance with the invention has the advantage that in order to supply the second medium, in particular water, it is not necessary, in contrast to conventional fuel- injection valves, to provide an additional component for the purpose of achieving high fuel-injection pressures. Thus, the fuel-injection valves, in accordance with the invention, for the purpose of injecting fuel and water can be incorporated, without any additional structural modifications, into current internal combustion engines. This is achieved in an advantageous manner by virtue of the fact that the second supply line for the water is completely integrated into the valve holding body and only extends therein. In so doing, the second supply line issues in an advantageous manner directly into the pressure chamber of the fuel- injection valve or at least in proximity to the pressure chamber into the bore which guides the valve member. In this manner the original wall thickness of the valve body is maintained, so that, furthermore, the fuellwater-injection valve is suitable'for fuel-injection pressures of up to 1800 bar.

Since the supplied fuel quantities and pressures are greater than the supplied water quantities, the through-flow cross-section of the fuel supply line 4 is formed in an advantageous manner to be larger than the through-flow crosssection of the water supply line. In order to guarantee that in the region in proximity to the valve seat pure fuel is stored upstream of the mixture of fuel and water, a sleeve is inserted into the annular duct between the valve body and valve member in accordance with one embodiment. This sleeve is provided with transverse bores, through which the water is added to the fuel supply and the size and arrangement thereof are formed in such a manner that the water being added flows as far as the base of the sleeve, wherein the chamber below the sleeve remains filled with fuel, preferably diesel fuel. In order to assemble the sleeve in an improved manner it can be formed in a slotted manner. In order to achieve a passage of fuel through the radially inner part of the sleeve and to achieve a water supply radially outside the sleeve, the said sleeve is chamfered on its end, which protrudes into the pressure chamber, in the direction of the water supply line.

In the case of further embodiments the shaft of the valve member comprises in the region of the annular duct different cross-sectional forms which promote the mixture of fuel and water to form an emulsion, which affects the quality of the combustion in an advantageous manner. In order to achieve a improved restricted guidance of the water the cross- section of the pressure chamber can comprise in an advantageous manner an oval shape, wherein the fuel pressure line and the water supply line issue, in each case lying opposite to each other, in to the pressure duct cross-section at the most remote ends thereof. In order to guarantee, in the region in proximity to the valve seat, an upstream storage of unmixed fuel, it is advantageous to provide at this site a reduction in cross-section on the shaft of the valve member which shaft forms an annular chamber in the annular duct.

In addition to the fact that the second supply line issues into the pressure chamber, it is alternatively also possible, to have this second supply line issue in a region, in proximity to the pressure chamber, of the valve member bore. in this case it is advantageous to guide the supplied water by way of a connection duct within the valve member directly into a surface groove on the valve member below the pressure chamber, so that fuel and an additional.medium, in particular water, can be supplied separately to the annular chamber. This structural variation is particularly suitable for layering the injection medium, wherein initially during a pre-injection procedure only fuel is to be injected, then in a second injection pause only water is to be injected and in a third or main injection phase once again almost pure fuel is to be injected. In so doing, the connection duct in the valve member is formed in an advantageous manner in this embodiment by virtue of two chamfered bores, which intersect each other, in the valve member.

A fuel-injection valve, in accordance with the invention, for the purpose of injecting fuel and water can be formed, as in the exemplified embodiments described, as a so-called seat hole nozzle or alternatively as a blind hole nozzle or pintle nozzle. Furthermore, the fuel-injection valve in accordance with the invention can be used in all known fuelinjection devices such as, for example, pump-nozzle devices, common-rail and pump-line-nozzle-injection devices.

Further advantages and advantageous embodiments of the subject 6 matter of the invention are evident in the drawing, the description and in the claims.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, in which.- Figure 1 shows a simplified sectional illustration of the fuel-injection valve which is inserted into the cylinder head of an internal combustion engine, Figure 2 shows a first exemplified embodiment in an enlarged sectional illustration of Figure 1 in which the part embodying the present invention, of the valve body and the valve member is illustrated, Figure 3 shows a second exemplified embodiment similar to the illustration of Figure 2, in which a sleeve is inserted into the annular duct 1 between the valve body and the valve member, Figure 4 shows a third exemplified embodiment similar to the illustration of Figure 2, in which the valve member comprises grooves in the region of the annular duct, Figure 5 shows a fourth exemplified embodiment similar to the illustration of'Figure 2, in which the valve member comprises in the region of the annular duct a square profile, 7 Figure 6 shows a first sectional view of the square profile of the valve member of Figure 5, Figure 7 shows a second sectional view of Figure 5 along the pressure duct, Figure 8 shows a fifth exemplified embodiment similar to the illustration of Figure 2, in which the shaft of the valve member comprises a tooth profile, Figure 9 shows a sectional view of Figure 8 along the pressure chamber, and Figure 10 shows a sixth exemplified embodiment similar to the illustration of Figure 2, in which the second supply line is connected to the annular duct by way of a connection duct in the valve member.

The first exemplified embodiment, shown in Figure 1 and in Figure 2 in an enlarged section of Figure 1, of the fuel-injection valve for internal combustion engines in accordance with the invention comprises a valve body 3 which is inserted into a housing 1 of an internal combustion engine, preferably the cylinder head thereof, and which protrudes with its lower end into the combustion chamber of the internal combustion engine to be supplied. In the valve body 3 there is provided an axial blind hole bore 7 which issues from an upper end face 5 remote from the combustion chamber, in which blind hole 8 bore a piston-shaped valve member 9 is guided in an axially displaceable manner. This valve member 9, which is illustrated in an enlarged manner in Figure 2, comprises on its lower combustion chamberside end a conical valve sealing surface 11, with which the said valve member cooperates with a likewise conical valve seat surface 13 at the closed end of the bore 7. The valve member 9 comprises on its shaft a pressure shoulder 15 which acts in the opening direction of the valve member and which protrudes into a pressure chamber 17 which is formed by a widening of the cross-section of the bore 7. A pressure duct 19, which issues from the end face 5 and extends in an inclined manner, issues into this pressure chamber 17 and on the other side is connected to a fuelinjection line 21 which is illustrated in a simplified manner in Figure 1 and by way of which the pressure chamber 17 is supplied with high pressure fuel from a high pressure injection pump [not illustrated]. Between the pressure chamber 17 and the valve seat 13 there is formed an axial annular duct 23 between the wall of the bore 7 and the valve member shaft 9, by way of which annular duct the fuel passes from the pressure chamber 17 to the valve seat 13. On the side, remote from the annular duct 23, of the valve seat surface 13 injection orifices 25 in the form of through-going injection bores lead off and issue into the combustion chamber of the internal combustion engine to be supplied.

As illustrated in Figure 1, the valve body 3 is clamped by means of a tensioning nut 27 in an axial manner against a valve holding body 29, wherein an intermediate disc 31 is clamped between the valve body 3 and the valve holding body 29. In so doing, a valve spring 33 is inserted in the valve holding 9 body 29 and influences the valve member 9 by way of a spring plate 35 and a pressure piece 37 in the closing direction against the valve seat 13.

In order to supply a second injection medium, preferably water, the valve body 3 also comprises a second supply line 39 which is disposed lying opposite to the pressure duct 19 and extends, issuing from the end face 5, in an inclined manner as far as into the pressure chamber 17. The second supply line 39 is connected by way of a supply line 41, which penetrates the intermediate disc 31 and the valve holding body 29 in an axial manner, to a connection piece 43 which for its part is connected [in a manner which is not illustrated in detail] to a water delivery device.

In order to avoid a back-flow or back-pressure of water in the direction of the connection piece 43 and/or delivery pump, a non-return valve 45, which opens in the direction of the injection orifice 25, is inserted into the supply line 41, preferably in the region of the intermediate disc 31.

A fuel-injection valve for internal combustion engines in accordance with the invention functions in the following manner. Prior to the commencement of the injection procedure water is delivered into the fuel- filled pressure chamber 17 by way of the supply line 41 and the second supply line 39, wherein during the injection pauses the delivery pressure of the water is greater than the static pressure of the residual fuel remaining in the fuel-injection valve. The water delivery pressure amounts preferably to between 30 and 100 bar, whereas the remaining fuel static pressure is approximately 20 bar, however a maximum of 70 bar. The water which is urged into the pressure chamber 17 displaces the fuel, which remains in the pressure chamber 17 and partially in the annular duct 23, back into the pressure duct 19. Only in proximity to the valve seat surface 13 does a predetermined residual amount of pure fuel remain in the annular duct 23, whereas water or a fuellwater emulsion accumulates in the other annular duct region and in the region of the pressure chamber 17.

At the commencement of a fuel-injection procedure at the fuel-injection valve extremely high pressure fuel, preferably up to 1800 bar, is delivered into the pressure chamber 17 by the injection pump by way of the injection line 21 and further by way of the pressure duct 19. At this site the high pressure fuel acts in a known manner upon the pressure shoulder 15 of the valve member 9 and displaces the valve member 9 from the valve seat 13 against the restoring force of the valve spring 33 after the opening pressure has been exceeded. As the orifice cross- section is opened, pure fuel flows initially by way of the injection orifices 25 into the combustion chamber of the internal combustion engine to be supplied and at this site initiates the combustion by way of a socalled pre-injection procedure. Following on from this pre-injected pure fuel, the fueilwater emulsion located in the annular duct 23 passes at this point to the injection procedure which delays any further combustion and which in the further progression is followed by the main injection of pure fuel. In so doing, it is possible by virtue of the intermediate injection of the fueilwater emulsion that the fuel-injection procedure can be subdivided into a small pre-injection quantity and a main injection quantity. The water-carrying second supply line 39 is sealed in a hydraulic manner by virtue of the high pressure fuel flowing into the pressure chamber 17, so that during the main injection phase it is not possible for water from the second supply line 39 to issue into the pressure chamber 17. The non-return valve 45 prevents any water from flowing back in the direction of the connection piece 43 and/or delivery pump. Since the pressure duct 19 and the second supply line 39 have to render possible extremely different high through-flow quantities, the through- flow cross-section of the pressure duct 19 is formed in an advantageous manner to be larger than the through-flow cross-section of the second supply line 39.

At the end of the fuel-injection procedure the supply of high pressure fuel into the injection line 21 is interrupted, so that the pressure in the pressure chamber 17 drops again below the opening pressure of the valve member 9 and at this point the closing force of the valve spring 33 is sufficient to displace once again the valve member 9 with its valve sealing surface 11 in position against the valve seat surface 13, so that Lhe injection valve closes. In so doing, the fuel pressure in the injection line 21 and in the pressure duct drops again below the pressure of the water which has been delivered, so that in turn water issues by way of the second supply line 39 into the pressure chamber 17 and into parts of the annular duct 23 and displaces the fuel located therein back into the pressure duct 19. Once again a new layered arrangement of fuel and water is provided in the pressure chamber 17 and the annular duct 23 in the manner described above.

The second exemplified embodiment shown in Figure 3 differs from the first exemplified embodiment, which is illustrated in Figure 2, by virtue of a sleeve 47 which is additionally inserted into the annular duct 23 and divides the annular duct 23 into a radially inner-lying region 49 and into a radially outerlying region 51. These regions 49 and 51 are mutually connected by way of a 12 plurality of bores 53 in the sleeve 47. The sleeve 47 comprises on its end facing the injection orifice 25 an enlarged diameter annular collar 55 with which the sleeve 47 is clamped at this site in a sealing manner on the wall of the bore 7, so that the outer region 51 is sealed in the direction of the injection orifice 25. At its upper end which protrudes into the pressure chamber 17 the sleeve 47 is chamfered in an ascending manner in the direction of the opening of the second supply line 39. In this manner it is possible for the water quantity flowing in through the second supply line 39 to be guided into the outer region 51 of the annular duct 23 and to pass only by way of the bores 53 of the sleeve 47 to the region in proximity to the valve seat. In contrast, the fuel which flows by way of the pressure duct 19 is supplied not only to the outer region 51 but mainly to the inner region 49 of the annular duct 23, so that the said fuel can flow unhindered and thus as rapidly as possible to the valve seat 13. By virtue of the arrangement and formation of the bores 53 in the sleeve 47 the mixture of fuel and water can be influenced so that the most advantageous emulsion possible can be produced.

The third exemplified embodiment illustrated in Figure 4 comprises on the shaft, which protrudes into the annular duct 23, of the valve member 9 a plurality of longitudinal grooves 57, preferably six longitudinal grooves 57. In so doing, these axial longitudinal grooves 57 extend at their upper end as far as into the pressure chamber 17 and issue with their lower end, facing the injection orifice 25, into a lower annular chamber 59 in the bore 7. This annular chamber 59 in the annular duct 23 is formed by virtue of a reduction in cross-section of the valve member cross-section and is separated from the 13 valve seat surface 13 by virtue of a remaining annular cross piece 61. By virtue of the formation of the valve member shaft as shown in Figure 4 it is possible to supply the fuel and water almost separately to the annular chamber 59, so that it is possible to achieve a favourable layered arrangement of water and fuel.

The fourth exemplified embodiment, illustrated in Figures 5 to 7, of the fuel-injection valve in accordance with the invention differs from the third exemplified embodiment illustrated in Figure 4 by virtue of the formation of the valve member shaft in the region of the annular duct 23. In the region of the annular duct 23, as is also evident in the sectional illustration as shown in Figure 6, the shaft of the valve member 9 comprises a square profile 63. Furthermore, the cross-section of the pressure chamber 17 is oval, as shown in the sectional illustration of Figure 7, wherein the second supply line 39 and the pressure duct 19 issue, in each case lying opposite each other, into the pressure chamber 17 at the remotest ends of the oval pressure duct crosssection.

The fifth exemplified embodiment, illustrated in Figures 8 and 9, of the fuel-injection valve in accordance with the invention comprises a tooth profile 65 on the shaft of the valve member 9 in the region of the annular duct 23, which tooth profile extends in an axial manner from the pressure chamber 17 as far as into the annular chamber 59. Furthermore, the pressure chamber 17, as illustrated in Figure 9 in the sectional view of Figure 8, is formed in the shape of a long-hole cross-section.

In the case of the sixth exemplified embodiment illustrated in Figure 10 14 the water from the second supply line 39 is supplied, in contrast to the aforementioned exemplified embodiments, by way of a connection duct in the valve member 9, wherein the water flowing in does not flow through the pressure chamber 17. The second supply line 39 in the valve body 3 above the pressure chamber 17 issues into the blind bore 7, wherein in the region of the opening an annular chamber is provided between the valve member 9 and the wall of the bore 7 and in the exemplified embodiment said annular chamber is formed by virtue of an annular groove 67 in the valve member 9. A connection duct 69, which is formed by virtue of two chamfered bores, in the valve member 9 leads off from this annular groove 67 and issues into the annular duct 23 below the pressure chamber 17. In the region of the annular duct 23 there are provided two axial surface grooves of which a first surface groove 71 extends from the pressure chamber 17 as far as into the annular chamber 59 and by way of which the fuel supplied by way of the pressure duct 19 is guided to the valve seat 13. The second surface groove 73 commences in the region of the opening of the connection duct 69 below the pressure chamber 17 and extends likewise as far as into the annular chamber 59. The water which flows into the connection duct 69 by way of the second supply line 39 flows by way of this second surface groove 73 into the annular chamber 5:9, wherein the connection duct 69 forms a bypass line with respect to the pressure chamber 17. The sixth exemplified embodiment has the advantage that the water supplied can be guided separately into the annular duct 23 and thus it is possible to achieve an extremely homogeneous layered arrangement of fuel, water and fuel again, by way of which it is possible to control precisely the pre-injection quantity and the main injection quantity of the fuel which is to be injected.

Claims

16 CLAIMS

1. Fuel-injection valve for internal combustion engines having a valve member which is guided in an axially displaceable manner in a bore of a valve body and which comprises on its combustion chamber-side end a valve sealing surface, with which, for the purpose of controlling an injection cross-section, the said valve member cooperates with a housingfixed valve seat surface, and having a pressure shoulder, which acts in the opening direction of the valve member, on the shaft of the valve member, which pressure shoulder protrudes into an enlarged cross-section pressure chamber, into which, furthermore, issues a pressure duct which can be connected to a high pressure fuel source, wherein the pressure chamber is connected to the valve seat surface by way of an axially extending annular duct formed between the valve member shaft and the wall of the bore, and having a second supply line in the valve body, by way of which second supply line a second medium is supplied to the injection cross- section of the injection valve, and wherein the second supply line extends completely in the valve body and issues directly into the pressure chamber or at least in proximity to the pressure chamber into a chamber which is defined between the valve member and the wall of the bore.

2. Fuel-injection valve according to claim 1, wherein water is supplied to the injection cross-section as the second medium.

3. Fuel-injection valve according to claim 1, wherein the second supply line comprises a smaller through-flow cross-section than the fuelcarrying pressure duct.

4. Fuel-injection valve according to claim 3, wherein the second supply 17 line is connected to a connection piece of a delivery line by way of a supply line, and wherein a non-return valve which opens in the direction of the injection orifice is inserted into the supply line.

5. Fuel-injection valve according to claim 1, wherein during the injection phase at the injection valve the fuel pressure in the pressure duct is grealer than the pressure of the second medium in the second supply line.

6. Fuel-injection valve according to claim 1, wherein during the injection pauses the pressure of the second medium in the second supply line is greater than the static pressure of the fuel in the pressure duct.

7. Fuel-injection valve according to claim 1, wherein the pressure chamber comprises an oval cross-sectional shape and that the second supply line and the fuel pressure duct issue, in each case lying opposite each other, into the pressure duct cross-section at the remotest ends thereof.

8. Fuel-injection valve according to claim 1, wherein a sleeve is inserted into the axial annular duct and subdivides the annular duct into a radially innerlying region and into a radially outer-lying region, wherein these regions are mutually connected by way of a plurality of bores in the sleeve.

9. Fuel-injection valve according to claim 8, wherein the sleeve, at its end facing the valve seat, is clamped in a sealing manner on the wall of the bore and that the end facing the pressure chamber is chamfered in an ascending manner in the direction of the opening of the second supply line 10. Fuel-injection valve according to claim 1, wherein the shaft of the valve member comprises a plurality of longitudinal grooves, preferably six, in the region of the annular duct.

18 11. Fuel-injection valve according to claim 1, wherein the shaft of the valve member comprises a square profile in the region of the annular duct.

12. Fuel-injection valve according to claim 1, wherein the shaft of the valve member comprises a tooth profile in the region of the annular duct.

13. Fuel-injection valve according to claims 10, 11 or 12, wherein in the region of the annular duct the valve member comprises a reduction in crosssection between the lower end, facing the valve seat, of the profiled surfaces on the valve member shaft and the valve sealing surface which forms an enlarged cross-section annular chamber in the annular duct.

14. Fuel-injection valve according to claim 1, wherein the second supply line above the pressure chamber issues into the bore, and wherein in the opening region an annular chamber is provided between the valve member and the bore wall, from which annular chamber leads off a connection duct within the valve member, which connection duct issues into the annular duct downstream below the pressure chamber.

15. Fuel-injection valve according to claim 14, wherein on the shaft of the valve member in the region of the annular duct there are provided at least two surface grooves, which issue into the annular chamber and of which a first surface groove protrudes with its upper end into the pressure chamber and a second surface groove terminates below the pressure chamber, wherein the connection duct in the valve member issues into the second surface groove.

16. A fuel-injection valve for internal combustion engines, substantially as hereinbefore described with reference to Figs. 2 to 10 of the accompanying drawings.