GB2093116A

GB2093116A - A fuel cooled engine fuel injection nozzle

Info

Publication number: GB2093116A
Application number: GB8202621A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1981-02-17
Filing date: 1982-01-29
Publication date: 1982-08-25
Also published as: IT8219688A0; DE3105685A1; JPS57153957A; FR2500070A1; IT1190687B

Abstract

The return passage 11a for coolant fuel from a chamber adjacent the tip of the nozzle body 2 extends to the spring chamber 7 so that coolant fuel and fuel leaking past the injection valve may return through a common outlet on the nozzle holder 1. A common connector (12), Figs. 1 and 1a (not shown), with supply and return nipples 12c, 12b, or separate supply and return nipples (26, 27), Fig. 2a (not shown), may be provided for the coolant fuel. <IMAGE>

Description

SPECIFICATION A fluid-cooled fuel injection nozzle State of the Art The invention originates from a fluid-cooled fuel injection nozzle according to the preamble to the main claim. With fuel injection nozzles, it is known to provide a cooling chamber through which coolant flows in order to avoid over-heating effects occurring at high temperatures in various combustion engines. Thus, it is known from German OS 24 51 458, to fix a cooling jacket to the nozzle body by soldering, shrinking on or enclosing wherein at least one elastic sealing ring is arranged between the cooling jacket and the nozzle body for sealing towards the outside. As a coolant fuel is used which is supplied to the cooling jacket through a separate coolant supply bore and a separate coolant return bore in the nozzle body and in the nozzle holder.However, such a fuel injection nozzle requires a total of three connecting nipples for the supply and the return of the coolant and for the fuel supply proper as well as a plurality of ducts in the nozzle body and in the nozzle holder separated from one another and which need to be carefully orientated with respect to each other. Frequently, such fuel injection nozzles have an additional leakage oil union for the return of leakage oil which arrives in the return spring chamber through the sealing seat between the valve needle and the nozzle body. Due to this, constructions with increased external dimensions are produced which are complicated and difficult to manufacture.

Thus, there is a need for simplified connection possibilities in fluid-cooled fuel injection nozzles meeting high demands.

Advantages of the Invention The fluid-cooled fuel injection nozzle in accordance with the invention comprising the characterising features of the main claim has the advantage that a simplified arrangement of the cooling and leakage oil lines is provided so that the same or even smaller external dimensions may be achieved as with un-cooled fuel injection nozzles of the same construction, for example hole-type nozzles.

Advantageous further developments and improvements of the fuel injection nozzle set forth in the main claim are made possible by the measures set forth in the sub-claims. The union for the coolant supply and the combined coolant return and leakage oil return through a special annular piece provided with a hollow screw is of special advantage. The coolant supply and return ducts are located in the region of the nozzle body stem in the form of circular segmental recesses in the wall of the cooling jacket surrounding the nozzle body.

Drawing Embodiments of the invention are illustrated in the drawing and are described in detail in the following specification. Figure 1 shows a side view of a first embodiment of a fluid-cooled fuel injection nozzle and Figures 1 A, 1 B and 1 C show side representations in partial section of essential parts of the fuel injection nozzle shown in Figure 1 and Figure 1 D is a section along the line 1 d--l d in Figure 1 , whereas Figure 2 shows a side view of a further embodiment of a fluid-cooled fuel injection nozzle in the form of a hole type nozzle with detailed representation of the arrangement of Figure 2 shown in Figures 2A to 2D; moreover, Figure 2A is a partial representation from the front of the region of the fuel injection nozzle of Figure 2 leading to the union nipple, Figure 2B shows a section along the line 2b-2b of the nozzle shaft, Figure 2C shows a partial longitudinal section corresponding to the line 2c-2c in Figure 2B and Figure 2D shows a section along the line 2d-2d in Figure 2.

Description of the Embodiments The fundamental concept of the present invention consists in conveying the cooling fluid through the spring chamber of the nozzle holder so that the spring chamber which at the same time conveys the leakage oil return flow, favours at least partially coolant supply ducts but replaces coolant return ducts and at least one outwardly leading union nipple can be omitted.

A fuel injection nozzle consisting of a nozzle holder 1 and a nozzle body 2 in the usual manner, in this case in the form of a hole-type nozzle, is illustrated in Figure 1. The nozzle needle (not shown) is sealingly guided in stages in the nozzle body 2 and is arranged for axial displacement wherein the nozzle body and the valve needle bound a pressure chamber (likewise not shown) from which the fuel supplied through a dotted line duct connection 3 and an upper connecting nipple 4 arrives in the combustion chamber of the engine through injection openings after displacement of the valve needle.

The nozzle body 2 is clamped to the nozzle holder 1 by a cap nut 5 with the interposition of a junction disc 6 wherein a space 7 for the closure spring is provided in the nozzle holder. The closure spring, not illustrated in the drawing, is supported on the one hand through a spring plate 8 (see Figure 1 B) on the nozzle needle and on the other hand by the base of the bore of the spring chamber 7.

The enlarged representation in Figure 1C of the nozzle body stem 2a shows the cooling chamber formed as an annular chamber at 8 and which is formed between a cooling jacket 9 fixed to the nozzle stem 2a and the nozzle stem. Moreover, the cooling jacket can be soldered to the nozzle stem; however, other types of fixing are possible, for example by means of a press fit or a shrunk on fit also in association with interposed sealing members. The coolant is supplied to the cooling chamber through a coolant supply line 1 Oa in the nozzle body 2 and is discharged once again through a corresponding coolant return line 1 a.

The supply line 1 Oa and the return line ii a pass through the intermediate disc 6 as lines lOb and 11 b; moreover, the return line 11 b for the coolant issues directly into the spring chamber 7 (see the larger detailed illustration of Figure 1 B) so that the returned coolant combines with the leakage oil in the spring chamber 7. The returned coolant and leakage oil is then conveyed from the spring chamber 7 through a common coolant and leakage oil return line 11 c in the nozzle holder 1 - it being understood that in the normal case the coolant fuel is of the same kind as leaves the spring chamber 7 in the form of leakage oil.The extension of the supply line for the coolant, which in this case is referenced 1 Oc, is also located in the nozzle holder 1 (see Figure 1 together with 1A).

Figures 1 and 1 A show a further special form of the outwardly directed unions for the coolant supply and coolant and leakage oil return. The union is provided in the form of a double nipple 12 with a hollow screw 1 3 wherein, as Figure 1 A shows, the hollow screw is screwed into an internal thread in the nozzle holder 1 at 14. The hollow screw 1 3 acts through a central passage 1 5 which is aligned with the coolant and leakage oil return duct 11 c in the nozzle holder 1.

Simultaneously, the hollow screw 13 supports the double sided connecting nipple 12 on the nozzle holder with the interposition of sealing discs I 6a, 1 6b on each side. The double sided union nipple 12 surrounds a central spherical base portion 1 2a having a central through bore 1 7 for the hollow screw 1 3 the head of which is formed in this case as a hexagonal socket heat for the purpose of fixing. The returned coolant together with the leakage oil then arrives through an annular recess 18 in the hollow screw 13, in the duct 19 as part of the return in the union nipple 1 2b for coolant and leakage oil return lying to the right in the plane of the drawing in the illustrated embodiment.

The coolant (fuel) supplied to the left hand union nipple 1 2c is then conveyed through a downwardly inclined duct 20 as part of the supply to a lower annular groove 20 in the hollow screw 13 - the partial duct 19 is downwardly inclined from the upper annular groove 18 in the hollow screw 1 3 - and from the annular groove 20 through intermediate connecting lines and recesses 22 to the further coolant supply duct 1 Oc referred to above and then through 1 Ob and 1 Oa to the cooling space 8.

The illustration of Figure 1 D shows that the coolant bores in the nozzle body 2 lies in a plane displaced from the centre; the fuel supply line 3 is arranged opposite to the coolant bores.

In the embodiment of Figures 2 together with 2A to 2D, like parts are provided with like references provided with a prime index; the difference in the embodiment of Figures 2 and 2A to 2D is that a union nipple 26 for the coolant supply and a nipple 27 for the coolant and leakage oil return are directly inserted and fixed in a cutout 25 at the top of the nozzle holder 1 ', wherein the left-hand union nipple 26 for the coolant supply is in communication through an inclined bore 27 with the coolant supply ducts 1 Oc' in the nozzle holder and later 1 Oa' in the nozzle body, whereas the combined coolant and leakage oil return duct 28 conveyed through the spring chamber 7' is in communication with the union nipple 27.

The coolant return 11 a' coming from the nozzle body is also in communication with the spring chamber 7' in the arrangement shown in Figure 2 and issues into the spring chamber whereby, as is ciearly shown in Figure 2C, the coolant annular chamber 8' and the supply and return lines 1 Oa' and 11 a' are, in this instance, machined in the cooling jacket fixed to the nozzle body 2a'. In Figure 2D, which shows a cross-section through the nozzle body in the region of the cap nut 5', the fuel supply bore is referenced 3', the coolant supply bore is referenced 1 Oa' and the coolant return bore is referenced 11 a'.

Claims

1. A fluid-cooled fuel injection nozzle for combustion engines comprising a cooling jacket arranged on the nozzle body and bores for the passage of the coolant (fuel) in the nozzle body and the nozzle holder, characterised in that, the coolant supply bore or the coolant discharge bore issues into the spring chamber in the nozzle holder in such a manner that the coolant is conveyed through the spring chamber together with the leakage return oil.

2. A fuel injection nozzle according to claim 1, characterised in that, the coolant return bore issues into the spring chamber in such a manner that the leakage oil return and the coolant return outwardly form a common union.

3. A fuel injection nozzle according to claim 1 or 2, characterised in that, the coolant-return line passing through the nozzle body issues into the spring chamber through an intermediate bore in a disc between the nozzle holder and the nozzle body in the region of the spring plate for the closure spring.

4. A fuel injection nozzle according to one of claims 1 to 3, characterised in that, a double ended union nipple with a hollow screw is provided for the coolant supply on the one hand hand and for the coolant return on the other hand combined with the leakage oil return and is fixed in the nozzle holder.

5. A fuel injection nozzle according to claim 4, characterised in that, the double nipple consists of two opposite union portions and a central spherical base portion which has separate ducts for the coolant supply and leakage oil and coolant return.

6. A fuel injection nozzle according to claim 4 or 5, characterised in that, a central bore in the hollow screw is in communication with the connecting duct from the spring chamber for the coolant return and leakage oil return.

7. A fuel injection nozzle according to one of claims 4 to 6, characterised in that, the hollow screw serving for fixing the double ended union nipple has at least one annular groove in the region of the double nipple base portion.

8. A fuel injection nozzle according to one of claims 4 to 6, characterised in that, the double nipple together with the hollow screw are arranged in an upper recess in the nozzle holder forming a cut-out.

9. A fuel injection nozzle according to one of claims 1 to 3, characterised in that, separate union nipples for the coolant supply on the one hand and the coolant and leakage oil return on the other hand, one of which is in communication with the spring chamber through an intermediate duct are fixed in a cut-out recess.

10. A fuel injection nozzle according to one or more of claims 1 to 9, characterised in that, the annular cooling chamber and the supply and discharge lines supplying the chamber with the coolant (fuel) are formed and machined in the cooling jacket surrounding the nozzle shaft of the nozzle body.

11. A liquid-cooled fuel injection nozzle for combustion engines, through which coolant is conveyed, substantially as herein described with reference to Figure 1 and Figures 1 A to 1 D or Figure 2 and Figures 2A to 2D of the accompanying drawings.