GB2310250A

GB2310250A - Fuel injection valve for internal combustion engines

Info

Publication number: GB2310250A
Application number: GB9701703A
Authority: GB
Inventors: Karl Hofmann
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1996-02-17
Filing date: 1997-01-28
Publication date: 1997-08-20
Anticipated expiration: 2017-01-28
Also published as: GB9701703D0; DE19605956A1; GB2310250B; JPH09222062A

Description

1 1 1 2310250 Fuel ig-jection valve for internal combustion -"

Background art

The invention proceeds from a fuel injection valve for internal combustion engines according to the prewnble oftlaim 1. Such a fuel injection valve known firom EP 0 418 271 B 1 comprises a cylindrical valve body, the external diameter of which is reduced so as to form an annular shoulder in the direction of an injection opening. The valve body is braced by means of a clamping nut, which is applied against the annular shoulder, axially towards a retaining body and inserted with said clamping nut into a stepped location bore in the housing of the i. c. engine, the reduced-diameter portion of said bore opening into the combustion chamber of the i.c. engine. Sealing of the combustion chamber- side portion of the location bore in the housing of the i.c. engine is effected by means of a sealing ring, which is clamped in between the annular end face of the clamping nut and the housing step of the location bore.

From background art it is known to select the dimensions of said sealing ring in such a way that the sealing ring is slidingly guided either on the stem of the valve body or by its external diameter against the wall of the location bore.

In the known fuel injection valves the drawback however arises that, upon removal of the fuel injection valve from the housing of the i.c. engine, the sealing ring remains in the location bore in the housing (cylinder head) of the i. c. engine, from which it is removable only with quite a substantial effort.

Advantages of the invention In contrast, the fuel injection valve for i.c. engines according to the invention 2 having the characterizing features of claim 1 has the advantage that the sealing ring is disposed in an axially secured manner on the stem of the valve body, thereby guaranteeing that it may be removed jointly with the valve body of the fuel in. ection valve from the location bore.

9 An important point here is that the sealing ring is to be fastened in such a manner on the valve body stem that it transmits loads to the valve body or deforms the valve body as little as possible. A constriction or deformation of the valve body stem may impair the very low-play guidance between valve body and the valve element (valve needle) axially movable therein, which may lead to jamming of the valve element and hence to imprecise opening and closing and further to failure of the invention valve.

The sealing ring is therefore advantageously fastened by means of frictional locking on the valve body stern, said frictional locking preferably being built up only in sub-regions which are distributed symmetrically over the circumference.

In an advantageous manner, said sub-regions are formed by three radially inwarddirected projections on the inner wall surface of the sealing ring which have a reduced cross section compared to the sealing ring thickness, a possible alternative being two or more projections. The projections are preferably of a radius-shaped construction and have, at their transitional surface to the internal diameter of the sealing ring which is directed towards the clamping nut, a chamfering angle or radius which enables the sealing ring to be pushed easily and uniformly onto the valve body stem. In order moreover to ensure that the valve body is not deformed, the sealing ring is advantageously made of a softer material than the valve body, preferably of copper.

Manufacture of the three projections is advantageously effected by means of a 3 triangular punch having a shape, by means of which the internal diameter of the three projections is simultaneously stamped (e.g. 7 +/0.05 mm), with the result that the latter may be precisely manufactured easily and in a single operation.

A further possibility of manufacturing the, preferably, three projections is a punching process whereby, except for the profile of the three projections, the remaining material of the sealmig ring is punched out.

The projections are moreover so dimensioned that they deform easily under load and hence transmit only low retaining loads to the valve body stem.

Further advantages and advantageous refinements of the subject matter of the invention are indicated in the description, the drawings and the claims.

Drawings An embodiment of the fuel injection valve for i.c. engines according to the invention is illustrated in the drawings and described in detail below.

Figure 1 shows a view of the complete injection valve with a sealing ring pushed thereon, Figure 2 an enlarged detail from Figure 1 in the region of the sealing ring with the position of installation into the location bore of the housing of the i.c. engine, Figure 3 an enlarged view of the sealing ring and the triangular punch and Figure 4 a sectional view of the sealing ring.

4 Description of the embodiment

The fuel injection valve for i.c. engines, of which a complete view is shown in Figure 1 and an enlarged detail is shown in Figure 2, comprises a cylindrical valve body 1, the external diameter of which is reduced to form an annular shoulder 3, the reduced-diameter stem part 7 havm"g at its free end at least one injection opening 5 which opens into the combustion chamber (not shown in detail) of the i.c. engine. The valve body 1 at its end remote from the injection opening 5 is braced by means of a clamping nut 9, which is applied against the annular shoulder 3, axially towards a retaining body 11, which has a connection port 13 for an injection line (not shown) leading to an injection pump and in which a pressure channel 15 is provided for supplying the highly pressurized fuel to the injection valve. A valve element, which by means of its travel opens or closes an opening cross section in the injection valve, is in a known manner guided axially in the valve body 1.

The injection valve is inserted into a stepped location bore 17, which is shown in Figure 2, in the housing 19 (cylinder head) of the i.c. engine to be supplied, the reduced-diameter region of said location bore opening into the combustion chamber of the i.c. engine. For sealing the combustion chamber-side portion of the location bore 17, a sealing ring 21 is clamped in between an annular end face 23 of the clamping nut 9 and a housing step 25 formed at the cross-sectional transition of the location bore 17 and is guided on the stem 7 of the valve body 1.

Said sealing ring 2 1, two enlarged views of which are shown in Figures 3 and 4 and which is preferably made of copper, has three radially inwarddirected projections 27, the cross section of which is reduced compared to the sealing ring thickness and which lie with their radially inwardprojecting ends against the wall of the valve body stem 7 so as to form a frictional lock. For symmetrical support and load introduction, said projections are moreover distributed uniformly over the circumference of the sealing ring internal diameter.

In order to guarantee that any loads which arise lead to a deformation of the projections 27 of the sealing ring 21 and not to a deformation of the valve body stem 7, the cross section of the projections 27 decreases in a radially inward direction, to which end the projections 27 in a radial cutting plane through the sealing ring 21 are of a radius-shaped construction.

Furthermore, the clamping nut-side transition between the projections 27 and the internal diameter of the sealing ring 21 has a radius R which makes it easy to push or press the sealing ring 21 onto the stem 7 of the valve body 1.

The projections 27 are introduced into the sealing ring 21 by means of a triangular punch 29 diagrammatically illustrated in Figure 3, which is applied against the end face 31 of the sealmig ring 21 remote from the clamping nut 9 and is constructed in such a way that, while introducmig the projections 27, it simultaneously produces the required dimension for the internal diameter D of the projections 27.

The projections 27 on the sealing ring 21 may alternatively be produced by punching out the internal contour of the sealing ring 2 1, in which case except for the projections 27 the remaining material at the recesses Mi between is removed.

The sealing ring 21 is then pushed uniformly onto the valve body stem 7 of the preassembled injection valve up to contact with the annular end face 23 of the clamping nut 9, thereby producing between the radially inward-directed ends of the projections 27 and the wall of the valve body stem 7 a ffictional lock, the tension of which is supported mainly by a deformation of the projections 27 on the sealing ring 2 1.

6 Thus, in a constructionally simple manner it is Possible to fasten the sealing ring 21 as an assembly unit on the stem 7 of the valve body 1 without impairing the function of the injection valve.

7

Claims

Claijrns

1.

2.

3.

4 Fuel injection valve for i.c. engines, comprising a cylindrical valve body (1), the external diameter of which is reduced so as to form an annular shoulder (3) in the direction of an injection opening (5) and which is axially braced towards a retaining body (11) by means of a clamping nut (9) applied against the annular shoulder (3), the fuel injection valve being inserted into a stepped location bore (17) in the housing (19) of the i.c. engine, which bore is sealed off by means of a sealing ring (2 1) which is clamped in between an annular end face (23) of the clamping nut (9) and a housing step (25) of the location bore ( 17), characterized in that the sealing ring (2 1) is disposed in an axially secured manner on the reduceddiameter stem part (7) of the valve body (1).

Fuel injection valve according to claim 1, characterized in that the sealing ring (21) is fixed by means of frictional locking in its position on the stem (7) of the valve body (1).

Fuel injection valve according to claim 2, characterized in that the sealing ring (21) is applied only by sub-regions of its inner wall surface of the sealing ring bore against the valve body stem (7), said contact regions being distributed uniformly over the circumference.

Fuel injection valve according to claim 3, characterized in that disposed on the inner wall surface of the sealing ring (21) are preferably three radially inward-directed projections (27), the cross section of which is reduced compared to the sealing ring thickness.

8 5.

6.

7.

8.

9.

Fuel injection valve according to claim 4, characterized in that the cross section of the projections (27) decreases in a radially inward direction.

Fuel injection valve according to claim 4, characterized Mi that the projections (27) in a radial cutting plane of the sealing ring (2 1) are designed with a curvature having a specific radius.

Fuel injection valve according to claim 4, characterized in that the radially projecting end of the projections (27) at its side directed towards the clamping nut (9) has a radius (R).

Fuel injection valve according to claim 1, characterized Mi that the sealing ring (2 1) is made of a softer material than the valve body (1), preferably of copper.

Method of manufacturing the projections (27) according to claim 4, characterized in that the three projections (27) are formed by means of a triangular punch (29), which is applied against the end face (3 1) of the sealing ring (21) remote from the clamping nut (9) and is constructed in such a way that, while forming the projections (27), it simultaneously produces the required dimension for the internal diameter (D) of the radially inward-directed ends of the projections (27).

Method of manufacturing the projections (27) according to claim 4, characterized in that the internal annular contour of the sealing ring (2 1) is formed by punching out the material between the projections (27).

9 11.

12.

A fuel injection valve substantially as herein described with reference to the accompanying drawings.

A method of manufacturing projections on the inner wall surface of a sealing ring of a fuel injection valve, substantially as herein described with reference to the accompanying drawing.