GB2310890A

GB2310890A - Fuel injection valve for internal combustion engines

Info

Publication number: GB2310890A
Application number: GB9702681A
Authority: GB
Inventors: Karl Hofmann; Erguen Filiz; Rainer Naumann; Friedrich Boecking
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1996-03-06
Filing date: 1997-02-10
Publication date: 1997-09-10
Anticipated expiration: 2017-02-10
Also published as: KR100480850B1; GB9702681D0; GB2310890B; KR970065370A; FR2745852A1; JPH09242649A; DE19608575A1; DE19608575B4

Description

1 1 Fuel 1UJection valve for internal combustion engwes

Background art

2310890 The invention proceeds from a fuel injection valve for internal combustion engines according to the preamble of claim 1. Such a fuel injection valve known from DE 44 08 245 A l comprises a valve body, in which a movable valve element is guided in an axially displaceable manner and which projects with its one end into the combustion chamber of the i. c. engmie to be supplied. The valve body is braced with its end remote from the combustion chamber axially against a valve-retaining body by means of a clamping nut, an intermediate disc being clamped in between the end face of the valve body remote from the combustion chamber and the bottom end face of the valve-retaining body directed towards the combustion chamber. Said intermediate disc lies with its axial end faces sealingly against the end faces of the valve body and the valve-retaining body and has a central through-opening for receiving a thrust piece, which is applied axially against the end of the valve element remote from the combustion chamber. There is further provided in the intermediate disc an obliquely extending connection bore, which connects the two parts of the fuel intake bore in the valve body and in the valve-retaining body.

Provided 'm the valve-retaining body is a central blind hole, which emanates from the end face directed towards the combustion chamber and forms a spring chamber for receiving a valve spring which loads the valve element in closing direction.

Sealmig at the corresponding end faces of intermediate disc and valve body or valveretaining body is effected by means of the surface pressure at the end faces, which is dependent upon the bracm'g force at the clampmg nut. The result is a force introduction characteristic at the surfaces with a very high surface pressure in the radially outer region and a reduction of force towards the centre, which is further promoted by the blind hole in the valve-retaining body because in said region no force

2 introduction may be effected. Said non-uniform force introduction impairs the sealing action at the intermediate disc M" the latter's radially inner region so that the known seal does not meet the high standards demanded in particular for injection valves operating at very high injection pressures.

Advantages of the invention In contrast, the fuel injection valve for i.c. engines according to the invention having the characterizing features of claim 1 has the advantage that, as a result of the purposefidly crowned shape of at least one of the cooperating end faces on the intermediate disc and on the valve body, a uniform distribution of force over the sealmg cross section is achieved so that, even in the radially inner region of the injection valve, a sufficiently high sealing action is achieved. It is alternatively possible for the end face on the intermediate disc, the end face on the valve body remote from the combustion chamber or both end faces to be fashioned in an outwardly crowned manner. When providing only one curved end face, the crown of the crowned end face disposed in the axis of the injection valve is to protrude about 0. 00 1 to 0. 002 mm beyond the annular edge which delimits the end face in a radially outward direction. When both cooperating end faces are curved outwards in a crowned manner, said dimension is to be in each case about 0.0005 to 0.001 nun. In the braced state of installation of the structural parts, an elastic deformation is then effected at the crowned end faces in such a way that a plane sealing surface arises.

A crowned construction of the top end face of the intermediate disc directed towards the valve-retaining body and of the cooperating bottom end face of the valve-retaining body directed towards the combustion chamber is a It ernatively possible but has a relatively poor effect there on account of the large opening towards the spring chamber in the valve-retaining body.

Further advantages and advantageous refinements of the subject matter of the 3 invention are indicated in the description, the drawings and the claims.

Drawings Three embodiments of the fuel injection valve for i.c. engines according to the invention are illustrated m the drawings and explained in detail in the following description.

Of the drawings, Figure 1 shows a sectional view of the assembled injection valve, Figure 2 a detail from Figure 1 with a first embodiment in which the end face on- the intermediate disc is crowned and the end face on the valve body is plane, Figure 3 a second embodiment analogous to Figure 2 in which the end face on the intermediate disc is plane and the end face on the valve body is crowned, and Figure 4 a third embodiment analogous to the view of Figures 2 and 3 in which the end faces on the intermediate disc and on the valve body are crowned.

Description of the embodiments

The fuel injection valve for 1.c. engines, which is shown in the assembled state mi Figure 1, comprises a rotationally symmetric valve body 1 which is braced by means of a clarripmg nut 3 axially against a valve-retaining body 5, an intermediate disc 7 being clamped in between the valve body 1 and the valve-retaining body 5. The valve body 1, which projects with its free end into a combustion chamber (not shown in detail) of the 1. c. engine to be supplied, has a blind hole 11, which emanates from the end face 9 of the valve body remote from the combustion chamber and adjacent to the intermediate disc 7 and in which a piston- shaped valve element 13 is guided in an axially displaceable manner. The blind hole 11 at its closed end forms an inverted valve seat 15, which is disposed 'm firont of at least one injection opening 17 into the combustion chamber of the 1.c. engmie and cooperates with a valve sealing surface 19 disposed on the end face of the valve element 13.

4 The blind hole 11 serving as a pilot bore for the valve element 13 is widened at one point to form a pressure chamber 2 1, in the region of which the valve element 13 has a pressure shoulder 23 and which is connected by an intake bore 25 axially penetrating the valve body 1 and the valve-retaining body 5 to a connection port 27 on the valveretaining body 5. Connected to said connection port 27 is a fuel injection line (not shown) to a high-pressure injection pump which alternately loads the injection valve with fuel high pressure.

For receivmg a valve spring designed as a helical pressure spring, there is formed in the valve-retaining body 5 a spring chamber 31 in the form of a central blind hole, which is open towards the interniediate disc 7 and on the bottom of which the valve spring 29 is supported by its one end via an annular disc 33. With its other end situated close to the intermediate disc 7, the preloaded valve spring 29 presses the valve element 13 via a spring cup 35 into contact with the valve seat 15. The valve element 13 at its end remote from the combustion chamber has a thrust piece 37, which is reduced in diameter compared to the valve element stem and projects through a central through-opening 39 in the intermediate disc 7.

For connecting the two parts of the intake bore 25 in the valve body 1 and 'm the valve-retaining body 5, a connection bore 41 is further provided in the intermediate disc 7 and extends obliquely relative to the valve axis.

Removal of leakage oil from the spring chamber 31 is effected via a leakage oil channel 43, which emanates from said spring chamber and opens into a leakage oil connection port 45 at the lateral surface of the valveretaining body 5.

For sealing the nimer chambers of the injection valve through which fuel flows, the bottom end face 47 of the intermediate disc 7 directed towards the combustion chamber and the top end face 49 remote from the combustion chamber are respectively applied sealingly against the end face 9 of the valve body 1 remote from the combustion chamber and the bottom end face 51 of the valve retaining body 5 directed towards the combustion chamber.

In order, in so doing, to achieve a uniform introduction of force over the sealing surface between the intermediate disc 7 and the valve body 1, at least one of the cooperating sealing surfaces is curved outwards in a crowned manner.

The three embodiments which are illustrated in Figures 2 to 4 in an enlarged and simplified detail from Figure 1, are then possible.

In the case of the first embodiment illustrated mi Figure 2, the end face 9 of the valve body 1 remote from the combustion chamber is plane. The cooperating bottom end face 47 of the intermediate disc 7 has an outwardly (downwardly) curved crowned shape, the crown of said curved surface lying in the valve element axis. The maximum extension X of the crown of the crowned end face 47 beyond the edge delimiting the end face 47 in a radially outward direction is about 0.001 to 0.002 mm.

In the case of the second embodiment illustrated in Figure 3, the bottom end face 47 of the intermediate disc 7 is plane and the cooperating end face 9 of the valve body 1 remote from the combustion chamber is curved outwards (upwards) Mi a crowned manner. Here too, the crown of the crowned end face 9 extends through the valve element axis and the maximum height X of the curved surface is about 0.001 to 0.002 mm.

In the case of the third embodiment illustrated in Figure 4, both cooperating end faces 47, 9 on the intermediate disc 7 and on the valve body 1 are curved in a crowned manner, the crowns of the curved surfaces lying in the valve element axis. Here, however, the maximum height X of the crowns of the curved surfaces above the base diameter of the edge at the radial rims is in each case only about 0.0005 to 0.001 nun.

6 During assembly of the injection valve and axial bracing of the valve body 1 and the intermediate disc 7 against the valve-retaining body 5, an elastic deformation is effected at the slightly curved end faces and results 'm a plane, highly scaling application of the Mitermediate disc 7 against the valve body 1. As a result of the curved or spherical seginentshaped construction of the sealing surfaces, a uniform distribution of force over the entire radial region is advantageously achieved, which especially mi the radially nimer region improves the sealing action compared to known fuel injection valves.

7

Claims

1. Fuel injection valve for internal combustion engines, comprising a valve body (1), in which a valve element (13) is guided in an axially displaceable manner and which is braced axially against a valve-retaining body (5) by means of a clampffig nut (3), an intermediate disc (7) being clamped in between the valve body (1) and the valve-retaining body (5) and lying with its end faces (47, 49) sealingly against the axial end faces (9, 5 1) of the valve body (1) and the valve-retaining body (5), characterized in that at least one of the cooperating end faces (9, 47) on the valve body (1) and on the intermediate disc (7) is curved outwards in a crowned manner.

2. Fuel injection valve according to claim 2, characterized in that the end face (9) of the valve body (1) remote from the combustion chamber is crowned and the cooperating bottom end face (47) of the intermediate disc (7) directed towards the combustion chamber is plane.

Fuel injection valve according to claim 1, characterized in that the end face (9) of the valve body (1) remote from the combustion chamber is plane and the cooperating bottom end face (47) of the intermediate disc (7) directed towards the combustion chamber is crowned.

Fuel injection valve according to claim 1, characterized in that the end face (9) of the valve body (1) remote from the combustion chamber and the cooperating bottom end face (47) of the intermediate disc (7) directed towards the combustion chamber are crowned.

Fuel injection valve according to claim 2 or 3, characterized in that the crowned end face (9, 47) at the crown protrudes about 0. 00 1 to 0. 002 mm beyond the edge delimiting the end face mi a radially outward direction.

8 6. Fuel injection valve according to claim 4, characterized in that the crowned, cooperating end faces (9, 47) at their crowns protrude in each case about 0.0005 to 0.001 mm beyond the edges delimiting the end faces in a radially outward direction.

7. Fuel injection valve according to claim 1, characterized in that the valve body (1), for receiving the valve element (13), has an axial blind hole (11), which emanates from the end face (9) remote from the combustion chamber and which by means of a cross-sectional enlargement forms a pressure chamber (21), opening into which is an intake bore (25) emanating radially outside of the blind hole (11) from the end face (9) remote from the combustion chamber.

8. Fuel injection valve according to claim 7, characterized in that the intermediate disc (7), for receiving a thrust piece (3 7) disposed at the end of the valve element 13) remote from the combustion chamber, has a through-opening (3 9), which is coaxial to the blind hole (11) mi the valve body (1), as well as a connection bore (4 1) openmig into the intake bore (25).

9.

Fuel injection valve according to claim 8, characterized in that provided in the valve-retaining body (5) is a further part of the intake bore (25), which opens into the connection bore (41) in the intermediate disc (7), as well as a central blind hole, which forms a sprmig chamber (3 1) for receiving a valve spring (29) acting upon the valve element ( 13) and emanates from the end face (5 1) adj oining the intermediate disc (7).

10. Any of the fuel injection valves substantially as herein described with reference to the accompanying drawings.