GB2024324A

GB2024324A - Connecting fuel ducts to fuel injectors

Info

Publication number: GB2024324A
Application number: GB7921660A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1978-06-24
Filing date: 1979-06-21
Publication date: 1980-01-09
Also published as: JPS557995A; FR2429330A1; GB2024324B; FR2429330B3; DE2827850A1

Abstract

A fuel injection apparatus for an internal combustion engine comprises an injection valve (1), a fuel duct connecting element (12) pluggable over a portion of the valve (1), and at least one resilient sealing ring (17, 18) so disposed between said portion of the valve (1) and the connecting element (12) as to prevent metallic contact axially and radially of the valve (1) between said portion of the valve (1) and the connecting element (12). <IMAGE>

Description

SPECIFICATION Fuel injection apparatus The present invention relates to a fuel injection apparatus for an internal combustion engine.

In known fuel injection apparatus a plug nipple is located on a connecting stub of a magnetic fuel injection valve by metallic contact. Oscillations emanating from the valve on the opening and closing thereof are directly transferred to a pressure duct. This leads to an unpleasant noise development and to leakage at the connecting points of the pressure duct as a result of continuous shaking thereof.

Since fuels of low boiling point are primarily controlled by these valves, the fire and explosion risk is particularly high in the case of leakages so that the question of the safety of the connections is the first priority. The endeavour to do justice to these demands are evident from an older patent application, in the disclosure of which an injection valve, although decoupled towards the induction duct, is however connected fast with the pressure duct through a screw connection. The pressure duct in turn is resilient, i.e. suspended decoupled towards the engine.

Apart from the screw connection now as before representing the most secure but most expensive connection, the oscillations are transferred from the magnetic valve to the pressure duct and lead to the disadvantages described above.

According to the present invention there is provided a fuel injection apparatus for an internal combustion engine, comprising a valve, a fuel duct connecting element pluggable over a portion of the valve, and at least one resilient sealing ring so disposed between said portion of the valve and the connecting element as to prevent metallic contact axially and radially of the valve portion between the latter and the connecting element.

Embodiments of the present invention will now be more particularly described by way of example and with reference to the accompanying drawings in which: Fig. 1 shows an injection valve in corporated in an induction duct with a connecting element plugged over the valve and Fig. 2 to 6 show different embodiments of the connecting element.

Fig. 1 shows an electromagnetically controlled fuel injection valve 1 tightened through a mounting 2 to a suction duct 3 of an internal combustion engine. The valve 1 protudes into an opening 4 of a connecting stub 5 of the duct 3, whilst a resilient ring 8 is disposed between a shoulder 6 of the magnetic valve 1 and a shoulder 7 in the opening 4. Transmission of oscillations of the magnetic valve 1 to the duct 3 on opening and closing of valve, are prevented by the ring 8. For the same reason, the mounting 2 engages in the same manner of a flange at resilient ring 9, which is force-lookingly disposed around the magnetic valve 1. An electrical connection of the magnetic valve 1 is designated by 10. A fuel connectin takes place through a pressure stub 11 of the valve, over which is plugged a connecting nipple 12, which in turn is connected with a pressure duct 13.

The manner in which the nipple 12 is held in its axial position with respect to the valve 1, can for example take place through a mounting connected with the nipple 12 or indirectly through the pressure duct 13.

In the embodiment shown in Fig. 1, the stub 11 is stepped. Disposed between the steps 14 or 15 and the inside wall of the bore 16 of the nipple 12 are O-rings 17 and 18, which permit a certain axial and radial play between the nipple 12 and stub 11 without metallic contact taking place between the two.

To prevent the nipple 12 being pushed too far onto the stub 11 a widening 19 co-operates with the O-ring 17. The nipple can only be pushed over the stub 11 until the shoulder 20 formed between widening 19 and bore 16 meets the O-ring 17. In order to avoid the O-rings 17 and 18 being also pulled down while drawing the nipple 12 off from the stub 11, a shallow annular groove 21 can be provided in the shell surface of the steps of the stub 11 as indicated for the O-ring 18. A synthetic material ring 22, which is preferably fastened to the stub 11, may be disposed for additional guidance between the stub 11 and the widening 19.

In the embodiment shown in Fig. 2, the stub 11 is provided with only one step 15, on which the O-ring 18 is disposed. An annular groove 23 is provided in the stub 11 for the O-ring 17. Apart from its sealing function the O-ring also acts as a radial guide and further acts as an abutment buffer in the axial direction. For this, the O-ring 18 bears against the shoulder 24 formed by the step 15 and against the shoulder 20 in the nipple 12. As in the embodiment shown in Fig. 1 the O-rings 17 and 18 prevent metallic contact between the stub 11 and the nipple 12. Also, oscillations emanating from the magnetic valve are almost completely damped.

In the embodiment shown in Fig. 3, a packet of rings, in which the O-rings 17 and 18 are guided or clamped in by rings 25 and 26 preferably comprising synthetic material, is arranged between the shoulder 20 of the nipple 12 and the shoulder 24 of the stub 11. The synthetic material rings are either formed to be relatively resilient in order to prevent the transmission of oscillations or they are appropriately larger in internal diameter than the diameter of the widening 19 of the bore 16.

In the embodiment shown in Fig. 4, the stub 11 and the nipple 12 are similar to those shown in Fig. 3.

However, the packet comprises rings of different kinds of material. The first ring 28 bearing against the shoulder 24 acts as stuffing box ring which is axially compressed and resistant to high temperatures. Following this ring is an O-ring 17, which is followed by an asbestos string ring 29, which is either encased in soft metal or wound around by Teflon yarn. Following this asbestos string ring 29 is a synthetic material ring 30, which melts at higher temperatures and thereby impregnates the asbestos string ring so that a good fuel seal is provided. The entire packet can be loaded by a spring 32 through a washer 31 in order to obtain good axial pressing for the stuffing box ring 28. The ring combination may be chosen differently, it being important that no metallic contact exists between nipple 12 and stub 11 with an optimum of outflow safety.

In the embodiment shown in Fig. 5, the stub 11 has two steps 14 and 15 similar to those shown in the first embodiment. Provided between both these steps is a conical section 33, opposite which is a cone 34 in the bore 16. A rhombic cross-section spacer ring 35 of resilient material is provided between both these conical surfaces. This ring 35 takes over the centering of the stub 11 in the nipple 12, while the O-rings 17 and 18 take over the sealing.

As shown in Fig. 6, this ring 38 may be provided with recesses 36 running in the longitudinal direction or with other kinds of hollow spaces in order to give the ring a higher resilience.

At least one of the rings may be so sprayed onto the valve or metallised as to remain on the valve por tion on removal of the connecting element.

The above described embodiments of the present invention have the advantage that no oscillations are any longer transferred to the pressure duct and that a high degree of safety is attained thereby, apart from the appreciable noise reduction.

Claims

1. A fuel injection apparatus for an internal combustion engine, comprising a valve, a fuel duct connecting element pluggable over a portion of the valve, and at least one resilient sealing ring so disposed between said portion of the valve and the connecting element as to prevent metallic contact axially and radially of the valve portion between the latter and the connecting element.

2. An apparatus as claimed in claim 1, wherein the valve is a magnetic valve.

3. An apparatus as claimed in either claim 1 or claim 2, comprising two sealing rings located at an axial spacing from each other.

4. An apparatus as claimed in claim 3, comprising shoulders between which at least one of the rings is so located as to limit the axial extentto which the connecting element is pluggable over the valve.

5. An apparatus as claimed in either claim 3 or claim 4, comprising groove means by which the sealing rings are located.

6. An apparatus as claimed in either claim 3 or claim 4, comprising steps by which the sealing rings are located.

7. An apparatus as claimed in any one of claims 3 to 6, comprising at least one spacer ring to located the sealing rings.

8. An apparatus as claimed in claim 7, wherein the at least one spacer ring comprises synthetic material.

9. An apparatus as claimed in either claim 7 or claim 8, wherein the or at least one of the spacer rings is a stuffing box ring.

10. An apparatus as claimed in any one of claims 7 to 9, further comprising an asbestos ring.

11. An apparatus as claimed in any one of claims 7 to 10, wherein all the rings are axially loadable.

12. An apparatus as claimed in either claim 10 or claim 11, wherein the ring which comprises synthetic material has a low melting point and is disposed adjacent the asbestos ring.

13. An apparatus as claimed in any one of the preceding claims, wherein the valve and the connec ting element are each provided with frusto-conical surface portions which face each other at a spacing, a ring having a rhombic cross-section in a plane con taining the axis of the ring being so disposed between the faces as to absorb forces axially and radially of the valve portion.

14. An apparatus as claimed in clairn 13, wherein the rhombic ring is provided with recesses to increase its resilience.

15. An apparatus as claimed in claim 13, wherein the rhombic ring is provided with hollow spaces to increase its resilience.

16. An apparatus as claimed in any one of the preceding claims, wherein the valve portion is provided with at least one annular groove in which a respective ring is so disposed as to remain on the valve portion on removal of the connecting element from the valve portion.

17. An apparatus as claimed in any one of the preceding claims, where at least one of the rings has been so metallised as to remain on the valve portion on removal of the connecting element from the valve portion.

18. An apparatus as claimed in any one of the preceding claims, wherein at least one of the rings has been so glued on the valve portion as to remain on the valve portion on removal of the connecting element from the valve portion.

19. A fuel injection apparatus substantially as hereinbefore described with reference to Fig. 1 of the accompanying drawings.

20. An apparatus as claimed in claim 19 and modified substantially as hereinbefore described with reference to Fig. 2 of the accompanying drawings.

21. An apparatus as claimed in claim 19 and modified substantially as hereinbefore described with reference to Fig. 3 of the accompanying drawings.

22. An apparatus as claimed in claim 19 and modified substantially as hereinbefore described with reference to Fig. 4 of the accompanying drawings.

23. An apparatus as claimed in claim 19 and modified substantially as hereinbefore described with reference to Fig. 5 of the accompanying drawings.

24. An apparatus as claimed in claim 19 and modified substantially as hereinbefore described with reference to Fig. 6 of the accompanying drawings.