GB2062753A

GB2062753A - Fuel Injection Nozzle for Internal Combustion Engines

Info

Publication number: GB2062753A
Application number: GB8034708A
Authority: GB
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1979-10-30
Filing date: 1980-10-29
Publication date: 1981-05-28
Also published as: IT1134017B; JPS5675959A; DE2943744A1; FR2468759A1; JPH0154552B2; GB2062753B; DE2943744C2; FR2468759B1; IT8025551A0

Abstract

The nozzle holder inlet receiving the fuel supply pipe sealing cone 14 has a first portion 17 of 60 DEG cone angle, corresponding to the pipe cone, and a second portion 19 of 90 DEG cone angle. The portion 19 permits the delivery passage 12 to be drilled at a greater angle to the holder axis whereby the length of the holder may be reduced. <IMAGE>

Description

SPECIFICATION Fuel Injection Nozzle for Internal Combustion Engines The invention relates to a fuel injection nozzle for internal combustion engines.

In tapered sealing seats, provided by inner and outer cones in such nozzles, the sealing pressure depends on the taper angle and on the force with which the outer cone is pressed against the inner cone. In practice, an angle of 600 has been commonly adopted. The taper of the angular bore of the pressure channel which normally branches off from a blind bore adjacent to the inner cone, is determined by the depth and also the cone angle, since the sealing cone must not be damaged during the drilling of this angular bore. In known fuel injection nozzles the nozzle-holder portion, between the compartment containing the spring to load the nozzle needle and the pressure connection is therefore relatively long.This fact is contrary to the requirements of the engine manufacturer who aims to minimise the length of the fuel injection nozzle, since, in the development of modern motor vehicles, and for a variety of reasons, such as the reduction in weight of auxiliary appliances, little space is available under the radiator bonnet. An important factor influencing overall length, however, is the angular bore, whose angular disposition, as mentioned above, is determined by the taper angle, which in its turn influences the tightness of seal and therefore cannot be of such a magnitude as might be desirable so far as the angular bore is concerned.

According to the present invention in a fuel injection nozzle for internal combustion engines comprising a nozzle holder, at the end remote from the injection end of which there is provided an axially extending pressure connection having a terminal inner cone to which an outer cone of the delivery line is clamped by means of a cap nut applied to the nozzle holder, and from which there branches a pressure channel for by-passing a compartment containing the spring for loading the nozzle needle, the pressure channel comprising two bores, namely, an angular bore which branches from a blind bore adjacent to the inner cone and leads to the region of the rim of the nozzle holder, and a bore which is connected to the angular bore, extends parallel to the spring compartment, and which terminates at the end face of the nozzle holder, the inner cone is constructed as a double cone comprising a first conical section having a taper angle corresponding to that of the outer cone and a second, outwardly-adjacent conical section of wider taper angle.

In contrast to the known art the fuel injection nozzle of the present invention has the advantage that, owing to the wider-angled outer cone, the angular bore can be arranged at a relatively oblique angle, and that also, because of reduced overlapping of the outer and inner cone surfaces, an increased surface pressure, and consequently increased seal, are achieved. Because of the provision of the double cone and the essential short portion of the bore in which the further cone section terminates, the outer cone of the delivery line is more deeply embedded in the pressureconnection member of the nozzle holder, so that the cap nut meshes via an additional number of screw threads with the nozzle holder. Apart from the desired reduction in the overall length of the injection nozzle, an improved seal and greater security against loosening of the pressure connection are achieved.

The invention will now be further described by way of example with reference to and as illustrated in the accompanying drawing, the single Figure of which shows, in vertical section, a fuel injection nozzle according to the invention.

In the fuel injection nozzle shown in the drawing, a nozzle body (not shown) is clamped by means of a clamping nut 1 to a nozzle holder 3, an intermediate plate 2 being inserted between the clamping nut and the forward end of the nozzle holder. The nozzle body receives a nozzle needle 4, which is spring-loaded by a closure spring 6 via a spring disc 5. The closure spring 6 is arranged in a spring compartment 7, which is pressure-baianced via a bore 8 and a largerdiameter bore 9 connected thereto and leading to an overflow-oil hose connection nipple 10.The pressure chamber (not shown) arranged between the valve needle 4 and the nozzle body is supplied with fuel via a delivery line 11, an angular bore 12 which branches from a blind bore (described hereinafter) adjacent an inner cone and extends to the region of the rim of the nozzle holder, and a bore 1 3 extending parallel to and by-passing the spring compartment 7. Bones 12 and 13 constitute a pressure channel from delivery line 11 to the nozzle body. The delivery line 11 is fixedly connected to an outer cone member 14, which is clamped to an inner double cone 17, 19 by means of a cup nut 16 which meshes with a screw thread 1 5 on the rear end of the nozzle holder 3. The outer cone 14 and a first section 1 7 of the inner cone both have a taper angle of 600.

Between the shouider of the cone member 14 and the cap nut 16 there is arranged a clamping ring 1 8. Adjacent to the first section 1 7 of the inner cone in a direction towards the delivery line 11 is a second section 1 9 of the inner cone having a larger taper angle. Adjacent to this larger taper angle cone 19 is a cylindrical portion 20, which also helps to reduce the length of the injection nozzle. Adjacent to the inner cone section 1 7 in a direction towards the spring compartment is a cylindrical blind bore 21, from whose countersunk base 22 the angular bore 12 branches eccentrically. The broken line 23 shows that, during boring, no contact takes place with either of the surfaces of the double cone 17, 1 9 nor with the surface of the cylindrical portion 20.

If, however, the inner cone section 1 7 were to be outwardly extended, the periphery of the drill coincident with line 23 and the generating line of the cone section 17 would intersect at the point 24.

Claims

1. A fuel injection nozzle for internal combustion engines, comprising a nozzle holder.

at the end remote from the Injection end of which there is provided an axially extending pressure connection having a terminal inner cone to which an outer cone of the delivery line is clamped by means of a cap nut applied to the nozzle holder, and from which there branches a pressure channel for by-passing a compartment containing the spring for loading the nozzle needle, the pressure channel comprising two bores, namely, an angular bore which branches from a blind bore adjacent to the inner cone and leads to the region of the rim of the nozzle holder, and a bore which is connected to the angular bore, extends parallel to the spring compartment, and which terminates at the end face of the nozzle holder, wherein the inner cone is constructed as a double cone comprising a first conical section having a taper angle corresponding to that of the outer cone and a second, outwardly-adjacent conical section of wider taper angle.

2. A fuel injection nozzle as claimed in claim 1,, wherein the second conical section forms an angle of 900, whilst that of the first conical section forms an angle of 600.

3. A fuel injection nozzle as claimed in claim 1 or 2, wherein approximately half of the outer cone is in contact with the inner cone first conical section of the double cone.

4. A fuel injection nozzle substantially as herein described with reference to and as illustrated in the accompanying drawing.