GB2096702A - Fuel injection valves for internal combustion engines - Google Patents

Abstract

A valve member (6) which opens the valve in the direction of flow of the fuel and is rotatably mounted by means of a ball bearing (14), has passage portions (21b), tangential to a circle (K) concentric with the valve axis, whose outlet ports (22) are covered by the valve body (3) in the rest position. When the valve is opened by fuel pressure, the outlet ports (22) emerge from the bore (5), and the discharge of fuel causes the valve member to rotate, whereby the emerging fuel describes a helical spraying pattern. <IMAGE>

Description

SPECIFICATION Fuel injection valves for internal combustion engines The invention relates to fuel injection valves for internal combustion engines.

In a known injection valve, the valve needle is guided by a valve body, for movement in the direction of fuel flow through the body, so that, under fuel pressure, it partly projects out of the valve body partially or fully uncovering fuel outlet ports located in the circumference of the projecting or bottom end of the needle. The fuel sprayed out of the ports can thus be regulated and apportioned. The stream of fuel which is sprayed through the respective outlet port has to swing from an initially roughly vertical direction into a roughly horizontal direction, that is to say, it follows a sweeping course, from the beginning of fuel flow to the time of complete uncovering of the outlet ports. The resultant spraying cone provides good spreading and good mixing of the fuel with the combustion air and therefore more rapid ignition and combustion, can be expected.As the fuel apportioned by the injection pump passes in a pressure wave to the injection valve, the valve needle is suddenly thrust out of the bore in the valve body. The outlet ports are therefore completely released for a short while, before the actual spraying procedure, with its sweeping course, begins. If only a small quantity of fuel is supplied, as is the case especially during idling, the sudden opening of the ports results in the fuel being sprayed only in one direction.

It is an object of this invention to provide an improved fuel injection valve.

From one aspect the invention consists in a fuel injection valve for an internal combustion engine, comprising a valve body, a fuel inlet, a valve needle rotatably mounted in the body for movement in the direction of fuel flow through the valve, bias means for urging the needle into a rest position, the needle having fuel outlet ports which are closed by the valve body in a rest position and which are at least partially released when the needle is moved. under the fuel pressure, the outlet ports being formed in the circumferential surface of the needle and being connected to the fuel inlet by fuel paths, the outlet end sections of which are formed in the needle and run roughly tangentially to a circle, which is concentric to the central axis of the valve needle.

Thus the valve needle can be made to rotate by the fuel which is flowing through the passages or paths and hence it is possible for the fuel which is sprayed from the fuel outlet ports to describe a helical spraying pattern. This helical spraying pattern produces an especially wide-reaching atomization and distribution of the fuel in the combustion chamber. The mixing which is obtained is generally independent of the quantity of fuel which is fed in, as the outlet ports are completely released for only a short time by the conventional pressure wave, which acts on the valve needle, and the ports introduce the injection procedure, even with small quantities of fuel.The fuel which describes a helical spraying pattern may also start the combustion air in the combustion chamber rotating, as a result of which, as a especial advantage, the twisted inlet passages, which have previously been provided to swirl the inlet air, become unnecessary. The fuel which is being injected can, however, also sustain an existing rotating movement of the combustion air.

It will be appreciated that when larger quantities of fuel are fed in, after the introductory pressure wave, the injection procedure continues, so that the helical spraying pattern is amplified by the known sweeping course which occurs as a result of the controlled opening of the outlet ports. The combustion chamber is consequently completely smeared by the fuel which is being injected. The extraordinarily good atomization and spreading in the combustion chamber which may result from the fuel injection nozzle according to the invention contributes very considerably to better utilization and combustion of the fuel. The rotation of the valve needle is induced by the reaction forces acting on the needle which occur when the fuel is sprayed from the roughly tangential passages or paths, i.e. the paths or passages are directed to induce a tangential component force on the fuel.

The tangential passages in the valve needle may run at a slant towards the bottom or outlet end of the valve needle. This enables the fuel to penetrate more accurately into the heart of the combustion air when the fuel outlet ports are released.

The fuel injection valve may furthermore be so designed that the valve needle has a thickened end which cooperates with a valve seat located in the valve body upstream of the outlet ports, the passages originating from a point on the outer surface of the thickened end which is situated in a space which is positioned downstream of the valve seat between the thickened end of the valve needle and the bore in the valve body. With this arrangement a seal is formed upstream and consequently a satisfactory division is produced between the part of the fuel injection valve which is in communication with the fuel supply and the part which is in communication with the combustion chamber, hence avoiding any possible sucking off of fuel from the gap between the valve needle and the conveyance of it in the valve body, which might, for example, result in uncontrolled ignition and HC emissions.Moreover, this valve seat may enable the exact determination of the beginning and the end of the injection procedure, because the passages are actuated only after the valve needle has been raised by the fuel. As the valve needle rotates during spraying and the fuel outlet ports are covered in the rest position, undesirable carbonization of the bottom end of the valve needle can be prevented.

The space situated downstream of the valve seat, the purpose of which is to distribute the fuel evenly to the passages immediately after the valve needle is raised from the valve seat, can be formed by an annular groove located in the valve needle and/or the valve body.

In order to obtain easy rotation of the valve needle, the valve needle can be mounted so as to rotate relative to the valve body by means of a roller bearing.

The invention may be performed in various ways, a specific embodiment of which, will now be described with reference to the accompanying drawings, in which: Figure 1 shows a longitudinal section through a part of a fuel injection valve; Figure 2 shows a part of the valve needle of the valve of Figure 1 on an enlarged scale; and Figure 3 shows a view of the valve needle in the direction of the arrow A in Figure 2.

A fuel injection valve which is partly illustrated in Figure 1 has a valve support 1, to which a valve body 3 is fastened by means of a screw cap 2. The valve body 3 has an axial through-bore 4 and a cylindrical bore 5, which is connected coaxially to the bore 4 at its bottom end and has a larger diameter, for receiving a valve needle 6. The valve needle 6, is mounted for axial and rotational movement in the valve body 3 by means of a pistonlike section 7 located in the bore 5 and by means of a cylindrical section 8 at the top end of its shaft 9. A valve seat 10 is disposed between the bore 5 and the bore 4. A conical shoulder 11 abuts against the seat 1 0 under the force of a spring 12 which acts on the needle 6.The spring 12 acts between the valve body 3 and a spring plate 13, which is connected to the shaft 9 of the valve needle 6 via an axial ball bearing 14 and a pressure disc 1 5.

The valve support 1 is also provided with a passage 16, which is connected to an injection pump (not shown). This passage 1 6 opens into a chamber 17, in which the spring 12 is located and into which the valve body 3 projects. By means of a cross-bore 18 Icoated in the valve body 3, the chamber 17 is in communication with a tubular interspace 19, which lies between the shaft 9 and the bore 4 and extends from the cylindrical section 8 to the shoulder 11 or the valve seat 10. An annular space constituted by an annular groove 20 is formed in the valve body 3, downstream of the valve seat 10.Passages 21 which are located in the pistonlike section 7 of the valve needle 6, extend from the annular space to outlet ports 22 which lie on the circumferential surface of the pistonlike section 7 and which are covered by the surface of the bore 5 of the valve body 3 in the rest position which is shown.

As can be seen from Figures 2 and 3, three passages 21 are, for example, provided in the pistonlike section 7 of the valve needle 6. Each of these passages 21 begins in a groove 23 in the section 7 which faces the annular groove 20. Each passage 21 initially runs in a first section 21 a radially and downwardly at a slant at an angle , of for example 60 , relative to the central axis of the valve needle. The three sections 21 a of the passages 21 intersect on the central axis of the valve needle 6. After they intersect the sections 21 a extend as far as an imaginary circle K, which is concentric to the central axis of the valve needle 6 and is indicated in dots and dashes.

Conveniently the diameter of the circle K is, for example, approximately half the outside diameter of the pistonlike section 7. From this circle K, the passages in a second section 21 b run tangentially and at an angle P of approximately 60O downwardly at a slant -- relative to the needle axis - to the outlet ports 22 which are situated on the circumferential surface of the pistonlike section 7.

The fuel, which is fed under pressure into the passage 16 of the fuel injection valve, passes through the chamber 1 7 and the cross-bores 1 8 into the interspace 1 9 and exerts a force on the cross-section of the shoulder 11, which is upstream of the valve seat 1 0, which exceeds the force of the spring 12, so that the valve needle 6 is raised, from the valve seat 10, downwardly in the direction of flow of the fuel. It will be seen that the fuel pressure becomes effective directly over the entire surface of the shoulder 1 The fuel then passes into the space formed by the annular groove 20 and/or the groove 23, and from this into the passages 21.The extent by which valve needle 6 is raised, and hence the extent by which the outlet ports 22 are uncovered is determined by the magnitude of the fuel pressure of the quantity of fuel apprbpriate to the load. The reaction force of the fuel emerging through the tangential passages 21 out of the outlet ports 22 induces the valve needle 6 to rotate by means of the axial ball bearing 1 4, in the direction of the arrow D so that the fuel - as partly indicated in Figure 3 - is sprayed in a helical spraying pattern. At the same time, the fuel which emerges through the outlet ports 22 -- depending to what extent the outlet ports 22 are released -- is swung from an almost vertical direction indicated by the line B into the direction indicated by the line C, which corresponds roughly to the direction of the passages 21 in their second section 21 B. As soon as the fuel supply is discontinued, the valve needle 6 comes back into abutment against the valve seat 1 0 under the action of the spring 1 2. As a result the outlet ports 22 are covered by the bore 5 and sucking off of fuel from the passages 21 is consequently prevented.

Claims (5)

1. A fuel injection valve for an internal combustion engine, comprising a valve body, a fuel inlet, a valve needle rotatably mounted in the body for movement in the direction of fuel flow through the valve, bias means for urging the needle into a rest position, the needle having fuel outlet ports which are closed by the valve body in a rest position and which are at least partially released when the needle is moved under the fuel pressure, the outlet ports being formed in the circumferential surface of the needle and being connected to the fuel inlet by fuel paths, the outlet end sections of which are formed in the needle and run roughly tangentially to a circle, which is concentric to the central axis of the valve needle.

2. Afuel injection valve as claimed in claim 1, wherein the tangential end sections in the valve needle run at a slant towards the outlet end of the valve needle.

3. A fuel injection valve as claimed in claim 1 or claim 2, wherein the valve needle has a thickened portion, which cooperates with a valve seat which is located on the valve body up-stream of the outlet ports and wherein each path is constituted by a passage which originates from a point on the outer surface of the thickened portion which is situated in a space, which is downstream of the valve seat, between the thickened end of the valve needle and the valve body.

4. A fuel injection valve as claimed in claim 3, wherein the space is formed by an annular groove which is located in the thickened end of the valve needle and/or in a bore of the valve body.

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