Injection device for an internal combustion engine

Abstract

The invention relates to an injection device for an internal combustion engine, comprising a needle and an armature, which is operatively connected to the needle in such a way that a movement of the needle can be produced by movement of the armature, the armature having at least one passage bore, through which fuel can be conducted to a needle tip, characterized in that a longitudinal axis of the needle and a longitudinal axis of the passage bore are oriented askew in relation to each other.

Claims

1. An injection device for an internal combustion engine, the injection device comprising: a fuel injection housing having a fuel outlet via which fuel is injected into an air admixing chamber or a combustion chamber; a needle having a tip that abuts the injection housing at the fuel outlet; and an armature operatively connected to the needle such that the needle is movable by way of the armature, wherein the armature has at least one passage bore through which fuel is conducted to the needle tip, wherein a longitudinal axis of the needle and a longitudinal axis of the passage bore are in a skewed orientation relative to one another such that fuel conducted through the passage bore causes the armature and the needle to rotate about the longitudinal axis of the needle as the needle tip abuts the injection housing at the fuel outlet, and wherein the needle is provided in a centrally arranged bore of the armature.

2. The injection device as claimed in claim 1, wherein the passage bore comprises an inlet opening and an outlet opening in the armature, and wherein a distance between the inlet opening and the longitudinal axis of the needle is smaller than a distance between the outlet opening and the longitudinal axis of the needle.

3. The injection device as claimed in claim 1, wherein the injection device is in the form of a coil-type injector.

4. The injection device as claimed in claim 1, wherein the armature has a multiplicity of passage bores which are arranged radially on a circular path around a centrally situated longitudinal axis of the needle, wherein the longitudinal axis of the passage bore encloses an acute angle with a tangential plane of the circular path.

5. The injection device as claimed in claim 2, wherein the armature has a multiplicity of passage bores which are arranged radially on a circular path around a centrally situated longitudinal axis of the needle, wherein the longitudinal axis of the passage bore encloses an acute angle with a tangential plane of the circular path.

6. The injection device as claimed in claim 3, wherein the armature has a multiplicity of passage bores which are arranged radially on a circular path around a centrally situated longitudinal axis of the needle, wherein the longitudinal axis of the passage bore encloses an acute angle with a tangential plane of the circular path.

7. The injection device as claimed in claim 4, wherein the acute angle lies in the range of ±45°.

8. The injection device as claimed in claim 7, wherein the acute angle lies in the range of ±30°.

9. The injection device as claimed in claim 8 wherein the acute angle lies in the range of ±15°.

10. The injection device as claimed in claim 5, wherein the acute angle lies in the range of ±45°.

11. The injection device as claimed in claim 10, wherein the acute angle lies in the range of ±30°.

12. The injection device as claimed in claim 11, wherein the acute angle lies in the range of ±15°.

13. An injection device for an internal combustion engine, the injection device comprising: a needle having a tip that abuts an injection device housing at a fuel outlet of the housing; and an armature which is operatively connected to the needle such that a movement of the needle can be generated by way of a movement of the armature, wherein the armature has at least one passage bore through which fuel can be conducted to a needle tip, and wherein a longitudinal axis of the needle and a longitudinal axis of the passage bore are in a skewed orientation relative to one another, wherein the passage bore comprises an inlet opening and an outlet opening in the armature, and wherein a distance between the inlet opening and the longitudinal axis of the needle is smaller than a distance between the outlet opening and the longitudinal axis of the needle.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1 depicts a sectional view of the basic construction of a known injection device along the section plane A-A of FIG. 2;

(2) FIG. 2 depicts a sectional view of the known injection device of FIG. 1 along the section plane B-B from FIG. 1;

(3) FIG. 3 depicts a sectional view, along the section plane C-C of FIG. 4, of an injection device configured in accordance with the principles of the invention; and

(4) FIG. 4 depicts a sectional view, along the section plane D-D of FIG. 3, of an injection device configured in accordance with the principles of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

(5) The invention will be explained below on the basis of the description of the figures. The claims, the figures and the description contain a multiplicity of features which will be explained below in conjunction with embodiments of the present invention described by way of example. A person skilled in the art will also consider said features individually and in other combinations to form further embodiments which are adapted to corresponding uses of the invention.

(6) The basic construction of a known injection device will be explained on the basis of FIG. 1. The injection device 10 has a housing 15 in which an armature 13 is provided. The armature 13 comprises a central bore 13a through which a needle 11 is guided. The needle 11 has stops 12a and 12b and a needle tip 11a, which in FIG. 1 is illustrated at the lower end of the needle 11. In the housing 15 there are provided outlet openings 18 via which fuel is delivered out of the interior of the housing 15 when the needle 11 is situated in an open position.

(7) For the actuation of the injection device 10, that is to say for the transfer of the needle 11 from a closed position into an open position, a coil 16 is energized. Said coil generates a magnetic field which is boosted by the cores 17. This causes the armature 13 to be attracted upward along the double arrow F in FIG. 1. During said movement, the armature 13 comes into contact with the upper stop element 12a and drives the needle 11 along with it. The upward movement of the needle 11 and of the armature 13 is stopped when the armature 13 comes into contact with the core 17. Alternatively, other suitable stop elements may be provided for stopping the movement of the armature 13. To transfer the needle 11 into its closed position again, the energization of the coil 16 is stopped, and the magnetic field is thus eliminated. The spring 19 then exerts a spring force on the upper stop element 12a and thus pushes the needle 11 into the closed position. In this case, the needle tip 11a abuts against the housing 15 in the regions denoted by the letter E in FIG. 1. A substantially annular sealing surface is formed between the needle tip 11a and the housing 15.

(8) As an alternative to the embodiment illustrated, the spring 19 may also act directly on the armature 13. In this case, the armature 13 moves downward and comes into contact with the lower stop element 12b. As a result, the armature 13, during its movement, drives the needle 11 along with it and transfers the latter into the closed position.

(9) The path of the fuel will be described below. The fuel is conducted through the opening 21 from a fuel line (not illustrated) into the chamber 20 with the aid of a fuel delivery pump. From the central chamber 20, the fuel passes via the throughflow bores 14a, 14b into the tapering region below the armature 13. The delivery pump generates a corresponding pressure in the region that is flooded with fuel. When the needle 11 is transferred into an open position, the pressure prevailing in the chamber 20 causes the fuel to flow through the outlet openings 18 into a combustion chamber or into an intake tract of the internal combustion engine.

(10) In the process, a flow is generated in which fuel flows from the chamber 20 through the inlet opening into the passage bore 14a, 14b and through the outlet opening from the passage bore into the region below the armature 13. FIG. 1 is a sectional illustration of the injection device along the section plane A-A from FIG. 2, and FIG. 2 is a sectional view along the section plane B-B from FIG. 1.

(11) As can be seen from FIGS. 1 and 2, in the prior art, the throughflow bores 14a, 14b are oriented such that their axial directions are oriented parallel to a central axis H of the needle 11 or of the central bore 13a.

(12) On this basis, the invention will now be explained on the basis of FIGS. 3 and 4, with the same reference signs as those used in FIGS. 1 and 2 being used to designate identical components. FIG. 3 is a sectional view along the section plane C-C, in which the longitudinal axis I of the passage bore 14a also lies, from FIG. 4. As can be seen from this, the passage bore 14a runs obliquely through the armature 13. In other words, according to the invention, the axial direction, that is to say the longitudinal axis I of the throughflow bore 14a is skewed in relation to the longitudinal axis H which runs through the center of the needle 11. In this case, the longitudinal axis H simultaneously constitutes the central axis of the central bore 13a, through which the needle 11 runs, in the armature 13. That is to say, the inlet opening of the throughflow bore 14a, which in FIG. 3 is depicted in the upper region of the armature 13, is situated closer to the longitudinal axis H than the outlet opening of the throughflow bore 14a, which is depicted in FIG. 3 in the lower region of the armature 13. The distance a between the inlet opening and the central axis H is thus smaller than the distance b between the outlet opening of the throughflow bore 14a and the central axis H. The distances a and b are measured from the central point of the inlet opening from the central point of the outlet opening, respectively, to the central axis H. An outlet opening is illustrated in FIG. 4 by the dashed circle with a central point M.sub.A.

(13) For better explanation of the present geometrical situation, FIG. 4 illustrates a particularly preferred embodiment of the invention. This has a multiplicity of throughflow bores 14a, 14b, wherein the inlet openings are all arranged on a circular path K, the central point of which lies on the longitudinal axis H of the needle 11. The longitudinal axis I of the throughflow bore 14a runs in the section plane C-C which is oriented parallel to the longitudinal axis H of the needle 11. The section plane C-C and consequently also the longitudinal axis I of the throughflow bore enclose an angle a with a tangential plane T which runs tangentially with respect to the circular path K and which intersects the plane C-C at the central point ME of the inlet openings of the passage bore 14a. Said angle a lies in the range of ±45°, preferably in the range of ±30° and particularly preferably in the range of ±15°, in relation to the tangential plane T. That is to say, the angle of the longitudinal axis I of the passage bore 14a may deviate from the tangential plane T for example by +15° or by −15°.

(14) The mode of operation of the present invention will be briefly described below on the basis of FIGS. 3 and 4. The fuel, that is to say substantially diesel or gasoline, is conducted via a fuel line into the chamber 20, as also described with reference to FIG. 1, fills the passage bore 14a, and the tapering region situated below the armature 13, and is present therein in a pressurized state. By means of a coil 16, a magnetic field is generated with the aid of the core 17, which magnetic field sets the armature 13 in motion. In this case, the armature 13 moves upward along the double arrow F. When the outlet openings permit a throughflow, fuel is conducted through the throughflow bores 14a, 14b, wherein, when the fuel emerges from the passage bores 14a, 14b, said fuel emerges from the throughflow bore 14a not in the axial direction of the needle 11 but in a direction that is skewed in relation thereto. This causes a torque to be imparted to the armature 13, whereby the latter is set in a rotational motion about its vertical axis H. Since the armature 13 is in contact with the upper stop element 12a, the rotational movement is also transmitted to the needle 11.

(15) The fuel flows out of the common chamber 20 through the throughflow bores 14a, 14b into the tapering region below the armature 13, flows past the needle tip 11a, and emerges from the injection device 10 through the outlet openings 18 (not illustrated in FIG. 3). In this case, a rotational movement of the armature 13 is permanently generated, and thus a rotational movement of the needle 11 is also permanently generated. When the needle 11 is transferred from an open position into a closed position, the rotational movement continues, owing to the mass inertia, until the moment at which the needle tip 11a bears against the inner housing 5. Said rotational movement is stopped at the time at which the needle tip abuts against the region E in the interior of the housing 15. In this way, the sealing surface or the sealing region E is cleaned of contaminants every time it is abutted against by the needle 11.

(16) The foregoing disclosure has been set forth merely to illustrate the invention and is not intended to be limiting. Since modifications of the disclosed embodiments incorporating the spirit and substance of the invention may occur to persons skilled in the art, the invention should be construed to include everything within the scope of the appended claims and equivalents thereof.