Injector and method for injecting fuel and an additional fluid

Abstract

An injector (1) for injecting fuel and an additional fluid, is provided in that the injector (1) is designed for optimal space-saving yet exhibiting a simple construction. This construction results in a precise injection of a fuel and an additional fluid into a combustion chamber of an internal combustion engine. The arrangement has two solenoid valves, the first valve (2) and the second valve (3). The second solenoid valve (3) has a second nozzle needle (9) which is arranged in the injector (1), and the first nozzle needle (7) of the first solenoid valve (2) and the second nozzle needle (9) of the second solenoid valve (3) are arranged one behind the other on a longitudinal axis (10) of the injector (1). Further, the nozzle needles (7, 9) can be controlled independently of one another.

Claims

1. An injector (1) for injecting fuel and an additional fluid into a combustion chamber of an internal combustion engine, the injector (1) comprising: a first solenoid valve (2) with a first nozzle needle (7) for delivery of an additional fluid, and a second solenoid valve (3) with a second nozzle needle (9) for delivery of a fuel arranged in the injector (1), that the first nozzle needle (7) of the first solenoid valve (2) and the second nozzle needle (9) of the second solenoid valve (3) are arranged on a longitudinal axis (10) of the injector (1) one behind the other; the second nozzle needle (9) of the second solenoid valve (3) is arranged between the first nozzle needle (7) and the combustion chamber of the internal combustion engine on the longitudinal axis (10) of the injector (1); wherein injection into the combustion chamber of the additional fluid precedes that of the fuel.

2. The injector (1) according to claim 1, wherein the second nozzle needle (9) has a longitudinal bore.

3. The injector (1) according to claim 2, wherein the second nozzle needle (9) has a plurality of outlet openings (27) connected to the longitudinal bore.

4. The injector (1) according to claim 1, wherein the injector has a three-part housing which is secured with a first union nut (16) and a second union nut (17).

5. The injector (1) according to claim 1, further comprising a first holder (21) with a first magnetic coil (6) and a second holder (23) with a second magnetic coil (8) are arranged on the injector (1).

6. A method for injecting fuel and an additional fluid into a combustion chamber of an internal combustion engine using an injector (1), comprising the steps of: providing a first solenoid valve (2) with a first nozzle needle (7) for injecting an additional fluid into the combustion chamber, and providing a second solenoid valve (3) with a second nozzle needle (9) in the injector (1) for injecting a fuel into the combustion chamber, wherein the first nozzle needle (7) of the first solenoid valve (2) and the second nozzle needle (9) of the second solenoid valve (3) are arranged one behind the other on a longitudinal axis (10) of the injector (1), and the nozzle needles (7, 9) are controlled independently of one another; wherein the first solenoid valve (2) injects a metered quantity of the additional fluid and the second solenoid valve (3) injects a metered quantity of the fuel into the combustion chamber of the internal combustion engine; wherein injection into the combustion chamber of the additional fluid metered by the first solenoid valve (2) precedes injection of the fuel metered by the second solenoid valve (3).

7. The method according to claim 6, wherein the additional fluid metered by the first solenoid valve (2) is injected into the combustion chamber guided through a longitudinal bore provided in the second nozzle needle (9).

8. The method according to claim 7, wherein the additional fluid injected into the combustion chamber is distributed by several outlet openings (27) provided at an end of the second nozzle needle (9) and connected to the longitudinal bore.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) FIG. 1: an injector according to the invention for injecting fuel and an additional fluid,

(2) FIG. 2: a view of several outlet openings in a nozzle needle of the injector according to the invention,

(3) FIG. 3 an illustration of several injection phases that can be handled by the injector according to the invention in an internal combustion engine with a preceding water injection, and

(4) FIGS. 4a to 4d illustrations of different phases of the operation of an internal combustion engine with a preceding water injection into a combustion chamber.

(5) FIG. 1 shows an injector 1 according to the invention for injecting fuel and an additional fluid. Water is described below as an example of such an additional fluid.

DETAILED DESCRIPTION OF THE INVENTION

(6) According to the invention, the injector 1 according to the invention includes a first solenoid valve 2 and a second solenoid valve 3.

(7) The first solenoid valve 2 is used to inject or meter the additional fluid water, which is supplied to the injector 1 via the first connection 4. The second solenoid valve 3 is provided for injecting or metering a fuel which is supplied to the injector 1 via a second connection 5. Both the fuel and the additional fluid can be supplied to the injector 1 with a corresponding applied pressure.

(8) The first solenoid valve 2 has a first solenoid 6 and a first nozzle needle 7, with the first nozzle needle 7 being guided and supported in a corresponding guide within the injector 1.

(9) The second solenoid valve 3 has a second solenoid 8 and a second nozzle needle 9, wherein the second nozzle needle 9 is also guided and supported in a corresponding guide within the injector 1.

(10) The injector 1 according to the invention hence has two fluid paths that can be controlled independently of one another. Thus, with the injector 1, both a fuel and an additional fluid water can be appropriately metered independently of one another and introduced or injected into a combustion chamber of an internal combustion engine in a timed manner.

(11) The first connection 4 for supplying an additional fluid is arranged, for example, in a region of the longitudinal axis 10 of the injector 1. This may be the end of the injector which faces away from the combustion chamber (not shown), when the injector 1 is in operation.

(12) The injector 1 is designed with a second connection 5 for supplying a fuel in a lateral region of the injector 1. This second connection 5 can for example be attached in a central area of the outer wall of the injector 1, wherein the second connection 5 may be oriented at an angle with respect to the longitudinal axis. An exemplary arrangement of the second connection 5 is shown in FIG. 1.

(13) Such an angle can be in the range between 15° and 75° with respect to the longitudinal axis 10 of the injector 1, preferably at an angle of 45° with respect to the longitudinal axis 10 of the injector 1.

(14) The first nozzle needle 7, through which the additional fluid water flows, can be opened by activating the first magnetic coil 6 of the first magnetic valve 2. Without this electrical control, the for example conical tip of the first nozzle needle 7 is pressed by a first spring 11 against a likewise conically terminated water chamber 12 that is connected to the first connection 4 and thus closed. This first nozzle needle 7 is aligned along a longitudinal axis 10 of the injector.

(15) The second nozzle needle 9 of the second solenoid valve 3 is also aligned on the longitudinal axis 10 of the injector 1, with the second nozzle needle 9 being arranged in the injector 1 in the region of the longitudinal axis 10 between the first nozzle needle 7 and the combustion chamber.

(16) The second nozzle needle 9 has a longitudinal bore arranged, for example, in the center and along the longitudinal axis 10. This longitudinal bore allows the additional fluid water exiting from the first solenoid valve 2 to reach the combustion chamber of the internal combustion engine. Thus, the first solenoid valve 2 is able to inject a metered quantity of an additional fluid, such as water, into the combustion chamber, regardless of the operation of the second solenoid valve 3.

(17) An additional fluid is introduced into an additional fluid chamber 12 inside the injector 1 via the first connection 4. This chamber 12 is closed by the first nozzle needle 7. Via the second connection 5, a pressurized fuel is introduced into a fuel chamber 13 of the injector 1, which is closed by the second nozzle needle 9. Such chambers 12 and 13 for storing fuel or an additional fluid offer the advantage of compensating for pressure fluctuations which can occur during ongoing operation of the internal combustion engine.

(18) Activating the second solenoid 8 of the second solenoid valve 3 opens the second nozzle needle 9, enabling fuel to be injected from the fuel chamber 13 of the injector 1 through the nozzle 14 at the tip of the second nozzle needle 9 into the combustion chamber of the internal combustion engine.

(19) Without this electrical control, the for example conical tip of the second nozzle needle 9 of the second solenoid valve 3 is pressed by a second spring 15 against a likewise conically terminated fuel outlet nozzle 14 of the injector 1 and is thus closed.

(20) In this exemplary embodiment of the invention, the first nozzle needle 7 moves away from the combustion chamber in order to open the opening for injecting an additional fluid, as indicated in FIG. 1 by the arrow in the first nozzle needle 7.

(21) In this exemplary embodiment of the invention, the second nozzle needle 9 must move towards the combustion chamber in order to open the opening for injecting fuel into the combustion chamber of the internal combustion engine, as indicated in FIG. 1 by the arrow in the second nozzle needle 9.

(22) The housing of the injector 1 can, for example, be constructed in three parts from three housing parts and, when assembled, form a cylindrical body with a base body 18. To affix the three housing parts of the injector to one another, a first union nut 16 and a second union nut 17 are arranged at the ends of the injector 1. Such a construction enables a simple assembly of the injector 1 and provides good mechanical stability.

(23) For example, a positioning bolt 19 ensures that the fuel bores in the lower and middle housing part are axially aligned with one another when the injector 1 is assembled.

(24) As is known in the art, the first spring 11 and the second spring 15 each produce a corresponding restoring force, which returns the first nozzle needle 7 and the second nozzle needle 9 to their respective starting positions, after the magnetic forces of the first magnetic coil 6 and the second magnetic coil 8 have been removed. A stuffing box 20, on which the first spring 11 is supported, is provided for suitably positioning the first spring 11 so that it can fulfill its function. This is necessary because this first spring 11 is arranged in an inflow channel between the first connection 4 and the first nozzle needle 7 or the additional fluid chamber 12.

(25) To ensure a simple assembly of the injector 1, the lower, second nozzle needle 9 is composed of several parts. For this purpose, the second nozzle needle 9 may, for example, have a thread onto which an anchor can be screwed. The position of this anchor can be secured, for example, with a lock nut or an alternative fastening element.

(26) In the region of the first solenoid valve 2, the injector 1 has a first holder 21 which receives the first solenoid 6 and a functionally associated first iron ring 22. The holder 21 also has an electrical connection for connecting the first magnetic coil 6, for example, to a control device (not shown).

(27) In the region of the second solenoid valve 3, the injector 1 has a second holder 23 which receives the second solenoid 8 and a functionally associated second iron ring 24. The second holder 23 also has an electrical connection for connecting the second magnetic coil 8 to the control device.

(28) Corresponding seals 25 and 26 are provided to seal the supply lines (not shown) for the first connection 4 and for the second connection 5.

(29) The injector 1 according to the invention enables a fuel and an additional fluid, such as water, to be injected independently of one another. To control the injector 1, a control unit and conventional systems for supplying a fuel or an additional fluid may be provided. As is customary, the fuel and the additional fluid may be supplied to the injector 1 under pressure.

(30) FIG. 2 shows a view of several outlet openings 27 in the second nozzle needle 9 of the injector 1 according to the invention. The second nozzle needle 9, which has a centrally arranged longitudinal bore, can be designed with a fully continuous longitudinal bore.

(31) In an alternative embodiment, the end of the second nozzle needle 9 pointing into the combustion chamber of an internal combustion engine may not be designed to terminate with a central longitudinal bore. For an improved spatial distribution of an additionally injected fluid, the end of the second nozzle needle 9 may have several outlet openings 29 which are not arranged in the area of the longitudinal axis 10.

(32) These outlet openings 29 may have a smaller diameter than the longitudinal bore and may be arranged, for example, on a circle around the longitudinal axis 10.

(33) In the illustration of FIG. 2, the longitudinal bore is designed as a countersunk bore that is connected to six outlet openings 29. These six outlet openings 29 may be arranged at the end of the second nozzle needle 9 in such a way that their respective longitudinal axes intersect with the longitudinal axis 10 of the second nozzle needle 9. The respective longitudinal axes of the six outlet openings 29 are thus arranged at an angle with respect to the longitudinal axis 10, which may for example be between 15° and 55°. The design of the end of the second nozzle needle 9 is shown here as an example and does not represent a limitation of this design.

(34) FIG. 3 shows a diagram of several injection phases that can be handled by means of the injector 1 according to the invention in an internal combustion engine with an upstream water injection.

(35) The diagram shows as an example a curve depicting the distance between the piston and top dead center as a function of the angle of the crankshaft.

(36) As shown, for example, an additional fluid, such as water, is injected into a combustion chamber in a range between 360° and 330°, which can be implemented by the first solenoid valve 2 of the injector 1 according to the invention.

(37) Also shown is a first injection of a fuel in the range between 330° and 270° and a second injection in a range between 270° and 210°, which can be implemented by the second solenoid valve 3 of the injector 1 according to the invention.

(38) This example only serves to illustrate the effort involved in determining optimal parameter combinations, wherein three injection times with their respective mass proportions and pressures have to be coordinated with one another, as well as the possible uses of the injector 1 according to the invention.

(39) The injector according to the invention may advantageously also be used to generate a locally different composition of the fuel-air mixture, i.e. a charge stratification, in the combustion chamber of the internal combustion engine. The article “Upstream fuel quantity with stratified diesel-water injection”, MTZ 01/2007, year 68, Vieweg Verlag, is hereby representative as a source describing the state of the art.

(40) In an early intake phase, a water injection can precede the fuel injection, as is shown in FIG. 4a. This water injection is performed with the first solenoid valve 2. An insulating vapor layer is formed as a result of the evaporation of the water injected into the hot combustion chamber of the internal combustion engine.

(41) The fuel is then injected into this insulating vapor layer with the second solenoid valve 3. The resulting fuel-air mixture is now surrounded or enveloped by the insulating vapor layer. The formation of the desired vapor layer around the fuel-air mixture in an intake phase is shown in FIG. 4b.

(42) In the expansion phase following this intake phase, the insulating vapor layer keeps enveloping the fuel-air mixture, as shown in FIG. 4c.

(43) At the time of the combustion of the fuel-air mixture in the combustion chamber of the internal combustion engine, the insulating vapor layer forms an insulating layer towards the cylinder wall and the piston. This combustion process is shown in FIG. 4d. The formation of this insulation layer reduces the wall heat losses of the cylinder walls.

LIST OF REFERENCE SYMBOLS

(44) 1 injector 2 first solenoid valve 3 second solenoid valve 4 first connection (additional fluid/water) 5 second connection (fuel) 6 first solenoid 7 first nozzle needle 8 second solenoid 9 second nozzle needle 10 longitudinal axis 11 first spring 12 additional fluid chamber (water chamber) 13 fuel chamber 14 nozzle 15 second spring 16 first union nut 17 second union nut 18 base body 19 positioning bolt 20 stuffing box 21 first holder 22 first iron ring 23 second holder 24 second iron ring 25 first seal 26 second seal 27 outlet opening