EP1876349B1

EP1876349B1 - Method for calibrating an injector

Info

Publication number: EP1876349B1
Application number: EP06014132.2A
Authority: EP
Inventors: Marco Siringo
Original assignee: Continental Automotive GmbH
Current assignee: Continental Automotive GmbH
Priority date: 2006-07-07
Filing date: 2006-07-07
Publication date: 2016-05-18
Anticipated expiration: 2026-07-07
Also published as: EP1876349A1

Description

The invention relates to calibrate an injector with an injector assembly. The injector assembly comprises a double-tube-shaped fluid pipe and an injector cover. The injector cover has a fluid connection of the injector and a fluid line of the injector cover. The fluid line of the injector cover communicates with the fluid connection of the injector. The injector cover is at least partly arranged in the double-tube-shaped fluid pipe.
Modern internal combustion engines often are designed very compact. In such internal combustion engines there is not much space for components, for example an injection valve, of the internal combustion engine. So, the injection valve has to be designed very compact. However, the injection valve has to be connected to a fuel connection and an electrical or hydraulic circuit for driving an actor of the injection valve. Further, such an injection valve has to be calibrated. In general, the two connections and means for calibrating the injection valve are very space consuming.
DE 199 32 760 A1 discloses a fuel injection valve designed to be mounted in the fuel injection system for an internal combustion engine. The fuel injection valve comprises a piezoelectric or magnetostrictive actuator mounted in a valve body sealingly protected against the fuel by an actor housing. The valve body and the actor housing have adjacent recesses. The valve body is coupled to the actor housing in a marginal zone of the recesses. Thus a communicating orifice is formed sealed against the fuel. The communicating orifice is filled with a filler element whereto at least an electric supply of the actuator is fixed inside said communicating orifice.
WO 2005/026558 A1 discloses a hydraulic system comprising a housing and a compensation reservoir. The compensation reservoir has an elastic sleeve and a storage volume. The elastic sleeve embraces the housing including the storage volume. The storage volume is sealed from the exterior by the elastic sleeve. The storage volume is hydraulically linked with an interior space of the hydraulic system. A dilatation of the elastic sleeve caused by a hydraulic pressure on the surface facing the housing results in an expansion of the storage volume which in turn allows the storage volume to receive an excess volume of a fluid from the interior space of the hydraulic system.
EP 1 548 854 A1 discloses an actuator unit comprising a tube spring, a piezoelectric actuator that is inserted into the tube spring, a first cap that is connected to the tube spring in a first free end of the tube spring and which is adjoined by the piezoelectric actuator. A tube-shaped body is connected to the tube spring by joining and is arranged in the area of the second free end of the tube spring. Pretensioning means are arranged for pretensioning the piezoelectric actuator.
EP 1593841 A1 discloses a fuel injection valve with an actuator and a hydraulic coupler being arranged in a valve housing. The hydraulic coupler includes a cylinder in which an axially movable coupler is arranged with a coupler gap between the piston and the cylinder. An adjusting device is attached within an adjusting channel of the valve housing, and acts on the hydraulic coupler to set a predetermined coupler gap. Adjustment of the coupler gap is effected after sealing of the valve housing with the housing covers.
It is an object of the invention to create a method for calibrating a compact injector which easily enables a proper fluid injection characteristic of the injector.
The object is achieved by the independent claim 1. Advantageous embodiments of the invention are given in the subclaims.
An injector assembly for an injector comprises a double-tube-shaped fluid pipe and an injector cover. The injector cover has a fluid connection of the injector and a fluid line of the injector cover. The fluid line of the injector cover communicates with the fluid connection of the injector. The injector cover is at least partly arranged in the double-tube-shaped fluid pipe. The injector cover and the double-tube-shaped fluid pipe are formed and arranged such that the relative axial position of the injector cover to the double-tube-shaped fluid pipe influences a.fluid injection characteristic of the injector. The method comprises varying the relative axial position of the injector cover to the double-tube-shaped fluid pipe until the fluid injection characteristic of the injector corresponds to a given fluid injection characteristic.
The injector assembly enables to create the injector fairly compact because the injector cover fulfills three different tasks: sealing up the inside of the injector, embodying the fluid connection, and enabling the calibration of the injector through its axial position relative to the double-tube-shaped fluid pipe. The fluid injection characteristic may comprise, for example, a spray shape of the injected fluid, an average drop size, an amount of injected fluid in a given time etc.
In an advantageous embodiment of the invention, the injector cover has at least a first and a second axial section. The first axial section has a larger diameter than the second axial section of the injector cover. The fluid connection of the injector is formed at the first axial section of the injector cover facing away from the second axial section of the injector cover. This contributes to that the injector cover fulfills the three tasks in a simple way.
In a further advantageous embodiment, the double-tube-shaped fluid pipe comprises an electrical connection path which penetrates the double-tube-shaped fluid pipe at least partly radially. This contributes very effectively to the compactness of the injector.
In a further advantageous embodiment, the double-tube-shaped fluid pipe has an outer tube and an inner tube for guiding the fluid between the outer and the inner tube of the double-tube-shaped fluid pipe. The outer tube of the double-tube-shaped fluid pipe is radially coupled to the first axial section of the injector cover. The inner tube of the double-tube-shaped fluid pipe is radially coupled to the second axial section of the injector cover. The double-tube-shaped fluid pipe communicates with the fluid line of the injector cover. The coupling of the first axial section with the outer tube enables the sealing of the inside of the injector against the environment. The coupling of the second axial section to the inner tube enables the sealing of the inside of the inner tube against the fluid.
The invention is explained in the following with the help of schematic drawings.
These are as follows:

figure 1: an injector,
figure 2: an injector assembly for the injector,
figure 3: a cut through the injector assembly according to figure 2.

Elements with the same design and function that appear in different illustrations are identified by the same reference characters.
An injector 2 (figure 1) has a valve body 4 and a needle 6. The needle 6 is arranged in a recess 8 of the valve body 4. The needle 6 is movable in axial direction. A first spring 10 forces the needle 6 via a spring washer 12 towards an actor 14 of the injector 2.
The actor 14 comprises a ground plate 16 and a top plate 18. Preferably, the actor 14 is a piezoelectric actuator. The actor 14 is axially coupled to a hydraulic compensation device 20 at the top plate 18 of the actor 14. There may be arranged a second spring which is axially coupled to the hydraulic compensation device 20 facing away from the actor 14. In an alternative embodiment the hydraulic compensation device may be arranged between the spring washer 12 and the ground plate 16 of the actor 14.
Further, the injector 2 comprises an injector assembly (figure 2). The injector assembly comprises a double-tube-shaped fluid pipe 21 and an injector cover 24. The double-tube-shaped fluid pipe 21 comprises an inner tube 22 and an outer tube 23. A fluid, preferably fuel, is guided to an injection nozzle in a free volume between the inner tube 22 and the outer tube 23 of the double-tube-shaped fluid pipe 21. The injection nozzle is formed by the valve body 4 and the needle 6, if the needle 6 is outside of its closing position. In the closing position of the needle 6 the needle 6 and the valve body 4 prevent a fluid flow by closing the injection nozzle.
The injector cover 24 sealingly covers the injector. The injector cover 24 preferably comprises a first axial section 26 and a second axial section 28. The diameter of the first axial section 26 is larger than the diameter of the second axial section 28. The first axial section 26 is radially coupled to the outer tube 23. The second axial section 28 is radially coupled to the inner tube 22. A fluid connection 30 of the injector is arranged at the first axial section 26 facing away from the second axial section 28. A fluid line 32 of the injector cover 24 communicates with the fluid connection 30 and with the double-tube-shaped fluid pipe 21.
The fluid connection 30 is arranged for connecting the injector 2, for example, to an.external fluid line. The injector cover 24 preferably is welded at the first axial section 26 to the outer tube 23. The fluid connection 30 of the injector and the fluid line 32 of the injector cover 24 preferably are produced by drilling two simple holes into the injector cover 24.
Preferably, an O-ring 34 is arranged between the second axial section 28 and the inner tube 22, for sealing up the inside of the double-tube-shaped fluid pipe 21 against the fluid,
The actor 14 is connected to an electric circuit. If the actor 14 gets energized, the injector 14 increases its axial length in some microseconds. If the actor 14 increases its length in such a fast way, the hydraulic compensation device 20 reacts like a stiff body. So, the ground plate 16 of the injector 14 forces the needle 6 away from the compensation device 20. If the force of the actor 14 on the needle 6 is the same or bigger than the force of the first spring 10 on the needle 6, the needle 6 moves away from its closing position and away from the hydraulic compensation device 20. Then, the injection nozzle is formed at the tips of the valve body 4 and the needle 6. In this way, the fluid flow through the injection nozzle is enabled. If the injector 2 gets deenergized again, the actor 14 decreases its length in some microseconds and the needle 6 closes the injection nozzle. So, the fluid flow through the injection nozzle is prevented.
If the relative position of the actor 14 to the double-tube-shaped fluid pipe 21 changes slowly, for example, because of a thermal expansion and a different thermal expansion coefficient of the actor 14 and the double-tube-shaped fluid pipe 21, the hydraulic compensation device 20 compensates that thermal expansion.
Because of the actor 14, the hydraulic compensation device 20 and system tolerances of the whole injector 2, the injector 2 has to be calibrated. For calibrating the injector 2, the injector cover 24 is at least partially arranged in the double-tube-shaped fluid pipe 21. The hydraulic compensation device 20 is coupled to the actor 14 and the actor 14 is coupled to the spring washer 12 and the needle 6. The injector cover 24 gets pressed towards the actor 14 with a given force. Then, fluid is injected through the injector 2 and the force on the injector cover 24, and in particular the relative axial position of the injector cover 24 to the double-tube-shaped fluid pipe is varied until the fluid injection characteristic of the injector 2 corresponds to a given fluid injection characteristic. Then, the force is held and the injector cover 24 is welded to the outer tube 23.
Alternatively, the injector 2 may be calibrated by forming a threat on the injector cover 24 and a corresponding threat on the double-tube-shaped fluid pipe 21. Then, the injector cover 24 may be screwed onto the double-tube-shaped fluid pipe 21. Then, while screwing the injector cover 24 to the double-tube-shaped fluid pipe 21, fluid is injected by the injector 2. If the fluid injection characteristic corresponds to the given fluid injection characteristic, the screwing is stopped.
So, the relative axial position of the injector cover 24 to the double-tube-shaped fluid pipe 21 influences the fluid injection characteristic of the injector 2. The fluid injection characteristic may comprise a spray shape of the injected fluid, an amount of injected fluid in a given time and/or with a given fluid pressure, an average drop size, an average drop range etc.
In this way, the injector cover 24 fulfills three different tasks: sealingly covering up the injector 2, forming the fluid connection of the injector 2, and enabling the calibration of the injector 2. This is very space saving because instead of the injector cover 24, normally, there would have to be three different components for fulfilling the three different tasks.
In this context, it is very advantageous if the injector assembly comprises an electrical connection path 36 (figure 3). The electrical connection path 36 penetrates the double-tube-shaped fluid pipe 21. The electrical connection path 36 extends at least partly radially. The electrical connection path 36 is arranged for the electrical contact of the actor 14 to the electrical circuit. The electrical connection path 36 is sealed against the double-tube-shaped fluid pipe 21.
The invention is not restricted on the explained embodiments. For example, the injector cover 24 may comprise more axial sections. Further, the fluid connection 30 may be not arranged parallel to an axis of the injector 2 and/or not in an overlapping area with the axis of the injector 2. Further, there may be arranged further O-rings for sealing up the injector 2.

Claims

Method for calibrating an injector (2),
the injector (2) comprising an injector assembly and an actor (14), the injector assembly comprising a double-tube-shaped fluid pipe (21) and an injector cover (24) having a fluid connection (30) of the injector (2) and having a fluid line (32) of the injector cover (24) which communicates with the fluid connection (30) of the injector (2), the injector cover (24) being at least partly arranged in the double-tube-shaped fluid pipe (21), being characterized in that the injector cover (24) and the double-tube-shaped fluid pipe (21) are formed and arranged such that the relative axial position of the injector cover (24) to the double-tube-shaped fluid pipe (21) influences a fluid injection characteristic of the injector (2),
the method comprising varying the relative axial position of the injector cover (24) to the double-tube-shaped fluid pipe (21) until the fluid injection characteristic of the injector (2) corresponds to a given fluid injection characteristic.
The method in accordance with claim 1, wherein the injector cover (24) is pressed towards the actor (14) with a given force and the force is varied for varying the axial position.
The method in accordance with claim 2, further comprising holding the force when the fluid injection characteristic of the injector (2) corresponds to the given fluid injection characteristic and welding the injector cover (24) to an outer tube (23) of the double-tube-shaped fluid pipe (21).
The method in accordance with claim 1, wherein the injector cover (24) is screwed onto the double-tube shaped fluid pipe (21) until the fluid injection characteristic of the injector (2) corresponds to the given fluid injection characteristic.
The method in accordance with one of the preceding claims, wherein the injector cover (24) has at least a first and a second axial section (26, 28), the first axial section (26) having a larger diameter than the second axial section (28) of the injector cover (24) and wherein the fluid connection (30) of the injector (2) is formed at the first axial section (26) of the injector cover (24) facing away from the second axial section (28) of the injector cover (24).
The method in accordance with one of the preceding claims, wherein the double-tube-shaped fluid pipe (21) comprises an electrical connector path (36) which penetrates the double-tube-shaped fluid pipe (21) at least partly radially.
The method in accordance with one of the preceding claims, wherein
- the double-tube-shaped fluid pipe (21) has an outer tube (23) and an inner tube (22) for guiding the fluid between the outer and the inner tube (23, 22) of the double-tube-shaped fluid pipe (21),

- the outer tube (23) of the double-tube-shaped fluid pipe (21) is radially coupled to the first axial section (26) of the injector cover (24),

- the inner tube (22) of the double-tube-shaped fluid pipe (21) is radially coupled to the second axial section (28) of the injector cover (24),

- the double-tube-shaped fluid pipe (21) communicates with the fluid line (32) of the injector cover (24).
The method in accordance with one of the preceding claims, wherein the injector assembly comprises an O-ring (34) which is arranged between the second axial section (28) of the injector cover (24) and the inner tube (22) of the double-tube-shaped fluid pipe (21) for sealing up an inside of the inner tube (22) against the fluid.