DE102005000853A1 - Gasket extrusion detecting method for use in injector, involves detecting existence of incorrect, large gasket extrusion in injector using measured recycle flow of injector, where measured flow is larger than preset recycle flow - Google Patents

Abstract

The method involves operating an internal combustion engine (7) with low load and less speed, and measuring a recycle flow of an injector (1), where the flow is correlated with an injector stroke. The existence of incorrect, large gasket extrusion in the injector is detected using the measured flow, where the measured flow is larger than a preset marginal recycle flow correlated with the injector stroke. An independent claim is also included for a measuring container for measuring recycle flow in an injector of a fuel injection device of an internal combustion engine in a motor vehicle.

Description

The The present invention relates to a method for detecting a Sealing ring extrusion in an injector of a fuel injection device an internal combustion engine, in particular in a motor vehicle.

injectors of fuel injectors, in particular as common-rail injection systems can be designed contain at least one nozzle needle, which performs strokes for controlling fuel injection, hereinafter also referred to as Injektorhübe be designated. The operation of the injectors can lead to signs of wear. Are susceptible to wear on the one hand sealing rings, which in the injector a low-pressure area of separate a high pressure area. Due to the extremely high pressures in the high pressure area can it come to these sealing rings to extrusion phenomena, through which the sealing rings are more or less leaking. Of Further, a valve piston that moves with each injector stroke, wear out. The valve piston also separates the low pressure area inside the injector from the high pressure area. Dependent on the valve piston wear comes It therefore also to a greater or lesser leakage along the valve piston.

So long the leakage due to sealing ring extrusion and valve piston wear small are, thereby resulting in no disadvantages to the functionality of the injector. Because the injector is suitably constructed so that leaks on the sealing ring and the valve piston in a return area reach, in the also a tax amount for driving the nozzle needle and design-related leaks occur. One from the return area dissipated Return quantity is thus composed of a tax amount and a leakage together. The leakage can on the one hand the construction-related leaks and on the other caused by wear Leaks over include the sealing ring and the valve piston.

increasing Wear on Sealing ring and the valve piston leads thus to an increase in leakage and ultimately to an increase the return amount. By measuring the return flow can thus be determined whether a permissible high wear exists. However, it can not be distinguished whether the increased return amount due a sealing ring extrusion or due to valve piston wear occurs. The distinction between sealing ring extrusion and valve piston wear can so far only be done by the respective injector from the internal combustion engine expanded and disassembled into its individual parts. Only then can sealing ring and valve piston closer be examined to determine the respective cause of leakage can.

It is however of increased Interest, between leakage due to sealing ring extrusion and a leakage due to valve piston wear differ to be able to. Because while the injector remains functional for a relatively long time in the case of a valve spool wear, a sealing ring extrusion can increase comparatively quickly and subsequently inadmissible lead to high leakage. An excessive return flow however, may cause malfunction lead the internal combustion engine.

Advantages of invention

The present invention having the features of the independent claims In contrast, the Advantage that without disassembly of the injector from the internal combustion engine and without disassembly of the injector can be determined whether a Sealing ring extrusion is present or not. This may increase the risk of excessive return flow be reduced by replacing the relevant injector. Furthermore can the maintenance costs for the fuel injector can be lowered considerably, since only those injectors must be replaced, in which a sealing ring extrusion is present.

The On the one hand, the invention is based on the recognition that the composition the return amount From control quantity, construction-related leakage and wear-related Leakage (valve piston wear and Sealing ring extrusion) depending of the load state of the internal combustion engine changes. On the other hand, the Invention also on the finding that caused by valve piston wear additional Leakage quantity with increasing valve piston wear via a certain limit value does not go, provided the internal combustion engine operated at low load and / or at low speed. In contrast, the leakage amount due to seal extrusion is strong from the respective degree of wear dependent. Accordingly, the present invention recognizes an impermissibly large seal ring extrusion then if the measured return flow is larger as a predetermined limit return amount, the above limit for the condition caused by valve piston wear Leakage amount considered.

Preferably the measurement of the return flow takes place at an idling operation of the internal combustion engine, since there both a low load as well as a low speed.

In a particularly advantageous Ausfüh In the form of an injection, it is also possible to detect the presence of an impermissibly large spool wear due to the fact that the measured return flow is smaller than the limit retrace flow and, moreover, is greater than a predetermined tolerance retrace flow. This tolerance return amount is composed of the control amount and the design-related leakage together and can also be provided with a tolerance factor to account for tolerance-related fluctuations in the return flow in a new or wear-free injector and tolerable wear phenomena. With the help of the method according to the invention can thus be detected without disassembly, whether the respective injector is wear-free within the tolerance or whether he has impermissible sealing ring extrusion and / or impermissible valve piston wear. Depending on the detected or undetected errors or signs of wear, a suitable maintenance measure can then be initiated.

Appropriately the method can be realized by the respective injector instead of a return hose a measuring vessel connected is used, with the help of which the return amount especially easy to measure. During the measuring operation of the Internal combustion engine collects the return flow in the measuring vessel and can be measured there accordingly.

The Invention is thus also based on the idea of creating a measuring vessel, that instead of a return hose connectable to an injector is and with its help the return flow of the respective injector can be measured particularly easily.

Further important features and advantages of the invention will become apparent from the Dependent claims, from the drawing and the associated Description of the figures with reference to the drawing.

drawing

embodiments The present invention are shown in the drawing and will be closer in the following explained.

The only 1 shows a highly simplified longitudinal section through an injector of a fuel injector.

description the embodiments

Corresponding 1 includes an injector 1 a high pressure connection 2 , a control signal terminal 3 , a return port 4 , an injector body 5 and a nozzle needle 6 , The injector 1 forms part of a fuel injection device of an internal combustion engine only indicated here 7 , in particular in a motor vehicle. When assembled, the injector is 1 like here with his injector body 5 in the internal combustion engine 7 used.

In operation, the injector 1 over the high pressure connection 2 supplied with high-pressure fuel. In a so-called common-rail system are several injectors 1 over their respective high-pressure connection 2 connected to a common high-pressure fuel line.

To the return connection 4 In operation, a return hose is connected, via which a return flow from the injector 1 removed and expediently supplied to a fuel tank. To carry out the method according to the invention, instead of the return hose according to 1 a measuring vessel 8th to the return port 4 of the injector 1 be connected. This measuring vessel 8th For this purpose, for example, has a connection piece 9 which, like the return hose, complements the return port 4 is designed. In this way, the measuring vessel 8th with a connecting piece 9 on the return connection 4 of the injector 1 be plugged. Preferably, the connection piece 9 also with a seal 10 be equipped to prevent leakage when measuring the return flow.

Preferably, the measuring vessel 8th transparent and with a scale 11 provided, which facilitates the reading of the return amount.

While the high pressure connection 2 with a high pressure area 12 of the injector 1 communicates, is the return port 4 with a low pressure area 13 of the injector 1 connected. To the injector body 5 the high pressure area 12 from the low pressure area 13 to separate, on the one hand a valve piston 14 provided, together with the nozzle needle 6 stroke adjustable in the injector body 5 is stored. This valve piston 14 on the one hand is the high pressure area 12 and on the other hand the low pressure area 13 exposed. Furthermore, the valve piston 14 in a sleeve 15 axially guided and stored. The dimensions of sleeve 15 and valve piston 14 are coordinated so that at least in new condition despite the large pressure difference between the high pressure area 12 and low pressure area 13 no or only a minimal, tolerated leakage occurs along the axial guidance. The resulting leakage quantity is due to the design and is via the return, so through the return port 4 , dissipated.

The sleeve 15 is in the injector body 5 firmly inserted, being between sleeve 15 and injector body 5 at least one sealing ring 16 is arranged, which thus also the high pressure area 12 from the low pressure area 13 separates.

Via the control signal connection 3 is in operation of the injector 1 an electrically actuated actuator 17 triggered to raise or lower the nozzle needle 6 to effect.

In operation of the injector 1 falls during each injection process to a return flow, which is at least for servo-operated nozzle needles 6 composed of a control amount and a design-related leakage amount. The return flow is via the return connection 4 dissipated. With every injection process, the nozzle needle leads 6 an opening stroke and a closing stroke, which is also referred to below as injector.

In operation of the injector 1 It may come due to the high-frequency injector strokes to wear. Relevant in the present context on the one hand a valve piston wear, which is characterized by an increasing leakage along the valve piston 14 characterized. On the other hand, the high-frequency pressure pulsations can also lead to an extrusion of the sealing ring 16 to lead. This sealing ring extrusion also has an increasing leakage over the sealing ring 16 result. Due to the design, the wear-related leaks flow into the low-pressure area 13 and thereby increase the return amount. In order to be able to determine whether an inadmissible large wear in the injector 1 is present, and to distinguish in particular between a sealing ring extrusion and a valve piston wear reliable, the inventive method can now be carried out as follows:
The internal combustion engine 7 is operated at low load and / or low speed. In this case, an operation of the internal combustion engine is preferred 7 idle. In the low load range or idle, a return flow of the respective injector 1 measured, this return amount is correlated with the Injektorhub. This amount of return, correlated with the injector stroke, is suitably related to the injector stroke. For example, a return amount per injector stroke is determined.

The measurement of the return flow is expediently carried out with the aid of the measuring vessel 8th , which instead of a return hose to the return port 4 of the injector 1 connected. For measuring the return amount, the internal combustion engine 7 be operated at idle, for example, a predetermined time. The amount of reflux occurring during this time can be measured at the measuring vessel 8th be read particularly easily. About the known speed of the internal combustion engine 7 at idle and on the number of cylinders and number of cycles of the internal combustion engine 7 It is particularly easy to determine the return flow per injector stroke.

By Compare the measured return flow with a predetermined limit return amount correlated with the injector stroke can now be recognized whether an impermissibly large sealing ring extrusion is present or not. Is the measured return flow greater than the predetermined limit return amount, is an inadmissible size Sealing ring extrusion before. If the measured return flow is smaller than the predetermined limit return quantity, there is no seal ring extrusion or is the seal ring extrusion still in a tolerable range.

The limit return flow rate is defined so that it corresponds to a return amount that occurs when the sealing ring is intact and at maximum valve piston wear when the internal combustion engine 7 at low load and / or low speed, preferably at idle, is operated. The determination of the limit return flow rate is thus based on the knowledge that the leakage has a maximum at idling due to valve piston wear, and from this maximum is independent of the wear. Thus, if the measured return flow is greater than the limit return flow rate thus defined, then it can only be seal ring extrusion.

Of Furthermore, the presence of an impermissibly large valve piston wear can also be detected in the injector become. This is done by the measured return flow although smaller than the limit return quantity, however, it is bigger as a predetermined tolerance return amount correlated with the injector stroke. This tolerance return amount can For example, be set so that when a new injector the return quantity, resulting from the amount of tax and from construction and in particular the rail pressure or engine load dependent leaks is multiplied by a tolerance factor that is for a fluctuation of the return flow due to manufacturing tolerances and on the other uncritical signs of wear tolerated. As long as the measured return amount related to the injector stroke less than the mentioned tolerance return amount, can not be more serious Valve spool wear is present. In practice, the tolerance return amount be about half the size like the limit return amount.

The particular advantage of the method according to the invention is seen in that without disassembly of the injector 1 from the internal combustion engine 7 and without disassembly of the injector 1 It can be recognized whether a seal ring extrusion is present or not. As a result, maintenance work can be particularly cost-effective by using only those injectors 1 be replaced, in which a sealing ring extrusion has been found.

1

injector

2

High pressure port

3

Control signal terminal

4

Return connection

5

injector

6

nozzle needle

7

Internal combustion engine

8th

measuring Cup

9

spigot

10

poetry

11

scale

12

High pressure area

13

Low pressure area

14

plunger

15

shell

16

seal

17

actuator

Claims (12)

Method for detecting a seal ring extrusion in an injector ( 1 ) a fuel injection device of an internal combustion engine ( 7 ), in particular in a motor vehicle, - in which the internal combustion engine ( 7 ) operated at low load and / or at low speed and a correlated with an injector stroke return flow of each injector ( 1 ) is detected, - in which the presence of an impermissibly large sealing ring extrusion is detected by the fact that the measured return amount is greater than a predetermined, correlated with the Injektorhub limit return amount. Method according to Claim 1, characterized in that the internal combustion engine ( 7 ) when measuring the return flow at idle. Method according to claim 1 or 2, characterized in that at the injector ( 1 ) the presence of an impermissibly large valve piston wear is detected by the fact that the measured return quantity is smaller than the limit return quantity and is greater than a predetermined tolerance return quantity correlated with the injector stroke. Method according to claim 3, characterized that the tolerance return amount about half as big like the limit return amount. Method according to claim 3 or 4, characterized that the tolerance return amount is through a control quantity correlated with the injector stroke and one with the Injector stroke correlated tolerable amount of leakage is formed. Method according to one of claims 1 to 5, characterized that the limit return amount by the amount of return occurring at maximum valve piston wear is determined. Method according to one of claims 1 to 6, characterized in that the return amount is measured by the fact that to the respective injector ( 1 ) instead of a return hose, a measuring vessel ( 8th ) is connected. Method according to claim 7, characterized in that the measuring vessel ( 8th ) a connecting piece ( 9 ), which is complementary to a provided for connecting the return hose return port ( 4 ) of the injector ( 1 ) is designed so that the measuring vessel ( 8th ) on the injector ( 1 ) can be plugged. Measuring vessel for measuring a return flow in an injector ( 1 ) a fuel injection device of an internal combustion engine ( 7 ), in particular in a motor vehicle, which is designed such that instead of a return hose to the injector ( 7 ) is connectable. Measuring vessel according to claim 9, characterized in that the measuring vessel ( 8th ) a connecting piece ( 9 ), which is complementary to a provided for connecting the return hose return port ( 4 ) of the injector ( 1 ) is designed so that the measuring vessel ( 3 ) on the injector ( 1 ) can be plugged. Measuring vessel according to claim 10, characterized in that the connecting piece ( 9 ) a seal ( 10 ) having. Measuring vessel according to one of claims 9 to 11, characterized in that the measuring vessel ( 8th ) is transparent and with a scale ( 11 ) is provided for reading the return amount.