Title of Invention	PROCESS AND DEVICE FOR LEAKAGE-TESTING OF A FUEL-INJECTION VALVE OF AN INTERNAL COMBUSTION ENGINE (IC-ENGINE)
Abstract	The invention relates to a method and device for leak-proofing a fuel injection valve for an internal combustion engine, wherein the inventive method consists in determining a temperature quantity characterising the temperature of at least one part of said fuel injection valve and in concluding the presence of a leakage on the basis of said temperature quantity.

Full Text

Process and Device for Leakage-Testing of a Fuel-Injection Valve of an Internal Combustion Engine (IC-engine) State of the art of technology The invention relates to a process and a device for leakage-testing of a fuel-injection valve of an IC-engine with an actuator, through which a connection of the fuel-injection valve with a high-pressure fuel-source is controlled, at least indirectly through an electrical control-unit, according to the generic descriptions of the independent claims. In motor vehicles with an IC-engine the fuel is pumped or conveyed with the help of a fuel-pump from a fuel-tank and is fed to the fuel-injection valves, which is also known as injectors, via fuel-pipelines. Excess fuel usually reaches back to the fuel-tank through a return pipeline. IC-engines with high-pressure injection, especially in IC-engines with self-ignition, an additional pump gets itself attached to the fuel pump, which generates a very high pressure in a high-pressure segment, also known as Rail, which remains connected to the injectors. In such fuel-supply systems there is a risk of a leak in the high-pressure segment, with the result that fuel gets into the return-pipeline. This is usually known as inner leakage. Moreover, an outward leakage is also possible, in which case fuel under high pressure gets into the engine compartment. An enhanced leakage leads to a permanent deviation in the rail-pressure. This can lead to a defect/failure of the IC-engine. From the Patent Document DE 197 03 891 Al a process and a device to detect leakage in a fuel-supply-system of an IC-engine, especially an IC-engine with a Common-Rail-System is known, where a pressure sensor detects or compiles the pressure in the high-pressure segment. In this context at least two pressure parameters at different time-points are recorded, from these two pressure parameters a fuel-mass-balance is prepared, where, proceeding from the fuel-mass-balance the existence of an error/fault is concluded. With such a process and such an instrument a leakage indeed generally can be identified, but it is not possible to recognize a cylinder-specific leakage in this way. In the event of a leakage, the exchange of all injectors is necessary, although, for example, only one injector has a leakage. This is not only disadvantageous from a cost point-of-view, but also the exchange of all injectors requires also a substantial assembly effort. Only for workshop purposes an injector-individual or injector-specific leakage measurement with a small measuring tube at the injector is also known, which is however only used with passenger automobiles and is moreover not accepted by all car-manufacturers, since the leakage measuring requires dealing with fuel at a running engine in an open atmosphere, which represents a substantial safety risk. The invention is therefore based on the task, to design a process and a device for leakage-testing of a fuel-injection-valve of an IC-engine, through which in a simple and secure way it can be identified, whether an individual injector has a leakage. Advantages of the Invention This task is solved with the initially described process and device for leakage-testing of a fuel-injection valve of an IC-engine with the characteristics of the Claims 1 and 9. The invention uses the empirically found knowledge that a leakage heavily heats up the injector-body including its attached parts. Basic idea of the invention is therefore, to compile a temperature-parameter, which characterizes the temperature of at least one part of the fuel-injector valve and to trace the existence of a leak based on such an input. As temperature-parameter, the temperature can be measured directly with a sensor. Especially advantageous is to derive the temperature-parameter from the electrical parameters. Likewise, the resistance of a coil of a magnetic valve is dependent on the temperature of the coil. This means that through compilation of the current and voltage parameters the resistance can be derived. Based on the resistance the temperature is then calculated. Particularly advantageous in this context is that even one of the parameters, such as the current or the voltage, or a calculated parameter, such as the resistance can be used as the temperature-parameter. In the following paragraphs, this temperature-parameter will be referred to simply as temperature. In the event of a defect, the leakage does not escalate spasmodically but rises continuously, and therefore with the use of the temperature measurement detective injectors can be detected and replaced before a total break-down of the IC-engine. The process can be particularly advantageously applied for a magnetic valve. In this case the temperature of a magnet(ic) coil of a magnetic valve is measured and based on such a measurement the existence of a leakage is ascertained. It is especially advantageous, that the measurement of the leakage is possible without measuring the individual return flow quantum of the injectors. As a result the measuring effort is evidently reduced. In systems where the individual return flow quantums cannot be measured or are difficult to be measured, a diagnosis is possible only with this methodology. In this context the existence of a leakage is always then ascertained, if the temperature parameter exceeds a pre-determinable threshold value and/or if the time-gradient of the temperature parameter exceeds a pre-determinable additional threshold value and/or if the time-dependent alteration of the time-gradient of the temperature parameter exceeds a pre-determinable yet another threshold value. In order to improve the identification of the leakage, the temperature of the IC-engine is taken into consideration when defining threshold values to be stipulated, since the temperature can have an adulterating effect on the coil temperature. Preferably even the temperature of a single cylinder is measured in this context, since within the IC-engine gradients/differences in temperature may occur. The temperature can in principle be measured in many different ways, for instance using temperature sensors or similar devices. This is in particular meaningful with Piezo-actuators. Under an advantageous design form the temperature parameter is determined from the coil-current and in this particular case preferably from the pulse duty-factor of a holding-current control. Preferably the temperature parameter is determined from the extent of the current level under a fixed pre-determined pulse duty-factor. Through this, the existing control units can be used; additional sensor elements would be superfluous. It is particularly advantageous, if in phases, in which no activation of the actuator happens, this is charged with a test-current. Hereby preferably a constant current is chosen and the temperature parameter is determined from the level or extent of the voltage that gets set. This means that the temperature parameter is determined from the ratio of voltage and current, where respectively one of these parameters set in a ratio is constant at the actuator whereas the other parameter is measured. The invention-based methodology can be performed both when the vehicle is in motion through customary control unit, which controls the IC-engine in the running state, as well as during maintenance work through a diagnosis tester, which in the following paragraphs will also be referred to as tester. Here, a measuring is also possible on older cars without any alteration to the control instrument. In so doing, distribution of the individual elements and tasks to the control unit and to the tester according to choice is possible. This only denotes that the means for the execution of the invention-based methodology are at least partially an integral part of the control unit, and/or the means to execute the invention-based methodology are at least partially an integral part of the tester. It is particularly advantageous, if the difference between two temperature parameters measured at different rail pressures, is evaluated. Drawing Further advantages and characteristics of the invention are objects of the following description and the illustration by drawing of a design example of the invention. The figures/drawings illustrate: Figure 1 a schematic sectional view of an invention-based device with a magnetic valve injector Figure 2 schematically the pulse duty factor on the coil temperature and Figure 3 a flow-chart of a design variant of the methodology. Description of design examples The starting of the injection and the quantity of injection are set by an electrically-actuated injector incorporated in a cylinder 300 of an IC-engine, for example, a magnetic valve injector illustrated in Figure 1. The fuel is carried by a high-pressure fuel-source 95, which encompasses, for example in a Common-Rail-System, at least a high-pressure fuel-pump and an accumulator (Rail), through a high-pressure connection 90 into a high-pressure fuel-intake (inflow) channel 92 to an injector nozzle 60, also known as jet needle, as well as through fuel-intake choke/throttle 100 into a valve control chamber 50. The valve control chamber 50 is connected to a fuel-return-line 10, through a discharge choke/throttle 80, which can be opened through a magnetic valve, consisting of a magnetic coil 20, a magnetic armature 30 and a valve ball 40. In closed position of the discharge choke 80 the hydraulic force on a valve piston 110 out-weighs the force on a pressure shoulder 62 of the jet needle 60. Consequently the jet needle 60 is pressed into its seating and seals the high-pressure channel 92 tightly to the engine compartment (not illustrated). If the engine is not running and there is no pressure for example in the high-pressure accumulator, a jet spring 64 closes the injector. With the activation of the magnetic valve, i.e. the magnetic coil 20 and therewith the magnetic armature 30 and the valve ball 40, the discharge choke 80 is opened as the valve ball is displaced from its seating. The fuel-intake choke 100 prevents a complete pressure equalization, so that the pressure in the valve control chamber 50 and thus the hydraulic force on the valve piston 110 falls. As soon as the hydraulic force goes below the force acting on the pressure shoulder 62 of the jet needle 60, the jet needle 60 opens. The fuel now flows through injection holes 70 into a combustion chamber 310 of an engine. Under a not-anymore actuated magnetic valve (magnetic coil 20), the magnetic armature 30 is pressed downwards through the force of the valve spring 22. The valve ball 40, closes the discharge choke 80. Thereby, pressure builds-up again in the valve control chamber 50, through the inflow of the fuel-intake choke 100, which corresponds to the rail pressure. This higher pressure exercises a higher force on the valve piston 110, so that the jet needle 60 closes again. The through-flow of the fuel-intake choke 100 determines the closing speed of the jet needle 60. This indirect actuation of the jet needle 60 through a hydraulic power pack system or power-amplifier system is used, because the forces needed for a rapid opening of the jet needle 60 cannot be attained with the magnetic valve. Thereby in addition to the injected fuel the control quantity in excess of the injected fuel quantity reaches the fuel-return-line 10 through choking of the control chamber. In case of a leakage the injector body, including its built-in components, gets heated up. The leakage quantity is itself hot and heats up the magnetic armature 30 and the magnetic coil 20 located on the fuel-return-line. Basic idea of the invention is now, to ascertain the existence of a leak, proceeding from the temperature of at least one part of the injector, especially the temperature of the magnetic coil 20. The temperature of the magnetic coil 20 for instance is determined through the already well-known pulse duty factor holding current in a control unit 200. Thereby connecting lines 205, 210, which in any case are necessary to activate the magnetic coil 20, are used to determine the temperature, so that additional lines can be dispensed with, which is of particular advantage. The coil temperature is determined for example from the extent or magnitude of the current level or niveau at a fixed pre-determined duty factor. As illustrated in Figure 2, the pulse duty factor of the holding current alters itself proportionally to the coil temperature. From the pulse duty factor of the holding current the temperature of the magnetic coil 20 can therefore be derived. If the temperature of the magnetic coil 20 exceeds a pre-determined threshold value and/or a predetermined time-gradient of the temperature exceeds and/or a pre-determined parameter of the time-dependent alteration of the time-gradient of the temperature exceeds the corresponding threshold values stipulated, then the existence of a leakage is ascertained. In order to exclude errors in the leakage measurement, the temperature of the engine and in particular the temperature of the individual cylinders 300, in which the fuel injector valve is built-in, must be taken into consideration when defining the thresholds. The above described methodology is ideally suitable for IC-engines in running operation. This means that the process is performed while the IC-engine is running. It is particularly advantageous if the invention-based process is carried out and/or initialized through an external diagnosis tester. This is then done in the context of maintenance work in the workshop/garage. If the use of such a diagnosis tester, referred to as tester in the following paragraphs, the application of the methodology described below is particularly advantageous. This methodology can also be carried out by the control unit when the vehicle is in motion. The measurement of the temperature here is preferably done in a phase where there are no injections. The measuring can thereby take place between two injections or in a phase where no fuel is dosed. For the measurement, the actuator is charged with a constant current. From the current-voltage ratios, which are either known or are measured, the resistance of the actuator is obtained and thus the temperature of the actuator. At an easily accessible point the cable loom on a plug-socket assembly is disconnected and the tester is coupled with the use of an adapter between engine-controller and injector. Thereby the tester gets a measuring tap of the injector-connections. In order to measure the temperature or to measure the resistance, the available pause between injection-controls of the engine controller on the injector is determined through a corresponding triggering. In these pauses a constant current is embossed on the injectors. A fall in voltage sets in, which is recorded. Based on the embossed current and the measured voltage, the resistance and thus the temperature is calculated. The measurement exercise is automatically carried out for each injector at a low and at a high Rail-pressure. Through the evaluation of the differential AT of the temperature at different Rail-pressures, the influence of different basic thermic conditions can be eliminated, which are attributable to the respective cylinder position. If the differential AT of a cylinder exceeds a specified threshold or limit value, then this injector is identified as defective. Figure 3 illustrates the plan for testing with the use of a flow-chart. The test-program starts with step 400. In step 410 a pressure regulator is actuated in such a way that an initial Rail-pressure level gets set. In step 420 a time-period is awaited in which the temperature of the injector stabilizes at the set Rail-pressure level. In step 430 the coil temperature of all cylinders is determined through charging them with a constant current and compiling the fall in voltage. In step 440 the pressure regulator is actuated in such a way that, the second Rail-pressure level gets set. Ideally the second Rail-pressure level is significantly higher than the first Rail-pressure level. In step 450 a time-period is awaited in which the temperature of the injector stabilizes at the set level of rail-pressure. In step 460 the coil temperature of all cylinders is determined through charging them with a constant current and compiling the fall in voltage. Subsequently, in step 470 the differentials AT of the two temperature parameters are determined at different Rail pressures and are compared with a threshold value. If the determined differential of at least one cylinder is bigger than a threshold value, then a defect is recognized. In step 480 the result is displayed. The testing plan ends with step 490. Claims of the Patent Process for leakage testing of a fuel-injection valve of an IC-engine, is thereby characterized, that a temperature parameter, which characterizes the temperature of at least one part/component of the fuel-injection valve, is determined and proceeding from this, the existence of a leakage is ascertained. Process according to Claim 1, is thereby characterized, that the temperature parameter is determined from the pulse duty factor of a holding current. Process according to Claim 2, is thereby characterized, that the temperature parameter is determined from the extent or magnitude of the current level at a fixed pre-determined pulse duty factor. Process according to Claim 1, is thereby characterized, that the temperature parameter is determined from the ratio between voltage and current, where respectively one of these parameters set in a ratio is constant at the actuator, whereas the other parameter is measured. Process according to Claim 4, is thereby characterized, that the temperature parameter is determined in phases, in which the actuator is not activated. Process according to Claim 1, is thereby characterized, that the differential of two temperature parameters is evaluated at different fuel-pressures. Process according to Claiml, is thereby characterized, that a leakage is ascertained, if the temperature parameter exceeds a pre-determined threshold value and/or if the time-gradient of the temperature parameter exceeds an additional pre-determined threshold value and/or if the time-dependent alteration of the time-gradient of the temperature exceeds yet another pre-determined threshold value. 8. Process according to Claim 6, is thereby characterized, that the temperature of the IC-engine is taken into account when defining the thresholds. 9. Process according to Claim 9, is thereby characterized, that the temperature of a cylinder (300) of the IC-engine, in which the fuel-injection valve is built-in, is taken into consideration when defining the thresholds. 10. Device/instrument for leakage-testing of a fuel-injection valve of an IC-engine, is thereby characterized, that means are provided, which determine a temperature parameter which characterizes the temperature of at least one component of the fuel-injection valve and based on this ascertains the existence of a leak. 11. Device/instrument according to Claim 10, is thereby characterized, that a magnetic-valve is used as an actuator. 12. Device/instrument according to Claim 10, is thereby characterized, that such means are at least partially constituents of a control unit, which controls the IC- engine when the vehicle is in motion. 13. Device/instrument according to Claim 10, is thereby characterized, that such means are at least partially components of a diagnosis tester. Summary In a process and a device/instrument for leakage testing of a fuel-injector valve of an IC-engine, a temperature parameter is determined, which characterizes the temperature of at least one part/component of the fuel-injection valve. Based on this temperature parameter, the existence of a leakage is determined.

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2157-CHENP-2007 EXAMINATION REPORT REPLY RECEIVED 20-01-2015.pdf

2157-CHENP-2007 AMENDED CLAIMS 31-12-2013.pdf

2157-CHENP-2007 ASSIGNMENT 20-01-2015.pdf

2157-CHENP-2007 CORRESPONDENCE OTHERS 01-10-2013.pdf

2157-CHENP-2007 DECLARATION 31-12-2013.pdf

2157-CHENP-2007 FORM-3 31-12-2013.pdf

2157-CHENP-2007 OTHER PATENT DOCUMENT 31-12-2013.pdf

2157-CHENP-2007 POWER OF ATTORNEY 31-12-2013.pdf

2157-CHENP-2007 CORRESPONDENCE OTHERS 11-11-2014.pdf

2157-CHENP-2007 EXAMINATION REPORT REPLY RECEIVED 31-12-2013.pdf

2157-CHENP-2007 POWER OF ATTORNEY 20-01-2015.pdf

2157-chenp-2007-claims.pdf

2157-chenp-2007-correspondnece-others.pdf

2157-chenp-2007-description(complete).pdf

2157-chenp-2007-drawings.pdf

2157-chenp-2007-form 1.pdf

2157-chenp-2007-form 3.pdf

2157-chenp-2007-form 5.pdf

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2157CHENP2007-Petition for POR.pdf