WO2019110169A1

WO2019110169A1 - Method and device for characterizing the injection behavior of an injection valve for liquids

Info

Publication number: WO2019110169A1
Application number: PCT/EP2018/078014
Authority: WO
Inventors: Clemens Majer; Wolfgang Sander; Stefan Muelders; Markus Boerner; Iris Hartung
Original assignee: Robert Bosch Gmbh
Priority date: 2017-12-08
Filing date: 2018-10-15
Publication date: 2019-06-13
Also published as: EP3721071B1; CN111465763B; JP2021505812A; DE102017222234A1; CN111465763A; EP3721071A1

Abstract

The invention relates to a method and to a device for characterizing the injection behavior of an injection valve (15) for liquids, which method comprises the method steps of injecting liquid into a measurement chamber (11) by means of the injection valve (15), radiating light into the measurement chamber (11) onto liquid discharged from the injection valve (15) as a spray pattern (18), detecting and scanning temporally successive spray images which are produced by light reflected at the spray pattern (18) discharged from the injection valve (15) and are imaged at a capturing apparatus (12) in order to obtain spatially resolved intensity distributions, evaluating the intensity distributions associated with the detected and scanned spray images, wherein those image matrix elements that contain image information associated with the imaged spray pattern (18) are identified in the intensity distributions, and a measure of the injection behavior is determined on the basis of the identified image matrix elements and the time development thereof.

Description

Method and device for characterizing the injection behavior of a

Injector for liquids

description

The invention relates to a method for characterizing the injection behavior of an injection valve for liquids and to an apparatus for carrying out such a method.

State of the art

For functional testing or characterization of injection valves, in particular of common rail injectors, an accurate measurement of characteristic variables, such as, for example, is generally required. the injection rate for single or multiple injections neces sary to be able to recognize, for example, start of injection and injection end of an injection process. For this purpose z.T. different measurement techniques is set, under which the detection of primary parameters such as the injection rate based on the measurement of pressure and sound velocity in a measuring chamber is used relatively frequently. In this prior art, however, a relatively complex pressure sensor signal conditioning by means of a low-pass filtering is necessary to compensate for interference signal due to natural oscillations of the measuring chamber.

DE 10 2011 007 611 A1 discloses an apparatus and a method for determining at least the spray quantity and / or the spray rate of a liquid sprayed with a valve. The device has a measuring chamber and an interface for receiving the valve, at least one sensor for measuring a prevailing in the measuring chamber state, and an interconnected with the sensor evaluation for determining the spray rate and / or the spray rate at least in dependence on the measured to stand on , The device and the method for determining the spray quantity and / or the spray rate make it possible to simultaneously determine and evaluate a further parameter of the liquid. This further parameter is the spray pattern of the sprayed liquid and is recorded by a device for beam imaging of the sprayed liquid. For this purpose, an opti- used see chamber, wherein the jet pattern is determined and evaluated simultaneously to the spray rate and / or the injection rate of the evaluation.

epiphany

Advantages of the invention

The method with the features of claim 1 has the advantage that it is relatively easy and inexpensive to implement and also provides quantitative Re results. To this end, the method comprises the steps of injecting liquid through the injection valve into a measuring chamber, injecting light into the measuring chamber onto liquid ejected from the injection valve as a spray pattern, detecting and scanning temporally successive jet images coming from at interfaces of the Injection valve ejected spray patterns reflected and to a recording device gebil detem light are generated to th spatially resolved intensity distributions, the evaluation of the detected and scanned beam images depending Weil associated intensity distributions, wherein in the respective intensity distributions such image matrix elements are identified, which the contained image information associated with the spray pattern, and a measure of the injection behavior is determined on the basis of the respectively identified image matrix elements or pixels and their time evolution. The invention is therefore based on the finding that, with a suitable measuring chamber pressure at a phase boundary between a gas phase representing an injection process

se / liquid phase and located in the measuring chamber Flüssigpha se / gas phase and then imaged as an optical snapshot light represents a temporally "frozen" state of the injection behavior, since the injection process in the filled with the liquid medium measuring chamber egg ne manifesting itself as a spray pattern cavitation occurs so that opening and closing of the injector is clearly correlated with the occurrence and disappearance of cavitation; the evaluation of such "frozen" snapshots of a cavitation event thus provides information about its temporal development, from which a parameter for characterizing the injection behavior can be derived. Thus, it is possible to unambiguously determine the beginning and end of an injection process due to the then occurring abrupt changes in the intensity distributions of the beam images. The invention Method is largely insensitive to natural oscillations of the measuring chamber due to the underlying optical measurement technique.

Further advantageous developments and refinements of the invention will become apparent from the measures listed in the dependent claims.

An expedient embodiment of the invention is that as a measure of the injection behavior serving as a parameter relative injection rate on hand of the following relationship

where n (t) is the relative injection rate in function of time t, with G a threshold between high and significantly lower intensity values, with l (P _j , t) the intensity of a j th image element matrix j is a summation index extending from 1 to m, where m represents the total number of evaluated image matrix elements and K _j denotes a respective correlation factor, wel cher one in each associated one image matrix element detected light intensity information value l (P _j, t) taken into account, with only such image matrix elements P _j are taken into account in the summation, the light intensity values are greater than the threshold value G or equal to the threshold value G, to identifi associated with the spray pattern contained in the respective beam image-forming matrix elements adorn.

Conveniently, the receiving device is adjusted so that a cross-sectional plane of the ejected spray pattern forms sharply abge as a spray pattern, whereby a two-dimensional image of the spray pattern is displayed.

A variant of the method, with which a quasi-three-dimensional image of a spray pattern on which the optical detection is based, may be that different cross-sectional planes are imaged and scanned in temporally successively detected beam images, in each case the focal length of the recording device is changed and / or the recording device is moved with respect to their optical distance to the measuring chamber.

A development of the invention, with which a further characteristic for characterizing the characterization of the injection behavior is optically recoverable, can best hen that as a measure of the injection behavior a Strahlausbreitungsgeschwin speed in a cross-sectional plane of the spray pattern (spray pattern) based on the following relationship

where v (ti _{+ i} ) is the beam propagation velocity at time t _{+ i} , where i is an index for a respective beam image to be processed, where n is a beam spread radius at time t, for an i-th beam image, and n _{+ i} a Strahlausbrei tion radius at time t, _{+ i are designated} for an (i + l) -th jet image, wherein at least two temporally successive beam images are detected and evaluated by identified in the i-th beam image image elements who the with which outward pointing ends of the beam lobes of a projected spray pattern and are arranged approximately on an imaginary circular ring with a Strahlausbreitungsradius n, and in the (i + l) -th jet image image elements are identified, which with the outward-pointing ends of beam lobes of the then mapped spray pattern kor respondieren and approximately on an imaginary circular ring with a beam spread radius n _{+ i} are arranged.

In this case, a calibration of the Strahlausbreitungsradien by a relevant Abbil relevant object size, preferably a nozzle diameter of the injection valve to be tested, and / or a magnification of the recording and / or a resolution of the recording device is taken into account is / are, so that the parameter in absolute units representable is.

In accordance with an advantageous embodiment of the invention, hydraulic measurements for determining a hydraulically obtained parameter such as the injection rate and / or the injection quantity in the measuring chamber are carried out simultaneously with the optical detection of beam images, with optically obtained measuring data with hydraulically obtained measurement data with respect to the parameter be corrected. As a result, the hydraulically obtained measurement results can be checked and verified directly by means of the optical detection performed at the same time, so that measurement artefacts can be detected in the hydraulic measured value detection because of the measurement artifacts that are required for the required low-pass filtering.

Furthermore, from the optically determined relative injection rate n (t), an injection rate normalized to a maximum of 1 (t) and by inclusion of the hydraulic measurement results, an absolute injection rate A (t) can be determined by scaling via the hydraulically measured injection rate, which corresponds to the integral over the rate takes place.

In the combined use of optical and hydraulic Meßwerterfas solution can be determined as a further parameter, a beam pulse for characterizing the injection behavior, wherein the jet pulse from the optically ge acquired beam propagation velocity v (t,) and from a hydraulically ge obtained injection quantity is determined by respective product formation.

Conveniently, a three-dimensional image of the spray pattern can be generated from the various cross-sectional planes at each point in time of the injection. Furthermore, a beam propagation velocity along the beam axis is determined from the three-dimensional image of the spray pattern.

The device intended for carrying out the method according to the invention is simply designed and reliably delivers quantitative results for characterizing the injection behavior of an injection valve or fuel! njektors. For this purpose, it is provided that the device comprises an evaluation device, which has a data transmission connection to the recording device to ver work and evaluate scanned by the receiving device and ver to evaluate the evaluation in detected by the recording intensity distributions of respective beam images such image matrix elements, which an associated spray pattern associated image information included, and based on the respective identified image matrix elements and their time evolution determines a measure of the injection behavior. According to one embodiment of the invention, the receiving device along its optical axis by means of an associated positioning displacer bar to change the optical path length between the receiving device and the measuring chamber. This makes it possible to successively ver different cross-sectional planes ejected from the injector

Visually traversing and detecting spray patterns in order to achieve a quasi three-dimensional representation. Conveniently, the Aufnahmeein device is designed as a digital camera to detect a spatially resolved intensity curve for each detected and scanned beam image, which simplifies the evaluation of optically acquired data and allows a compact design of the device.

Brief description of the drawings

Embodiments of the invention are explained in more detail in the following description and in the accompanying drawings. The latter show in schematic views:

1A is a sectional view of a device according to the invention, comprising a measuring chamber with an injector received therein, a arranged on an optical access of the measuring chamber illumination device and an au outside the measuring chamber arranged receiving device,

Fig. 1B is a diagram for a first and then taking place a second injection respectively during the injection period detected hydraulic measurements based on two diagrams and temporally coincident thereto optically detected cavitation images together with a pulse train for the injection of the current to tes injector and a control signal represents the control of the Beleuchtungsein direction, wherein the time axis runs along the abscissa and in the diagrams, the hydraulically detected injection mass and their temporal Ablei direction are plotted as a function of time,

2A is a flowchart showing the essential method steps of a first embodiment of the control method according to the invention, 2B shows a flowchart with the essential method steps of a two-th embodiment of the control method according to the invention,

2C is a flowchart with the essential method steps of a third embodiment of the inventive control method,

3A shows a flow chart with the essential method steps of a first embodiment of the evaluation method according to the invention in order to determine a measure of a relative injection rate of an injector to be tested,

FIG. 3B shows a spray pattern of an injector optically detected as a cavitation image, which serves as the basis for the first embodiment of the evaluation method, FIG.

4A shows a flowchart with the essential method steps of a two-th embodiment of the evaluation method according to the invention in order to determine a measure of the beam propagation in an image plane of a spray pattern ejected from a test object to be tested,

4B shows a projection of two temporally immediately successively detected cavitation images as a basis for the second embodiment of the evaluation method,

4C shows a flow chart with the essential method steps of a third embodiment of the evaluation method according to the invention in order to determine a measure of the beam propagation along the beam axis of a spray pattern ejected from an injector to be tested,

4D is a diagram for a rough illustration of the principal temporal divergence behavior of a spray pattern ejected from the injector, which is illustrated in a simplified and sketch-like manner on the basis of its outer radius respectively assigned to different times, as the basis for calculating the beam propagation velocity to be determined;

4E is a diagram for illustrating the principle temporal Diver genzverhaltens ejected from the injector spray pattern as calculation basis for the beam propagation speed to be determined in a single image plane,

FIG. 5A shows an evaluation mask, which has been illustrated on the basis of a cavitation image, for evaluation in order to suppress unwanted reflections on the measuring chamber wall in the evaluation, FIG.

5B shows an evaluation mask, which is illustrated by means of a cavitation image and is used in the evaluation in order to suppress reflections outside the beam,

FIG. 5C is an evaluation mask illustrated by means of a cavitation image, which is used for the evaluation in order to selectively analyze individual beam lobes in the cavitating image, as well as FIG

6 shows a measured measurement diagram acquired and evaluated in accordance with the method according to the invention, in which a normalized injection rate F (t) is plotted along the ordinate, while the time axis runs along the abscissa, wherein groups of optically acquired measurement data are represented by the fraction hel Image matrix elements of individual sensor images of a temporal sequence in functional dependence on the recording time of the recording device during an injection process are shown, and in comparison thereto a simultaneously hydraulically detected measurement curve is shown.

Description of the embodiments

Fig. 1A illustrates in a highly schematically held sectional view of the device generally designated 10, which has a measuring chamber 11 and egg ne optical pickup device 12 and a lighting device 13. The measuring chamber 11 is used for testing injectors and has a housing 14 which is provided for receiving an injector 15 to be tested, which is centrally inserted into a designated opening in a th above wall of the housing 14, so that with spray holes ver seen injector end protrudes into the measuring chamber 11. In the housing 14, a pressure sensor 16 and a Ultraschallwandlereinrich device 17 are received, which is formed of an ultrasonic source and an ultrasonic sensor. As a result, the measuring chamber 11 has a functionality as a hydraulic pressure increase analyzer; When the injector 15 injects liquid into the liquid-filled measuring chamber 11 through its injection openings or injection holes, thereby increasing the pressure in the measuring chamber 11, it is possible in a conventional manner to measure the pressure and the speed of sound in the measuring chamber 11 simultaneously by means of the pressure sensor 16 and the ultrasonic transducer means 17 a characteristic characteristic of the injector, namely the injection rate can be determined.

By the illumination device 13 and the optical recording device 12 with the measuring chamber 11 cooperate, the device 10 opti cal sensor functionality to the generated during the injection process to the Spritzlö Chern the injector 15 as a cross-sectional plane of the spray pattern 18 by the fuel emerging there spray jet 30 optically to detect and quantitatively analyze by means of an evaluation, not shown. Since to the case 14 on its the injector 15 opposite angeord Neten bottom side 14 ^'has an approximately centrally located therein optical access 20, which is formed as an optically transparent window. The lighting device 13 is formed as an annular light emitting diode array (LED array) and on the outside so on the bottom side 14 ^'of the housing 14 is arranged, that the ring inner surface of the LED array 13 from the bottom side 14 ^' projecting portion of the optical window 20th encloses. Light emitted by the annular LED arrangement 13 then passes into the measuring chamber 11 via the optical window 20. In order to largely suppress unwanted reflections of the light radiated into the measuring chamber on the inner wall of the measuring chamber 11, the inner wall of the measuring chamber 11 is formed blackened that in the measuring chamber 11 irradiated light is reflected substantially at phase boundaries, which arise by cavitation currency end of the injection process from the spray holes of the injector 15 to be tested in the form of beam lobes and form a spray pattern 18. At least a portion of the reflected or reflected light occurs through the opti cal window 20 and through the inner ring of the LED assembly 13 through outward and is then deflected by a deflection mirror 21 by 90 ° to a receiving device 12 as a spray pattern or Cavitation image 30 detected too with an upstream objective 22 imaging the falling light beam from the deflection mirror 21 onto an image sensor (not shown) of the recording device 12, which in the exemplary embodiment is a high-speed digital camera with a CMOS or CCD (charge coupled Device ") - array is formed as an image sensor. Expediently, the annular LED arrangement 13, the optical window 20 and the injector 15 are arranged concentrically with one another along the longitudinal axis 11 ^'of the measuring chamber 11. The receiving device 12 is mounted together with the upstream lens 22 on a positioning slide 24 which is formed horizontally displaceable along a guide 25 to vary the image plane of the receiving device 12 un depending on the focus setting can. A control and evaluation (not shown) serves on the one hand for driving the posi tionierschlittens 24, for controlling the injection behavior of the injector 15, for pulsed control of the light emission of the LED array and time on it tuned recording behavior of the receiving device 12 and on the other hand for evaluation the light intensities detected by the image sensor of the recording device 12; For this purpose, the control and evaluation via control and data lines (not shown) with an electronic control unit of the injector, electrically connected to the LED array, with the recording camera and its lens and control electronics of the positioning slide. In addition, the control and evaluation device performs a correlation of the optically obtained data with the same time from the pressure and Schallgeschwindigkeitsmes solution hydraulically obtained data.

Fig. 1B shows a graph 27, in which with the invention Vorrich device 10 scored measurements are shown, on the one hand hydraulically recorded measurements in two diagrams 28, 28 ^' for two consecutive injections of the injector to be tested and each temporally correlated and optically detected Cavitation images 30 ^' , 30 ^'' include. In the two diagrams 28, 28 ^' , the injection mass m determined on the basis of the pressure p measured in the measuring chamber and the measured speed of sound c and the injection rate dm / dt as a function of the time t during a multiple injection are composed of for example illustrated, Main and Nachein injection represented. Each of the two diagrams 28, 28 ^' is a Steuerimp ulsfolge assigned, with which the injection of the injector is controllable, in which for the pilot injection, for example, a triangular sawtooth pulse 29, for the main injection, a trapezoidal pulse 29 ^' and for Nachein injection a trapezoidal pulse 29 ^{"is used} by opposite the main injection shorter pulse duration. Further, to each of the two diagrams 28, 28 ^', a control signal 39 for driving the LEDs of the lighting device processing is shown, with which a synchronous injection for illumination of the measuring chamber is effected, wherein the control signal has a We sentlichen rectangular pulse shape whose pulse length so bemes sen is that this extends over the pre-, main and post injection. As further illustrated in FIG. 1B, the higher the injection rate dm / dt, the more pronounced a cavitation event, since the cavitation image 30 ^' recorded simultaneously with a pre-injection is significantly weaker than the cavitation image 30 ^" recorded during a main injection at a high injection rate. whose beam lobes extending in the radial direction, in contrast, have a significantly longer range.

FIG. 2A shows, on the basis of a highly schematically kept flow chart 100, the essential method steps of the inventive control method according to a first variant of the method, which serves for various device components, ie the camera, its objective and the LED arrangement with the injection process of the injector to be tested Synchronisie ren. In a first method step 101, a control pulse synchronously to the electronics of the injector 15, the LED array 13, the recording camera 12, the lens 22 is transmitted so that the injector 15 ejects fuel from its Sprühlö chern and into the measuring chamber 11th injected; at the same time, the LED ring 13 emits a light pulse, the lens 22 adjusts aperture and focus, and opens the shutter 12 for a predetermined exposure time to light that emits from the LED ring 13 at the phase boundary of the injector Spray pattern 18 is ejected fuel is reflected from the measuring chamber 11 via the optical window 20, the deflection mirror 21 and the lens 22 on the image sensor of the recording camera 12 passes or forms abge. In a second method step 102, which takes place during the exposure phase, the image plane of the objective 11 is focused on the plane of the injection holes of the injector 15 in order to image the spray pattern or cavitation image typically generated during the injection process of the injector sharply onto the image sensor. After these two adjustment steps 101 and 102, in order to start a sequence of temporally successive individual images. th, in a subsequent process step 103 again a Steuerimp uls to the electronics of the injector 15, the LED array 13 and on the camera on camera 12 delivered, whereupon in a subsequent step 104, a first frame is detected. In a next method step 105, the immediately before currently detected individual image as image matrix with Bildmatrixele elements or pixels, in which the respective light intensities are detected, stored on egg nem storage medium. In a subsequent test step 106 is continuously queried whether the preset sequence of frames has already been processed, with a negative query result, a return to step 103 and the procedure steps 104 and 105 for detecting and storing a respective next frame within a step 103 to 106, while incrementing a loop index by one counter 1, while on the other hand with a positive interrogation result, that is, when a sequence of frames is detected and stored, the loop is terminated to leave it at a subsequent step 107 to initiate a jump into an evaluation procedure. The individual images obtained in this embodiment of the control and measurement data acquisition method are, as a result of the optical device configuration, cross sections through the cavitation generated by the injector along the image plane which is set constant on the objective 22.

FIG. 2B shows, on the basis of a highly schematically held flow chart 100 ^', the essential method steps of the inventive control method according to a second variant of the method, which serves for different component components, ie the camera, its lens and the LED arrangement and the positioning slide with the injection process of the to test synchronizing the injector. In contrast to the first embodiment of the control and measurement data acquisition method 100, in the second embodiment of the control method 100 ^' , the positioning carriage 24 is additionally actuated to move the camera 12 mounted thereon along with the objective lens 22 along the guide rail 25, together with the objective lens 22 can. In an initializing method step 101 ^' , the positioning carriage is moved to a starting or starting position. Then, in a next method step 102 ^', a control pulse signal is output synchronously to the electronics of the injector 15 to be tested, the LED arrangement 13, the recording camera 12, and its objective 22, such that the injector 15 ejects fuel from its injection ports and injects it into the metering chamber 11; Simultaneously, the LED ring 13 emits a Lichtim pulse, the lens 22 aperture and focus and opens the Aufnahmekame ra 12 for a predetermined exposure time their closure, so that light emitted from the LED ring 13, at the phase boundary of the Injector as a spray pattern 18 released fuel reflected and from the measuring chamber 11 via the optical components 20, 21, and 22 on the image sensor of the Aufnah mekamera 12 passes or is mapped. In a still taking place during the Belich processing phase step 103 ^' , the image plane of the lens 22 is focused on the plane of the injection holes of the injector 15 to map the spray pattern typically generated during the injection process of the injector as Kavita tion image sharp on the image sensor. After these adjustment steps 101 ^' , 102 ^' and 103 ^' , in order to start a sequence of temporally successive individual images, in a subsequent method step 104 ^', a control pulse signal is sent to the electronics of the injector 15, to the LED arrangement 13, to the recording camera 12 and delivered to the lens, whereupon in a immediately following method step 105 ^' captures a single image and in a further method step 106 ^{' is} stored as an image matrix in a storage medium abge. After storing 106 ^' , a control pulse signal is output to the positioning device or the positioning carriage in a subsequent method step 107 ^{' in} order to set the positioning carriage set to a start position x at step 101 ^' by a feed Dc to a new position x: = xo + Dc to proceed; this changes the image plane by Dc. In a subsequent test step 108 ^' it is continuously queried whether the preset sequence has already been processed, with a negative query function being a return to step 104 ^' and the procedure with the steps 105 ^' and 106 ^' for detecting and storing a respective cyclically through the next frame within a step 104 ^' to 108 ^' , the loop index being incremented by one count of 1 for counting the frames, while on the other hand, if the sequence of frames is detected and if the result is positive is ab stores, the loop is terminated or left to initiate in a subsequent procedural step sequential step ^' a jump in a - still to erläu terndes - evaluation. Since the position of the positioning carriage changes by one Dc each time the loop 104 ^' to 108 ^' passes through, the control and measurement data acquisition methods used in this embodiment are different. In contrast to the first control method variant according to flow chart 100, the spray pattern of the injector virtually three-dimensionally by means of a single sequence in a three-dimensional Time is displayed.

2C shows, with reference to a highly schematically held flow chart 100 ^", the essential method steps of the inventive control method according to a third variant of the method, which serves various device components, ie the camera, its lens and the LED arrangement and the positioning carriage with the injection process of FIG to test synchronizing the injector. In contrast to the first embodiment of the control and measurement data acquisition method 100, in the third embodiment of the control method 100 ^", additionally the positioning carriage 24 is driven to move the receiving camera 12 mounted thereon along with the objective lens 22 independently of the set objective focal length along the guide rail 25 to be able to. In an initializing method step 101 ^" , the positioning carriage is moved to a start or start position. Subsequently, in a next method step 102 ^", a control pulse signal is output synchronously to the electronics of the injector 15 to be tested, the LED arrangement 13, the recording camera 12, and its objective 22, so that the injector 15 ejects fuel from its spray holes and into the measuring chamber 11 injected; Simultaneously, the LED ring 13 emits a Lichtim pulse, the lens 22 aperture and focus and opens the Aufnahmekame ra 12 for a predetermined exposure time their closure, so that light emitted from the LED ring 13, at the phase boundary of the Injector as a spray pattern of released fuel reflected and passes from the measuring chamber 11 via the optical components 20, 21, and 22 on the image sensor of the Aufnah mekamera 12 or imaged. In a still taking place during the Belich processing phase step 103 ^" , the image plane of the lens 22 is focused on the plane of the injection holes of the injector 15 to map the spray pattern typically generated during the injection process of the injector as Kavita tion image sharp on the image sensor. After these adjustment steps 101 ^" , 102 ^" and 103 ^" , in order to start a sequence of temporally successive individual images, in a subsequent method step 104 ^" a control pulse signal to the electronics of the injector 15, to the LED array 13, the recording camera 12 and the lens delivered, whereupon in an immediately following step 105 ^" captures a single frame and abge in a further step 106 ^" as an image matrix in a storage medium stores. In a subsequent test step 107 ^" , a query is continuously made as to whether the preset temporal sequence of individual images of an image element has already been processed, with a negative query result returning to step 104 ^" and the procedure comprising steps 105 ^" and 106 ^" for detecting and storing a respective next frame within a step 104 ^" to 107 ^" loop by incrementing a loop index by one counter 1 cyclically, while demge with a positive polling result, ie when a temporal sequence of frames of an image plane is detected and stored, the Loop is exited or left to deliver in a subsequent process step 108 ^" a control pulse signal to the positioning or the positioning slide to the set at step 101 ^" to a start position xo posi tion carriage by a feed Dc to a new Pos x: = xo + Dc to drive; this changes the image plane by Dc. In a subsequent step, the test step 109 ^" is continuously inquired whether the preset sequence of image planes has already been processed, with a negative query result, a return to step 104 ^" and the procedure with the steps 105 ^" and 106 ^" for detecting and storing one The next frame of the next image plane and its temporal sequence are cycled within a 104 ^" to 109 ^" loop, with the loop in dex incremented by one count of 1 for counting the frames, while the result is a positive interrogation That is, when the sequence of frames of all image planes is detected and stored, the loop is terminated or exited, in a subsequent procedural step 110 ^" to initiate a jump into an evaluation method to be explained below. Since the position of the positioning carriage changes by one Dc with each pass of the loop 104 ^" to 109 ^", the individual images obtained in this embodiment of the control and measurement data acquisition method are cross-sections staggered with respect to one another, the injector located in the respective measuring chamber generated spray pattern successively scanned, so that - in contrast to the first Ste- tion method variant according to flowchart 100 - by means of a single Se quenz the spray pattern of the injector is practically three-dimensionally displayed.

3A shows a flow chart with the essential method steps of the evaluation method 200 according to the invention in accordance with a first embodiment, wherein a respective injection rate of the injector is determined on the basis of spray patterns optically detected as cavitation images. By way of example, FIG. 3B shows such a sensor image or cavitation image 30, which is digitally detected by the image sensor of the recording device and has beam lobes 31 which are recognizable from predominantly dark background images based on image matrix elements or pixels with high light intensity values, the intensity distribution within that the beam lobes 31 reproducing pixel grayscale to, for example, a maximum of 255 at an 8-bit depth includes. In a first method step 201, a first sensor image is analyzed from a sequence of temporally successively detected image images, wherein the image matrix is read element by element with respect to the light intensity information respectively contained or scanned. In an adjoining method step 202, an intensity threshold value G is set in the first sensor image in order to define a light-dark boundary within the intensity curve of the first sensor image, which essentially serves to cause a reflection due to reflections on the interior wall of the measuring chamber to suppress. In a subsequent method step 203, recognition or identification of those image matrix elements P, of the first sensor image, whose associated stored light intensity information value reaches or exceeds the predetermined intensity threshold, takes place. The immediately following method step 204 is used to determine a relative injection rate of a defined number m of the previously known image matrix elements or pixel P, in the first sensor image according to the following equation:

In this case, with n (t) the relative injection rate in functional dependence on the time t, with P _j the jth pixel or image matrix element of a respective m image element detected by the image sensor, with G between high and contrast lower intensity values lying limit value, with j a summation index extending from 1 to m and with K _j a respective correlation factor. The correlation factor takes into account a light intensity information value I (P _j , t) recorded in the respectively assigned image matrix element and causes a normalization of the image matrix element contributions to n (t). In the summation, only those image matrix elements P _{j are} taken into account whose light intensity information values are greater than the limit value G or equal to the limit value G. In a further method step 205, the determined n (t) for the first sensor image is stored at time t as a measure of the injection rate corresponding to the optically detected cavitation image. A subsequent procedural step 206 increments an internal counter by one and initiates a return to step 201 to analyze a next sensor image at time t + At with the target, an associated injection rate (t + At) therein subsequent method steps 202 to 205 to determine. This procedure is repeated cyclically for the remaining sensor images of the sequence, so that finally there is an associated injection rate n (t) for each sensor image at a time t of a recording sequence. In a subsequent process step 207, the respective injection rate n (t) is displayed for all analyzed sensor images and correlated with injection rates from hydraulic measured-value acquisition, which are respectively coincident in time, on the basis of the pressure p and the speed of sound c.

FIG. 4A shows a flowchart 300 with the essential method steps of the evaluation method according to the invention in accordance with a second embodiment, which essentially serves to determine the beam propagation speed through the cavitation. In this case, an internal counter i is set to zero in an initialization step 301, whereupon in a further method step 302 the counter i is incremented by 1, ie i: = i + 1, in a process step 303 subsequent thereto, a first indexed sensor image Si a sequence or sequence of m detected sensor images Si, S ₂ , ..., Si, ..., S _m bear to bear or evaluate. In a subsequent method step 304, a light / dark intensity threshold is determined in those image matrix elements of the sensor image S currently being processed, which coincide with the dial outwardly extending ends of the beam lobes of an identified cavitation pattern correspond, the associated with this bright-dark intensity threshold image matrix elements or pixels approximately along ei nes imaginary - radially extending in the sensor image - circular ring with radius R, are arranged. The subsequent process step 305 serves a real beam propagation radius n in units of mm on the basis of the previously determined in step 304 and calculated in units of pixel pitch Ri, the magnification and the object size, which in Ausführungsbei play the nozzle diameter of the injector to be tested can be, calculate or determine. In a further method step 306, the beam propagation radius n calculated in this way is stored with the associated recording time t, of the current sensor image i as a pair of values. Since at least two temporally successive sensor images are to be analyzed in order to carry out a further evaluation step, a check is first made in an intermediate step 307 as to whether the counter i is greater than or equal to 2, with a return to step 302 with a count of i: = 1 to increment the count and to process the next sensor image and then perform steps 304-306, or else proceed to the next step 308. For in method step 308, the evaluation of two temporally successive sensor images Si _{+ i} and S, for the respectively determined value pairs, a quotient v is formed according to the following equation:

V (t _{i + i} ) = fc _{+ i -} ) Equation (2)

0

In this case, v (ti _{+ i} ) is the quotient, n is the beam radius determined for a respective sensor image, and t is the respective recording time of a sensor image, while n _{+ i is} the one for a time subsequently at time t _{+ i} characterized drew sensor image determined beam spread radius; thus equation (2) is derived from v = Ar / At. The quotient v (ti _{+ i} ) is a measure of the zir kulare propagation of - each existing at the radially outwardly pioneering ends of the beam lobes cavitation existing - light / dark intensity threshold between two temporally immediately successively detected sensor images or recording images and thus represents the Strahlausbreitungsgevindigkeit v in a cross-sectional plane, which is used to determine the corresponding jenden beam pulse p, taking into account the simultaneous hydraulic measurement of the injection quantity is used; FIG. 4B shows a projection 26 of two cavitation images taken in chronological succession, wherein the radius of the light-dark intensity threshold with respect to the ends of the beam lobes 31 is designated ri in the first cavitation image and r ₂ in the second cavitation image. In a subsequent method step 309, the respectively previously determined quotient is stored and displayed as a measure of the beam propagation velocity v in a cross-sectional plane and the beam impulse p calculated therefrom in a cross-sectional plane. A subsequent intermediate step 310 serves to check the current counter reading and, in the event that not all sensor images of a sequence have yet to be analyzed or evaluated, to return to step 302; otherwise, in a final step 311, a stop of this method block 300 and a return to the higher-level control method takes place.

4C shows a flowchart 300 ^' with the essential method steps of the evaluation method according to the invention according to a third embodiment, which serves essentially to control the beam propagation speed through the cavitation along the beam axis v _s (ti) in contrast to the evaluation method according to FIG. 4A to determine the beam propagation velocity in an image plane. For this purpose, an internal counter i and an internal counter j are each set to zero in an initialization step 301 ^' , ie i: = 0 and j: = 0, the counter i serving as a temporal index, taking individual image images or sensor images S for one To index certain image plane in terms of time, while the counter j is used as an index for the spatial indexing of the A zelbildaufnahmen S, ie a position or location of a respective Bildebe ne of corresponding single image recordings indexed. Following this, in method steps 302 ^' and 303 ^', first the counter i is incremented by 1, ie i: = i + 1, and then the counter j is incremented by 1, ie j: = j + 1, in order subsequently to be used in a further method step 304 ^' a correspondingly indexed sensor image S from the set of detected and stored sensor images herauszuselektieren and edit ing or evaluate. In accordance with an immediately subsequent method step 305 ^' , the radius Ry (in pixel spacing units) is determined on the basis of the image matrix elements of the sensor image Sy currently taken in processing in order to produce a real ray emission in the next method step 305 ^". distribution radius r, j in units of mm. In a further process step 306 ^' , the calculated beam spread radius r, j together with the associated recording time t and the image plane position X _{j of} the sensor image currently being processed are stored as value tuples (n _j , t ,, X _j ). In order to be able to analyze or compare at least two sensor images, in an intermediate step 307 ^', a check is made as to whether the counter is greater than or equal to 2, with a negative result returning to step 303 ^' to obtain the count for j increment by 1 and process the next sensor image, again performing steps 304 ^' through 306 ^' , or else proceed to next step 308 ^' . This method step 308 ^' serves as a test step to perform a query, if at two mutually for analysis associated sensor images for the corresponding beam propagation radii r, j and n, ji the Unglei chung r, j> n, ji is satisfied with the image plane maximum radius at the time of recording t, to find; if the query result is negative, a return is made to step 306 ^' for storing a value tuple (nj, t ,, Xj), while if the query result is positive, a transition is made to the next step 309 ^' , where the counter j is set to zero, ie j : = 0, whereupon in a next step 310 ^'a query is made for pairwise sensor images to be analyzed as to whether the counter i is greater than or equal to 2. If the query result is negative, a return is made to step 302 ^' , where a counter increment for i is performed, i: = i + 1, while if the query result is positive, a transition is made to step 311 ^' , in which the beam propagation velocity v _s (ti) along the Beam axis is calculated, as will be explained below. In a subsequent step 312 ^' then the calculated Strahlausbrei processing speed is stored together with the calculated therefrom Strahlausbrei processing pulse p _s . In a further step 313 ^' , a query is made as to whether a sequence has been completed or executed, ie the current counter i has the dimension m of the stored sensor images; with nega tive query result, there is a return to step 302 ^' with incrementing the counter i by 1, ie i: = i + l, while a positive query result, a transition to the last step 314 ^' takes place, in which a return to überge arranged control process takes place ,

FIG. 4D illustrates a graphical diagram as a basis for calculating the determination of the jet angle in step 311 ^' according to FIG. 4C. propagation velocity v _s (t). It is sketchy illustrated how a spray pattern ejected from an injector 15 spreads spatially depending on the time along its beam axis 18-3, with the spray pattern in a first state 18-1 at a time ^ and in a second state 18- 2 at a time t, _{i +} n based on the respective outer radius and n _{+ i} is indicated; These outer radii of the spray pattern states 18-1, 18-2 are associated with different image planes Z _{j + i} and Z _j + 3 spaced apart along the z axis of an x, y, z coordinate system. For this purpose, a rectangular triangle 18-4 in Koordina tensystem between the two states 18-1, 18-2 along the beam axis 18-3 constructable for the graphically illustrated embodiment, in which for the two cathets the relationships dz = Z _j +3 - Z _{j + i} equation (3)

and

dx = dr = n _{+ i} - n equation (4)

where dz is the differential of the variable z, dx is the differential of x, dr is the differential of r, and ds is the differential of the variable s.

For the hypotenuse then applies:

ds = jdr ¹ + dz ² equation (5);

This results in the beam propagation velocity v _s (ti _{+ i} ) by a set of Eq. 3 to 5 in the basic formula v _s (ti _{+ i} ) = ds / dt with dt = t, _{+ i} - t, a corresponding evaluation equation for v _s (t, ₊ i), which for the embodiment as a function f (zi ₊ 3, z, ₊ i, n _{+ i} , n, t _{+ i} , t,) can be represented.

4E shows a diagram to illustrate the temporal Divergenzverhal least one of an injector 15 ejected spray pattern, which - in contrast to the scheme shown in Fig. 4D - as Basis calculating the ge to determine the beam propagation speed in only one single image plane as shown in FIG. 4A and 4B is used. In this case, the spray pattern propagating along its beam axis 18-3 is identified in a first state 18-1 at time t1 and a second state 18-2 at time t1 _{+ i} on the basis of the respective outside radii n and n _{+ i} , which are resulting from their respective intersections with the image plane z ^' in an x, y, z coordinate system. This results in the calculation of the path difference dr between the two states 18-1 and 18-2, the relationship dr = n _{+ i} - n, wherein the time difference dt = ti _{+ i} - 1, is; for the calculation of v (ti _{+ i} ), therefore, the relation v (ti _{+ i} ) = dr / dt holds. FIG. 5A shows a cavitation image 30 which is optically detected by the device 10 according to the invention and, in addition to the beam lobes 31 symmetrically arranged in the central image area, which are identified by image matrix elements or pixels of the image sensor with high intensity values (shown in bright) at the image edges 33 whose associated image matrix elements also contain high intensity values and are attributable to undesired reflections of the light emitted from the inner wall of the measuring chamber. In order to reduce the influence of such reflections within the evaluation method according to the invention, an evaluation mask 32 is assigned to each sensor image or cavitation image in order to eliminate such image matrix elements during evaluation, ie to limit the evaluation region in the image matrix of the respective cavitation image accordingly. For this purpose, according to the presented in Fig. 5A Darge variant between the image center 34 remote from the beam lobes 31 and the reflections containing edge regions of the digitally scanned or recorded Kavitationsbilds a radially extending evaluation mask 32 is used, whose radius with respect to the image center 34 is greater than the radial extension of the beam lobes 31, but is dimensioned smaller than the radial position of the edge regions 33, so that the image matrix elements in the Randbe 33 of the image matrix in the evaluation according to equation (1) remain out of consideration and therefore only the image matrix elements within of the radius of the evaluation mask 32 are to be taken into account in the evaluation according to equation (1).

FIG. 5B shows a modified evaluation mask 35 which, unlike that of FIG. 5A, has a substantially star-shaped structure and is contoured so that each contour element of the star-shaped structure is assigned a respective beam lobe 31, so that each beam is closely framed, the respective gap between each zueinan the adjacent is delimited and the radial extent of each Konturenele element greater than the position seen in the radial direction of the end of the respec gene beam lobe 31, but significantly smaller than that seen in the radial direction Location of the edge regions 33 is dimensioned. As a result, image matrix elements of image areas which lie between the respectively adjacent beam lobes 31 and between the ends of the beam lobes and the image edges 33 remain in the evaluation according to equation (1), which in the evaluation is a Highlighting of beam-relevant image components compared to the image background causes.

5C shows a again modified evaluation mask 36, which - in contrast to the embodiments shown in FIGS. 5A and 5B - has a structure which is selectively associated with only a single beam lobe 31 in the cavitation image and the beam lobe 31 is framed in this way. the mask structure proceeds approximately from the origin of the beam lobe 31 and narrows the beam lobe narrowly at its outer edges up to its end, wherein the radial extension of the structure of the evaluation mask 36 is dimensioned to be slightly larger than the position of the end of the beam lobe 31 seen in the radial direction. As a result, in the evaluation according to equation (1), image matrix elements of image areas remain out of consideration, which lie clearly outside those image matrix elements which reflect the intensity distribution of the individual beam lobes 31. As a result of the selective application of such a mask structure to individual beam lobes 31 of a cavitation image, asymmetry effects, ie deviations of the intensity distributions of the individual beam lobes 31, can be quantitatively analyzed and evaluated with respect to one another with regard to the associated injection ports. Assess manufacturing tolerances and / or localize manufacturing defects.

6 shows a measurement diagram 40 in which measurement data 41 evaluated optically and evaluated by the method according to the invention as a measure of a normalized injection rate in each case functionally dependent on the time t running along the abscissa axis during an injection process and for comparison to a hydraulically detected and on a maximum of 1 normalized injection rate are plotted on the basis of a continuous measurement curve 42. The optically detected and evaluated according to the method according to the invention from the flow diagram 200 measured data 41 are divided into groups, each differing from each other with respect to the set intensity threshold un and are shown in Fig. 6 by different symbols, wherein for a first group, in the the associated measurement data are denoted by reference symbol L, only such pixels in the respective cavitation image with intensity values from a threshold of, for example, 150 in an 8 to 8 bit gray value depth, for example from 0 to 255, are taken into account in the count for a second group in which the associated measured data are denoted by reference symbol 0, only those pixels with intensity values above a threshold of 220, and for a third group, in which the associated measured data are denoted by reference symbol O, only those pixels with intensity values from a threshold of 250 are used. All three groups of the optically acquired and evaluated measured data 41 are, as shown in FIG. 6, close to each other and have along the time axis t an approximately bell-shaped distribution, the rising edge 44 corresponds to the beginning and the falling edge 44 ^' with the end of the injection process. The simultaneously hydraulically detected injection rate is shown along the ordinate axis as a continuous measurement curve 42, the injection rate being determined essentially as a function of the time profile of the measured pressure p (t) in the measuring chamber and the measured pressure-dependent sound velocity c (p) becomes. Both the measured data obtained according to optical recognition or sampling and the measuring curve acquired simultaneously at the same time are normalized with respect to the ordinate axis F (t) to a maximum of 1, in order to enable a direct comparison. Furthermore, Fig. 6 shows a substantial agreement between the time course of the optically obtained measurement data 41 and the course of the hydraulically gewonne NEN measurement curve 42. Also, the start of injection and the end of injection is - in annä mately temporal agreement with the simultaneously made hydraulic measurement Mes - clearly based the rising edge 44 and the falling edge 44 ^' determinable. The higher edge steepness in the optical detection or sampling in contrast to the hydraulic measurement is due to the fact that in the hydraulic measurement, a low-pass filter is used in the Meßelektronikein unit, which serves to filter out natural oscillations in the measuring chamber and as a side effect on the one hand for a clear flatter course in the flank area of the solid curve and on the other hand for measurement value scattering or measurement artifacts in between the two flanks 44, 44 ^' lie ing plateau region 45 provides.

Claims

claims

1. A method for characterizing the injection behavior of an injection valve for liquids with the following method steps:

- Injecting liquid through the injection valve (15) in a measuring chamber

(11)

- Injecting light into the measuring chamber (11) on the injection valve (15) as a spray pattern (18) ejected liquid,

Detecting and sampling temporally successive jet images which are produced by light reflected at phase boundaries of the spray nozzle (18) ejected from the injection valve (15) and imaged onto a recording device (12, 22) in order to obtain spatially resolved intensity distributions,

Evaluating the respective intensity distributions assigned to the detected and scanned beam images, wherein in the respective intensity distributions such image matrix elements are identified which contain image information associated with the imaged spray pattern, and a measure based on the respective image matrix elements identified and their time evolution for the injection behavior is determined.

2. The method according to claim 1, characterized in that as a measure of the injection behavior serving as a characteristic relative injection rate based on the following relationship

where n (t) is the relative injection rate functionally dependent on the time t, with G a threshold between high and significantly lower intensity values, and _{Pj is} a jth image matrix element of a respective beam detected and sampled by the receiver image, where j is a summation index extending from 1 to m and K _{j is} a respective correlation factor, where K _j takes into account a light intensity information value I detected in the respectively assigned image matrix element, whereby only such image matrix elements P _{j are} taken into account in the summation, their light intensity values are greater than the threshold G or equal the limit value G are to identify ter associated with the respective spray pattern Sprühmus associated image matrix elements.

3. The method according to claim 1 or 2, characterized in that the on acquisition device (12, 22) is set so that a cross-sectional plane of the ejected spray pattern (18) as a spray pattern (30) is shown in focus.

4. The method according to any one of claims 1 to 3, characterized in that recorded in temporally successive beam images different cross-sectional planes and scanned, in each case the focal length of the receiving device (12, 22) is changed and / or the receiving device (12, 22 ) is shifted with respect to its optical distance to the measuring chamber (11).

5. The method according to claim 4, characterized in that from the ver different cross-sectional planes at each time of injection a dreidi dimensional image of the spray pattern can be generated.

6. The method according to any one of claims 1 to 4, characterized in that as a measure of the injection behavior, a beam propagation speed in egg ner cross-sectional plane based on the following relationship

where v (t, _{+ i} ) is the beam propagation velocity, where i is an index for a respective beam image to be processed, n is a beam spread radius at time t, for an i-th beam image, and n _{+ i is} a beam spread radius time t, _{+ i} th a (i + l)-ray image are designated, wherein detects at least two consecutive spray patterns and evaluated by image matrix elements are identified in the i-th ray image which facing with outward ends of beam lobes of an imaged Sprühmus ters (18) correspond and are arranged approximately on an imaginary circular ring with a Strahlausbreitungsradius n, and in the (i + l) -th beam image image matrix elements are identified, which with the outward pointing En of beam lobes of the spray pattern then mapped ( 18) correspond and are arranged approximately on an imaginary circular ring with a beam spread radius n _{+ i} .

7. The method according to claim 5 or 6, characterized in that a beam propagation velocity along the beam axis from the dreidimen sional image of the spray pattern is determined.

8. The method according to claim 6, characterized in that a calibration of the Strahlausbreitungsradien takes place by an imaging relevant object size, preferably a nozzle diameter of the injection valve to be tested, and / or a magnification of the receiving device (12, 22) and / or a resolution of the Recording device (12, 22) is taken into account / be.

9. Method according to claim 1, characterized in that hydraulic measurements for determining a hydraulically obtained characteristic variable in the measuring chamber (11) are carried out simultaneously with optically detecting beam images, wherein optically obtained measured data correlate with hydraulically obtained measured data with respect to the characteristic become.

10. The method of claim 9, if appended to claim 6, 7 or 8, characterized in that a beam pulse is determined as a further characteristic, wherein the beam pulse from the optically obtained Strahlausbreitungsge speed in a cross-sectional plane v (ti _{+ i} ) or along the Beam axis and from a hydraulically obtained injection quantity by respective Produktbil tion is determined.

11. Apparatus for carrying out the method according to one of claims 1 to 10 with a measuring chamber, an illumination device for irradiating light via an optical access in the measuring chamber, a Aufnahmeein direction for detecting from the measuring chamber via the optical access zurückkommendem light and an evaluation , characterized in that the evaluation device has a data transmission connection to the receiving device (12, 22) in order to process and evaluate jet images detected and scanned by the recording device (12, 22), the evaluation device being in from the receiving device (12, 22). detected in intensity distributions of respective beam images such image matrix elements identified which an image spray pattern (18) associated Bildin- contain formations, and determined on the basis of the respectively identified image matrix elements and their time evolution, a measure of the injection behavior.

12. The device according to claim 11, characterized in that the receiving device (12, 22) along its optical axis by means of an associated

Positioning device (24, 25) is designed to be movable in order to change the optical path length between the receiving device (12, 22) and the measuring chamber (11).

13. The apparatus according to claim 11 or 12, characterized in that the

Recording device (12, 22) is designed as a digital camera in order to detect a spatially resolved Intensitätsver run for each detected and scanned beam image.