EP1630411B1 - Method for testing nozzles in internal combustion engines - Google Patents

Abstract

Method for testing fuel injection nozzles of combustion engines comprises using a fluid jet directed onto a pressure sensor for testing each nozzle. Preferred Features: The pressure in a defined surface region is determined using a pressure sensor. The pressure is determined over the surface region of the cylinder bore in the engine block or in the combustion chamber of the cylinder head.

Description

The invention relates to a method for testing nozzles of internal combustion engines according to the preamble of claim 1.

Internal combustion engines are usually equipped with fuel injectors. Modern internal combustion engines, in particular high-performance engines, furthermore have piston cooling nozzles which inject oil against the underside of the pistons, in particular into cooling channels or supply channels emanating from the underside of the pistons. These types of nozzles not only have to produce a jet of a certain geometry, in particular a certain cross-section, but the jet must also have a precisely defined direction so that the oil of the piston cooling nozzles reaches the respective cooling channel or supply channel at the bottom of each piston. Consequently, when testing both injection nozzles and piston cooling nozzles, it is particularly important to determine the jet geometry and the jet direction.

It has hitherto been known, in particular, to check injection nozzles in the cylinder head after installation, specifically before the cylinder head is mounted on the engine block. Only the function of the injectors is tested in a function test. From this it can only be deduced whether the injection nozzle is in order or not. However, the beam geometry and in particular the beam direction can not be determined in this known test. The same applies to piston cooling nozzles. With these it is particularly important, the Check beam direction to ensure that the emerging from the piston cooling nozzles jet of oil when mounted internal combustion engine and the right spot on the underside of the respective piston, in particular the piston cooling channel or feed channel hits. Such a method is known from DE 2 532 132 A1.

On this basis, the invention has the object to provide a method by which nozzles of internal combustion engines, in particular injectors and piston cooling nozzles, at least with respect to their beam direction, preferably also the beam geometry, can be easily and reliably tested.

A method for achieving this object has the features of claim 1. Accordingly, the examination of each nozzle, in particular of each injection nozzle or piston cooling nozzle, is carried out with a directed to at least one pressure sensor fluid jet. The direction of the fluid jet emerging from the nozzle to be tested can be determined with the at least one pressure sensor because, due to a predetermined positioning of the at least one pressure sensor, a signal is generated by the same only when the respective pressure sensor is hit. If the pressure sensor is hit only partially by the air jet emerging from the respective nozzle, this results in an attenuated signal, which also allows conclusions to be drawn about a deviating beam direction from the given direction. It is also possible to draw conclusions about the beam geometry from the intensity of the pressure signal picked up by the pressure sensor.

According to a preferred embodiment of the method according to the invention, a surface pressure sensor is used, which may also be formed from an array or grid of several individual pressure sensors. Consequently, if only one surface pressure sensor is mentioned below, this includes an array or grid of several pressure sensors.

From the respective surface pressure sensor, the pressure of the fluid jet emerging from the nozzle to be tested can be determined in a predetermined surface area, namely, it can be scanned. The test method according to the invention thus determines the point at which the test beam from the nozzle to be tested impinges on the area scanned by the surface pressure sensor (test surface). As a result, exact statements about the direction of the emerging from the nozzle to be tested fluid or Prüfstrahls are possible. The beam geometry of the test beam can be detected by the size and shape of the surface on which the fluid jet emerging from the nozzle generates a pressure signal on the surface pressure sensor. The pressure signal is three-dimensional image of the surface pressure sensor, the pressure value spatially displayed on a perpendicular to the test area. As a result, a pressure distribution of the test beam over the cross section in the region of the test surface, namely the plane of the surface pressure sensor, can be determined.

It is further provided with the pressure sensors, in particular surface pressure sensors, a pressure over the preferably entire surface area of a respective cylinder bore (in the case of testing the Kolbenkühldüse) in the engine block or (in the case of testing the injector) to determine a combustion chamber in the cylinder head. In this way, the largest possible surface area is available for testing the jet direction and preferably also the jet geometry of the fluid jet of the injection nozzle or piston cooling nozzle used for testing. In practice, the pressure over the entire cross-sectional area of the cylinder bore in the engine block or the combustion chamber in the region of the contact surface of the cylinder head on the engine block can be determined. As a result, a maximum meaningful examination of the direction and the geometry of the injection jet of injection nozzles and the cooling jet of piston cooling nozzles is possible.

According to a further embodiment of the invention, for checking piston cooling nozzles, the surface pressure sensor assigned to each piston cooling nozzle or cylinder bore is fastened to the side of the engine block facing the cylinder head above the respective cylinder bore during the test of the piston cooling nozzles. It is preferably tested simultaneously all the piston cooling nozzles of the internal combustion engine. Accordingly, in a six-cylinder internal combustion engine with one piston cooling nozzle per cylinder, six surface pressure sensors would be presently secured over the respective cylinder bore. To simplify the test, it is possible to attach all or only one group of surface pressure sensors to a common carrier, so that all or at least a plurality of surface pressure sensors can be attached to the engine block simultaneously and in the correct relative position to one another and also removed again. The surface pressure sensors are acted upon by the end of the test beam extending through each cylinder bore on the side of the engine block opposite the piston cooling nozzle.

In the examination of injectors is provided to assign each injector a surface pressure sensor, which is arranged on the plant side of the cylinder head on the engine block. The surface pressure sensor is then located in front of the combustion chamber, where it has the largest cross-section, because usually the surface of the combustion chamber on the plant side of the cylinder head on the engine block is greatest. It is also for each injector or each cylinder a separate surface pressure sensor assigned. If appropriate, the surface pressure sensors may be all or only partially associated with a common carrier.

According to a preferred embodiment of the method is covered by the respective surface pressure sensor, the entire opening of the combustion chamber on the contact side of the cylinder head on the engine block or the entire cylinder bore in the engine block. As a result, the greatest possible surface area of the cylinder bore or of the combustion chamber can be determined by the respective surface pressure sensor with respect to the impact and the cross section of the test beam emerging from the same for testing the respective nozzle.

The injection nozzles or piston cooling nozzles are preferably continuously pressurized with compressed air during the test and at least the location and the pressure of the compressed air jet emerging from the nozzles, and preferably also the pressure distribution across the cross section of the compressed air jet, are determined by the surface pressure sensors. This ensures a meaningful test of both piston cooling nozzles and injectors with regard to their function, the accuracy of the nozzle bore and above all the correct installation of the piston cooling nozzles in the engine block or injectors in the cylinder head. The compressed air allows a contamination-free cold test, without falsifying the test or measurement result in an incomprehensible manner.

During the preferably entire test period, a continuous compressed air jet is generated by the piston cooling nozzles or injection nozzles. As a result, the measurement can take place continuously over a certain period of time, and meaningful, namely stable measurement results over a certain period of time, can be achieved by recording the measurement result over time of the surface pressure sensors. If, during the test, there is no constant measurement result over at least a certain period of time, this indicates that the measuring device has errors. In this way, it can be seen that a test result which would indicate incorrect nozzles or a wrong installation of the same is not usable, because the test device and / or a measuring computer for the evaluation of the test result are faulty.

According to a preferred embodiment of the method, compressed air at room temperature is used to test both the piston cooling nozzles and the injectors. As a result, can be used for testing compressed air from the usually existing compressed air network without this compressed air must be treated in any way. The inventive method is characterized by the lowest possible consumption costs.

It is further provided to use air at a pressure of 1 to 5 bar, preferably 2 to 3 bar, for testing both the injection nozzles and the piston cooling nozzles. Even air with such pressure is available in the usual compressed air supply network, so that in this respect, the process is inexpensive to carry out. Due to the use of area sensors or an array or grid of a multiplicity of pressure sensors, air with a pressure of between 1 and 5 bar, in particular 2 to 3 bar, is sufficient for testing the piston cooling nozzles and injection nozzles in order to use the pressure sensors used, in particular surface pressure sensors. obtain meaningful measurement results. The air pressure may be at the lower limit of said pressure range, when the distance of the nozzle to be tested to the surface pressure sensor is relatively small, as is the case for example in the examination of injectors in the cylinder head. If the distance of the piston cooling nozzles to the surface pressure sensor is greater, especially in long-stroke internal combustion engines, air with a pressure in the upper range of the specified ranges can be used to test the piston cooling nozzles.

Fig. 1

einen schematischen Vertikalschnitt durch einen Kolben mit einem Kolbenkühlkanal,

Fig. 2

eine schematische Ansicht eines Teils eines Zylinderkopfs im Bereich einer Zylinderbohrung mit einer dieser zugeordneten Kolbenkühldüse, und

Fig. 3

eine schematische Ansicht eines Teils eines Zylinderkopfs im Bereich einer Einspritzdüse.

Two preferred embodiments of the invention will be explained in more detail with reference to the drawing. In this show:

Fig. 1

a schematic vertical section through a piston with a piston cooling channel,

Fig. 2

a schematic view of a portion of a cylinder head in the region of a cylinder bore with a piston cooling nozzle associated therewith, and

Fig. 3

a schematic view of a portion of a cylinder head in the region of an injection nozzle.

1 and 2, the inventive method will be explained in connection with the examination of piston cooling nozzles 10 of internal combustion engines. Each cylinder 12 or each pair of adjacent cylinders 12 of the internal combustion engine is associated with a piston cooling nozzle 10. In a six-cylinder internal combustion engine, six piston cooling nozzles 10 are thus present. These are tested simultaneously, in the functional test before the complete assembly of the internal combustion engine, in particular when the pistons 11 are not yet mounted in the cylinder bores 13 of the engine block 14.

This has in the interior via a preferably annular cooling channel 15. This is arranged in the upper region of the piston 11, namely surrounds about a part of the combustion chamber forming combustion chamber recess 16 which from a top 17th of the piston 11 goes out. At the location of the cooling channel 15 and cooling coils or more complex cooling chambers (built-piston) can be provided. The supply of the cooling channel 15 with cooling liquid, in particular oil, is effected by a mostly vertical, rectilinear supply channel 18. The supply channel 18 is open in the region of the underside 19 of the piston 11 and opens with its upper end at a point in the cooling channel 15 (FIG ).

The piston cooling nozzle 10 is fixed to a lower side of the engine block 14. The piston cooling nozzle 10 may be configured to include a central coolant supply member 20 that is supplied with oil from the oil pan from the crankcase. Then, the piston cooling nozzle 10 is screwed to the coolant supply part 20 under the engine block 14. From the coolant supply part 20 branches off in the embodiment shown two opposite pipe sections 21, which are guided to the underside of adjacent cylinder 12. With a piston cooling nozzle 10, two pistons 11 in different cylinder bores 13 are then simultaneously, but separately, supplied with cooling fluid, in particular oil. Each tube section 21 of the piston cooling nozzle 10 is shaped so that a nozzle-like cooling nozzle end 22 projects from below into the respective cylinder 12, in such a way that coolant is ejected eccentrically vertically upward from the cooling nozzle end 22 in the direction parallel to the cylinder center axis 23 under the piston 11 , This takes place in such a way that the coolant jet emerging from the cooling nozzle end 22 of the piston cooling nozzle 10 is directed precisely into the coolant supply channel 18, also running parallel to the cylinder central axis 23, for cooling liquid 15. The assembly of the piston cooling nozzle 10 under the engine block 14 must then be such that the emerging from the cooling nozzle end 22 cooling oil from below into the feed channel 18 in the piston 11. The oil jet must also have a geometry, in particular a beam cross-section, which is matched to the diameter of the feed channel 18, so that at least a majority of the cooling oil, which is injected from the cooling nozzle end 22 from below against the piston 11, passes into the feed channel 18 , Alternatively, the piston cooling nozzle can also be designed so that it supplies only a single piston 11 with cooling oil. Then, a separate piston cooling nozzle is provided for each piston 11 or cylinder.

According to the method according to the invention, the positioning and preferably also the geometry or the cross section of the coolant jet is tested in the cold test prior to assembly of the internal combustion engine, in particular in the case of the piston 11 not yet used in the engine block 14. During this test, all piston cooling nozzles 10 of the internal combustion engine are fed simultaneously and continuously with a pressurized fluid. The fluid then exits through each end of the cooling nozzle 22 and flows through each cylinder bore 13 in the engine block 14 of the internal combustion engine from bottom to top. As a fluid is preferably compressed air into consideration. The pressure of the air is 1 to 5 bar, preferably 2 to 3 bar. Specifically, the pressure of the air is about 2½ bar. It is used such air having an ambient temperature. The air is therefore neither cooled to the ambient temperature nor heated. Such compressed air can be taken from a usually existing pressure medium network.

The examination of the position of each test air jet and in particular its geometry, especially its cross-section, takes place in a preferred embodiment of the invention by a surface pressure sensor. As a result, the prevailing pressure is determined at least qualitatively, preferably also quantitatively, at each point of the surface pressure sensor. The surface pressure sensor can also be formed from a grid or array of many individual pressure sensors, which uniformly scan the pressure measuring surface thus formed over a certain area due to a uniform grid-like distribution. This makes it possible to determine the location at which the beam impinges on the measuring surface of the surface pressure sensor or the grid of a plurality of identical pressure sensors with the test fluid, in particular compressed air jet. In addition, the surface pressure sensor can be used to determine the cross section of the test beam, in particular test air jet, with which it impinges on the measuring surface of the surface pressure sensor, from which conclusions can be drawn about the beam geometry of the test beam or the test air jet.

Each of the identical surface pressure sensors 24 is dimensioned so that it covers a cylinder bore 13 of the engine block 14 over the entire surface, preferably with a circumferential overlap of the cylinder head 28 facing top 25 of the engine block 14. Thus, the surface pressure sensor 24 is located on the cooling nozzle end Due to the complete coverage of the top of the cylinder bore 13 by the surface pressure sensor 24, this can detect the pressure of emerging from the respective cooling nozzle end 22 and upward test air jet in the entire region of the cylinder bore 13.

Each individual cylinder bore 13 associated surface pressure sensor 24 is releasably secured to perform the method according to the invention on the respective cylinder bore 13 on the upper side 25 of the engine block 14. The purpose of a fastening device, not shown in the figure, which is designed so that it can be easily attached to the top 25 of the engine block 24 and just as easy to solve this again. Alternatively, it is conceivable to design the fastening device in such a way that it locks all identically formed surface pressure sensors 24, which are assigned to the cylinder bores 13 arranged in a row in the engine block 14, at the same time detachably on the upper side 25 of the engine block 14. In this way, all surface pressure sensors 24 for a number of cylinder bores 13 in the engine block 14 are simultaneously fixed positionally above the respective cylinder bore 13 by a single assembly process. After the test, all surface pressure sensors 24 can be released simultaneously from the upper side 25 of the engine block 14 at the same time.

The method according to the invention for preferably simultaneous testing of all piston cooling nozzles 10 of an internal combustion engine in the cold test proceeds as follows:

After all piston cooling nozzles 10 are mounted on the underside of the engine block 14, but still no cylinders 12 are in the cylinder bores 13 of the engine block 14, a surface pressure sensor 24 covering this over the entire surface of the cylinder block 14 is attached to the top 25 of the engine block 14 above each cylinder bore 13. The surface pressure sensors 24 may be fastened together or individually to the top 25 of the engine block 14 for performing the test. All surface pressure sensors 24 are permanently provided with leading to a preferably single, common test computer test leads. If appropriate, the energy supply of the surface pressure sensors 24 can also take place via this. All cooling nozzles 10 are now subjected to a test fluid, in particular compressed air. For this purpose, the coolant supply part 20 of each piston cooling nozzle 10 is preferably connected to a compressed air supply.

After the compressed air outlet has been released from the compressed air supply, serving for checking compressed air flows out of the cooling nozzle ends 22 of the piston cooling nozzles 10. When the piston cooling nozzles 10 are intact and correctly mounted, a thin compressed air jet flows parallel to the cylindrical central axis 23 in the direction of the surface pressure sensors 24 on the upper side 25 of the engine block 14. The respective surface pressure sensor 24 now determines the point at which the test air jet touches the surface pressure sensor 24 incident.

On the basis of the point at which the respective compressed air or Prüfluftstrahl on the surface pressure sensor 24, preferably the underside of the same, impinges, it can also be determined whether the Prüfluftstrahl is mounted correctly. Furthermore, the pressure with which the test air jet impinges on the surface pressure sensor 24 can be determined. It can be concluded from this whether the piston cooling nozzle 10, in particular the cooling nozzle end 22 forming an outlet of the test compressed air from the piston cooling nozzle 10, is produced correctly. In addition, the shape and size of the surface with which the test air jet impinges on the surface pressure sensor 24, the geometry of the same can be determined.

FIG. 3 illustrates the use of the method according to the invention for testing injection nozzles 26 in the cold test. The test is carried out after all injectors 26 and all spark plugs 27 are mounted in the cylinder head 28 of the internal combustion engine. In this case, the cylinder head 28 with the injectors 26 and the spark plugs 27 but not yet placed on the engine block 14. The upper side 25 of the engine block 14 facing bottom 29 of the cylinder head 28 is thereby still freely accessible. Preferably, the injectors 26 are not yet connected to fuel supply lines. Also, the spark plugs 27 need not yet be connected to ignition wires of the ignition system.

All injectors 26 are simultaneously tested in a functional test. Accordingly, the injectors 26 are not supplied with fuel for testing, but with a test fluid, in particular compressed air, and at room temperatures at a pressure between 1 and 5 bar, preferably 2 to 3 bar. The compressed air can come from a standard compressed air supply.

In order to test the injection nozzles 26, a surface pressure sensor 30 arranged in the region of each combustion chamber 31 on the underside 29 of the cylinder head 28 is likewise used. The surface pressure sensor 30 may be configured and operate like the above-described surface pressure sensor 24. In this respect, reference is made to the statements in connection with the examination of piston cooling nozzles 10 described with reference to FIGS. 1 and 2.

Below each of the bottom 29 of the cylinder head 28 located combustion chamber 31, a surface pressure sensor 30 is arranged. The surface pressure sensor 30 is dimensioned so that it completely covers the respective combustion chamber 31, preferably circumferentially overlapping an edge region of the underside 29 of the cylinder head 28 about the combustion chamber 31.

The surface pressure sensors 30, which are preferably identical to one another, are connected to the lower side 29 of the cylinder head 28 individually or jointly or in groups by a fastening device (not shown). When checking the injection nozzles 26, the same procedure is used in principle as when checking the piston cooling nozzles 10.

The injectors 26 mounted in the cylinder head 28 are tested in a cold test before the cylinder head 28 is connected to the engine block 14. For this purpose, a separate surface pressure sensor 30 is fixed from the still freely accessible underside 29 forth below each combustion chamber 31. Either all or groups of several surface pressure sensors 30 are arranged together, ie simultaneously, under the underside 29 of the cylinder head 28 or the surface pressure sensors 30 are fastened individually one after the other. In this case, each surface pressure sensor 30 closes a combustion chamber 31.

The injectors 26 are checked simultaneously. For this purpose, each injector 26 continuously supplied during the testing process, so uninterrupted, with compressed air. The compressed air emerging from each injection nozzle 26 forms a test air jet which impinges on the respective surface pressure sensor 30 opposite the injection nozzle 26. The surface pressure sensor 30 measures the emerging from the injector 26 compressed air or Prüfluftstrahl. In this way, the surface pressure sensor 30 can firstly determine the location of the impact of the test air jet. On the other hand, the pressure with which the test air jet impinges on the surface pressure sensor 30 and the shape and dimension of the test air jet are determined.

LIST OF REFERENCE NUMBERS

10

piston cooling

11

piston

12

cylinder

13

bore

14

block

15

cooling channel

16

Cavity combustion chamber

17

top

18

feed

19

bottom

20

Coolant supply part

21

pipe section

22

Cooling nozzle end

23

Cylinder center axis

24

Surface pressure sensor

25

top

26

injection

27

spark plug

28

cylinder head

29

bottom

30

Surface pressure sensor

31

combustion chamber

Claims (10)

1. A method for checking nozzles of internal-combustion engines, with the nozzles being installed and in particular checked for their correct installation and/or operation prior to the complete assembly of the respective internal-combustion engine, characterized in that each nozzle is checked with a jet of fluid medium directed toward at least one pressure sensor.
2. The method according to Claim 1, characterized in that the pressure is determined in a defined surface region, in particular by employing a surface pressure sensor (24, 30) or a surface pressure sensor (24, 30) formed by an array or grid comprising a plurality of individual pressure sensors.
3. The method according to Claim 1 or 2, characterized in that the pressure across a surface region of a respective cylinder bore (13) in the engine block (14) and/or in the combustion chamber (31) of a cylinder head (28) is determined preferably with the surface pressure sensors (24, 30).
4. The method according to one of the previous Claims, characterized in that, for the checking of piston cooling nozzles (10), the pressure sensors, in particular surface pressure sensors (24), are detachably affixed above the respective cylinder bore (13) on the side of the engine block (14) facing the cylinder head (28).
5. The method according to one of the previous Claims, characterized in that, for the checking of injection nozzles (26), the pressure sensors, in particular the surface pressure sensors (30), are detachably arranged on the bearing side of the cylinder head (28) on the engine block (14) in front of or below the respective combustion chamber (31) at the cylinder head (28).
6. The method according to one of the previous Claims, characterized in that the surface pressure sensor (24, 30) covers the preferably entire opening of the combustion chamber (31) of the cylinder head (28) or covers the entire cylinder bore (13) in the engine block (14).
7. The method according to one of the previous Claims, characterized in that compressed air is applied to the piston cooling nozzles (10) or to the injection nozzles (26) for the checking operation, and that the pressure sensors, in particular the surface pressure sensors (24, 30), determine the position, the pressure and/or the geometry of the compressed air jet emitted by the piston cooling nozzles (10) or the injection nozzles (26).
8. The method according to one of the previous Claims, characterized in that, during the check, preferably during the entire duration of the check, a continuous, uninterrupted jet of compressed air is generated by the piston cooling nozzles (10) or the injection nozzles (26).
9. The method according to one of the previous Claims, characterized in that compressed air at approximately room temperature is employed for checking the piston cooling nozzles (10) or the injection nozzles (26).
10. The method according to one of the previous Claims, characterized in that air compressed at a pressure of 1 to 5 bar, preferably 2 to 3 bar, is employed for checking the piston cooling nozzles (10) or the injection nozzles (26).

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