A TESTING DEVICE FOR FUEL INJECTION VALVES

The present invention relates to a device for testing fuel injection valves and related parts thereof.

In fuel injection systems of internal combustion engines, the pressures can be very high, even up to 6000 bars. Before the use of the fuel injection valve, a pressure test is applied to the fuel injection valve and its interior parts. A leakage in a fuel injection system causes a serious hazard both due to the high pressure of the fuel and the fire risk. During the high pressure test of the fuel injection valve, the connection block in which the injector and related parts attached can be cracked due to the high stress occurred in the connection portions.

Parts of the common-rail injection system need to be tested by a pressure testing device, and their fatigue limit is examined. In the prior art, an adaptor is used to hold the testing parts which are attached to the high pressure connection block wherein high stress surfaces occurs at the interface of the adaptor and connection block which result a crack on the connection block. There is a need for increasing the lifetime of testing device by eliminating cracking possibilities.

The present invention relates to a testing device for parts to be tested of a fuel injection valve of an internal combustion engine, comprising: at least one connection block having a plurality of branch holes communicated with each other through a flow passage, said connection block further having an inlet port through which pressure medium enters and an outlet port through which said pressure medium exits; said inlet port and the outlet port in communication with the flow passage; at least one adaptor for holding the part to be tested of the fuel injection valve, said adaptor being arranged to be detachably attached to the branch hole. Said testing device further comprises an alignment member for alignment and self-centering the adaptor wherein said alignment member is placed between the connection block and the adaptor so as to transfer the pressure medium from the connection block to the adaptor through an interior passageway. Said alignment member substantially improves the connection of the adaptor and the connection block, thus, prevents cracking occurrence for a prolonged period of time. The alignment member helps for better alignment of the adaptor within the connection block and ensures a self-centering of the adaptor.

In a possible embodiment, the alignment member has a first portion in the form of a frusto-conical arranged to match a hollow taper surface of a connection block. The first potion has a taper angle (a) of about between 45° and 70°, preferably 55° and 65°. Thus, less stress concentration between the alignment member and the connection block is obtained.

In a possible embodiment, the alignment member has a second portion in the form of a frusto-conical arranged to match a corresponding inlet hole of the adaptor. Further, the second portion has a taper angle (a) of about between 45° and 70°, preferably 55° and 65°. Thus, less stress concentration between the alignment member and the adaptor is obtained.

In a possible embodiment, the first portion has a chamfered end formed on the periphery of the first portion as inclined. Thus, a lower stress concentration is provided at the chamfered end.

In a possible embodiment, the connection block has four branch holes each in communication with the flow passage for testing more than one part of the fuel injection valve at the same time. Thus, a compact and efficient testing device is obtained.

In a possible embodiment, an induced plastic transformation is generated on the hollow taper surface by autofrettage processing. Thus, the compression residual stress is decreased.

In a possible embodiment, the branch hole has at least a portion in the interior surface which is threaded that matches with a corresponding threaded portion of the adaptor. The adaptor can thus be safely connected to the connection block. The figures, whose brief explanations are herewith provided, are solely intended for providing a better understanding of the present invention and are as such not intended to define the scope of protection or the context in which said scope is to be interpreted in the absence of the description.

FIG. 1 is a perspective view of an adaptor for attaching the fuel injector and related parts to a testing device according to the present invention.

FIG. 2 is a cross-sectional view of the adaptor shown in FIG. 1

FIG. 3 is a perspective view of an alignment member arranged to be used within an adaptor according to the present invention.

FIG. 4 is a cross-sectional view of the alignment member shown in FIG. 3.

FIG. 5 is a perspective view of a connection block according to the present invention.

FIG. 6 is a cross-sectional view of the connection block shown in FIG. 5.

FIG. 7 is a cross-sectional view of a testing device in which an adaptor and an alignment member are attached to a connection block according to the present invention.

FIG. 8 is a perspective view of a testing device shown in Fig. 7.

FIG. 9 is a cross-sectional view of a testing device in which an adaptor and an alignment member are attached to a connection block according to the present invention, showing a contact area of the alignment member to the connection block.

A-Detail shows the contact area of the alignment member to the connection block in detail which is taken from fig.9. FIG. 10 is a cross-sectional view of a testing device in which an adaptor is attached to a connection block according to the prior art, showing a contact area of the adaptor to the connection block.

B-Detail shows the contact area of the adaptor to the connection block in detail which is taken from fig.10.

The present invention proposes a testing device (40) for parts to be tested of a fuel injection valve of an internal combustion engine, comprising: at least one connection block (30) having a plurality of branch holes (32) communicated with each other through a flow passage (39), said connection block (30) further having an inlet port (36) through which pressure medium enters and an outlet port (34) through which said pressure medium exits; said inlet port (36) and the outlet port (34) in communication with the flow passage (39); at least one adaptor (10) for holding a part to be tested of the fuel injection valve, said adaptor (10) being arranged to be detachably attached to the branch hole (32). Said testing device (40) further comprises an alignment member (20) for alignment and self-centering the adaptor (10) wherein said alignment member (20) is disposed between the connection block (30) and the adaptor (10). The testing device (40) can have a pressure sensor which sense the pressure of the medium that comes from the outlet port (34) of the connection block (30). Further, the testing device (40) may have a pressure supply device, which sends the medium to the connection block (30) from the inlet port (36). In a possible embodiment, the connection block (30) has four branch holes (32) each in communication with the flow passage (39) for testing more than one part of the fuel injection valve at the same time. When the one or more than one of the branch holes (32) are not in use, these branch holes (32) are closed with a corresponding stopper-like adaptor. Further, more than one connection block (30) arranged to be on top of each other, when more than one connection block (30) are placed on top of each other, the channels thereof are aligned with respect to each other, and the connection blocks (30) are fastened with each other by fastening means which extends through a fastening hole (33) of the connection block (30). In a possible embodiment, the connection block (30) can include four fastening holes (33) as shown in Fig. 5. Said testing device (40) mainly comprises at least one connection block (30) with a plurality of branch holes (32) into which an adaptor (10) can be attached for holding parts to be tested of a fuel injector. Referring to the Fig. 7 and 8, the adaptor (10) allows attachment of the fuel injector parts and prevents the said parts from falling out of the connection block (30). The adaptor (10) can be used as a nut, which is attached to the connection block (30) by means of threads.

According to the present invention, the alignment member (20) is used for better alignment of the adaptor (10) within the connection block (30) and ensures a self- centering of the adaptor (10). The alignment member (20) has a first portion (23) as shown in Fig. 3 which serve for sealing against a hollow taper surface (31) of a branch hole (32) of the connection block (30). A sealing area is provided peripherally on the contact area of the alignment member (a) to the hollow taper surface (31) of the branch hole (32), especially sealing area is formed at an end of the first portion (23). Upon the securement of the adaptor (10) to the connection block (30), the first portion (23) and the second portion (24) of the alignment member (20) are situated against the hollow taper surface (31) of the branch hole (32) and a taper inlet port (11) of the adaptor (10), respectively, as shown in FIG. 7. The alignment member (20) has a flattened portion (29) at the junction of the first and second portions (23, 24), as shown in Fig. 4. A non- autofrettage area is formed on the branch hole (32). The first portion (23) has a chamfered end (231) formed on the periphery of the first portion (23) as inclined. Thus, a lower stress concentration is provided at the chamfered end (231).

The first portion (23) can be formed as a frusto-conical shape that matches the hollow taper surface (31), with a taper angle a of about between 45° and 70°, preferably 60°, as shown in Fig. 6. In a similar way, the alignment member (20) further comprises a second portion (24) which bears the taper inlet port (11) of the adaptor (10), when in use. The second potion (24) has a taper angle (a) of about between 45° and 70°, preferably 55° and 65°. The second portion (24) of the alignment member (20) is preferably in the form of the frusto-conical, which can be same as the first portion (23), which is shaped and dimensioned with respect to the taper inlet port (11) for sealing pressing the alignment member (20) against the connection block (30). The adaptor (10) comprises a first portion (13) and a second portion (14) with, preferably, screw threads formed on the outer surfaces thereof. The first portion of the adaptor (13) being arranged to be at least partly inserted into the branch hole (32) and the second portion of the adaptor (13) is arranged to hold a part of the fuel injection valve to be tested.

The adaptor (10) can be screwed on to a male screw thread on the connection block (30) in the usual manner. Further, the adaptor (10) could also be a plate or a block or a similar part, which is attached to the connection block (30). The branch hole (32) has at least a portion in the interior surface which is threaded that matches with a corresponding threaded portion of the adaptor (10). The adaptor (10) has an inner channel (12) as a through hole which is in communication with the flow passage (39) of the connection block (30) through the interior passageway (22) of the alignment member (20) in which high pressure medium axially flows. Said interior passageway (22) of the alignment member (20) is formed as a channel with an inlet and outlet ports having chamfered entrance portions. During production of the alignment member (20), a honing process is applied to the interior passageway (22) to decrease the surface roughness and increase the fatigue strength. In the prior art, the adaptor (10) is used without any alignment means that causes high stress on the connection block (30). The adaptor (10) is adapted to the connection block (30) with a 50-60 Nm torque in the prior art. As shown in fig.10 and B Detail, there is a smaller contact area as a contact area of the adaptor (b) to the hollow taper surface (31). With the present invention as shown in fig.9, there is a larger contact area as a contact area of the alignment member (a) between the alignment member (20) and the connection block (30).

In the prior art, there is a non- autofrettage area at the seat of the branch hole (32) of the connection block (30). With the invention, the non- autofrettage area is the hollow taper surface (31). The hollow taper surface (31) has low strength, which is not exposed to high pressure during test by changing the sealing position according to the prior art. The sealing is provided away from the flow passage (39) in the prior art but in the present invention, the sealing is provided very close to the flow passage (39). By use of the alignment member (20) in the invention, less force is needed for tighter and lower stress occurred in the contact area as well. For example, 30 Nm torgue is applied during mounting of the adaptor (10). Further, said alignment member (20) helps to obtain homogenous stress distribution between the connection block (30) and the adaptor (10) which helps to decrease crack occurrence on the connection block (30).

At the branch holes (32) of the connection block (30) an induced plastic transformation can be generated on the hollow taper surface (31) by autofrettage processing, and the compression residual stress is decreased. When the testing process is done, the part to be tested shows excellent internal pressure fatigue resisting characteristic.

List of reference signs

10. Adaptor

11. Taper inlet port

12. Inner channel

13. First portion of the adaptor

14. Second portion of the adaptor

20. Alignment member

22. Interior passageway

23. First portion

231. Chamfered end

24. Second portion

29. Flattened portion

30. Connection block

31. Hollow taper surface

32. Branch hole

33. Fastening hole

34. Outlet port

36. Inlet port

39. Flow passage

40. Testing device

a Taper angle

a: Contact area of the alignment member b: Contact area of the adaptor