APPARATUS AND FIXTURE FOR USE IN GRINDING THE NEEDLE TIP AND THE NEEDLE SEAT IN A FUEL VALVE

Abstract: An apparatus for use in grinding the needle tip and seat in the needle housing of a fuel valve includes a grinding pin (1) and a holder (4) for the grinding pin. The holder (4) is shaped and dimensioned to be guidingly received within the needle bore (45) of the needle housing. The grinding pin (1) has a first conical end (2) adapted for the seat, and a second hollow conical end (3) adapted for the needle tip. Advantageously the grinding pin is a disposable grinding pin made of hardened steel. A fixture for fixing the needle housing (34) when using the apparatus is also described.

Description: Apparatus and fixture for use in grinding the needle tip and the needle seat in a fuel valve The invention relates to an apparatus for use in grinding the needle tip and seat in the needle housing of a fuel valve. The invention also relates to a fixture for fixing the needle housing when using the new apparatus. A needle housing in a fuel valve has a needle bore for re- ceiving a needle. Uppermost or at the top the needle hou¬ sing has a ground surface from which an inclined bore leads down to a ring-shaped space located at the inner end of the needle bore. At this location there is provided a seat in¬ tended for sealing against the needle tip. The sealing face of the needle tip against this seat should be on the lar¬ gest diameter of the needle tip and be as narrow as pos¬ sible in order to obtain a good atomization of the fuel which is supplied through the inclined bore as mentioned above. To obtain this desired narrow sealing face the needle tip and seat must be ground with an angular diffe¬ rence of 0.5 - 1 . The invention has been developed in con¬ nection with the desire and need of being able to perform this grinding in a rational and automated way, and in this connection there is aoccording to the invention provided an apparatus which is characterized in that it comprises a grinding pin and a holder for the grinding pin, the holder being shaped and dimensioned to be guidingly received in the needle bore of the needle housing and the grinding pin having a first conical end adapted for the seat and a se- cond hollow conical end adapted for the needle tip. Preferably the grinding pin is made for single use, for ex¬ ample from hardened steel. For the purpose of grinding the needle, the holder is ad¬ vantageously provided with a split ring placed in a circum- ferential groove, the ring having a diameter a little lar¬ ger than the needle bore, with an axial stopper pin in the holder entering the opening of the split ring, the grinding pin and holder having cooperating elements for locking with a view towards relative rotation. Because the split ring has a diameter a little larger than the needle bore, it will attain a slight tensioning against the wall of the needle bore when the holder is inserted in- to the needle bore. Before the holder is put into the needle bore, the grinding pin is placed in the holder whereby the mentioned cooperating elements are caused to interlock. The holder with the grinding pin is inserted in¬ to the needle bore until the conical end of the grinding pin, which protrudes from the holder, bears against the seat in the needle housing. The needle 'housing is fixed in a suitable way in a grinding machine, and the needle which is to be ground is inserted into the needle bore such that the needle tip enters the hollow conical end of the grin- ding pin. Then, when the needle is brought into rotation, the holder firstly will try to follow the rotational move¬ ment. The stopper pin mentioned, however, will bear against one of the ends at the opening of the split ring and thus act on the split ring to expand it, whereby the holder will be locked in the needle bore. This will also lock the grin¬ ding pin. Advantageously the ends at the opening of the split ring can be tapered such that they converge in an outward radial direction, thus to form inclined flanks for cooperation with the stopper pin. The mentioned cooperating elements may advantageously com¬ prise a locking pin and a locking groove. The locking groove may advantageously have the shape of a bayonet groove. Fuel valves with a small difference between the diameter of the needle bore and the largest seat diameter will require an embodiment of the grinding pin as two separate parts to attain a step-down, such that there is attained room for the expansion ring and the stopper pin. Advantegously there may in a circumferential groove in the holder be mounted an O-ring. This O-ring contributes to the beginning locking of the holder and furthermore also serves for sealing, a function whose purpose will be explained in further detail below in connection with the new fixture. As mentioned the invention also relates to a fixture for fixing the needle housing when using the apparatus accor¬ ding to the invention, and such a fixture is according to the invention characterized by a bottom plate with a blind bore for receiving the nozzle part of the needle housing, with an O-ring to be laid in therebetween, with a bore for the supply of compressed air to the room within the blind bore under the nozzle part, and with a crossbar which can be mounted to the bottom plate abutting the top of the needle housing, with a seal to be laid in therebetween sea¬ ling the fuel supply bore in the needle housing. Such a fixture offers advantages. The needle housing is placed in the fixture, with the nozzle part placed in the blind bore. The O-ring will seal between the nozzle part and the blind bore. The needle housing is fixed by means of the crossbar while the mentioned seal, preferably a ring seal, is caused to seal against the fuel supply bore, that is, the opening of this bore at the top of the needle hou¬ sing. Fixed in the fixture, the grinding is performed by coupling the fixture to a suitable grinding machine. When the grinding is finished, compressed air is supplied to the room in the blind bore under the nozzle part. The pressure propagates through the nozzle openings and will "shoot up" the grinding pin and the holder. This assembly, consisting of the grinding pin and the holder, can be caught above the top of the needle housing with the palm of the hand. The assembly will float on the stream of air and will be easy to catch. To obtain this blowing-out the holder is provided with the O-ring mentioned before. Advantageously there may also be provided and O-ring between the grinding pin and the holder such that the pin is "floating" und thus self- centering. When grinding the seat of the needle housing the grinding pin is exchanged into a suitable holder for this purpose. This holder is shaped for interlocking with the grinding pin, in the same way as the holder which is used for grin¬ ding the needle tip, but otherwise, it is just shaped as a cylindrical body which can be guidingly received in the needle bore of the needle housing. The holder is provided with means, for example and end projection, for coupling to a grinding machine such that the whole assembly can be put into rotation for grinding the seat. Here the O-ring holds the grinding tip in place (a kind of locking) . The invention will be more closely described with refernce to the drawings, wherein: Fig. 1 shows an upright partial section of a typical grin¬ ding pin and holder for grinding the needle in a fuel valve, shows a top view of the embodiment of fig. 1, shows a longitudinal section of a slightly diffe¬ rent embodiment of a holder, shows a top view of the holder of fig. 3, shows the lower part of a two-part grinding pin, shows a top view of fig. 5, shows a longitudinal section of the upper part of the two-part grinding pin, fig. 8 shows a top view of fig. 7, fig. 9 shows a pin with a holder for grinding the seat, fig. 10 shows a section of a fixture according to the in- vention, with a holder and grinding pin for grin¬ ding the needle tip, and fig. 11 shows a top view of the crossbar and slit. In fig. 1 there is shown a grinding pin 1 shaped with a first conical end 2 and a second hollow conical end 3. The first conical end is adapted for the seat of a fuel valve while the second hollow conical end 3 is adapted for the needle tip. Thus it is indicated in fig. 1 that the first conical end should have an angle of 60° while the hollow conical end should have an angle of 60.8°. The holder 4 is, in order to ease the shaping of a bayonet groove 5, embodied as an inner casing 6 and an outer, shor¬ ter casing 7 whereby there is formed a groove 8 uppermost in the holder, wherein there is placed an expansion ring or friction ring 9. The expansion ring is split, such as is apparent both from fig. 1 and 2, and the ends at the ope¬ ning of the expansion ring are tapered, with a radially outward convergence (see fig. 2). In the holder there is mounted an axial stopper pin 10 which enters the opening of the split ring 9. For interlocking the grinding pin 1 and the holder 4 there is in the grinding pin fitted a locking pin 11 which coope- rates with the bayonet groove 5 in the holder. On the holder there is an O-ring 12 mounted in a circumfe¬ rential groove. Likewise there is an O-ring 13 mounted in a circumferential groove in the grinding pin 1. Fig. 3 and 4 show a modified embodiment of the holder. The holder shown in fig. 3 and 4 is assembled from two compo¬ nents 15 and 16. The holder is provided with a bayonet groove 17 which corresponds to the bayonet groove 5 in the embodiment according to fig. 1 and 2. Between the two σom- ponents 15 and 16 there is room for a split ring 18 which corresponds to the split ring 9 of fig. 1 and 2. Also in the present case there is an stopper pin 19 corresponding to the stopper pin 10 of fig. 1 and 2. In the holder there is machined a groove 20 for an O-ring (not shown). A pin 21 extends transversely through the bore in the holder. In fig. 5-8 there is shown a two-part grinding pin. The lower part 22 is shown in fig. 5 and 6 while the upper part 23 is shown in fig. 7 and 8. The lower part 22 has a coni- cal end 24. The upper part 23 has a hollow conical end 25. The lower part of the grinding pin shown in fig. 5 and 6 has a locking pin 26 intended for cooperation with the bayonet groove 17 in the holder of fig. 3 and 4. Further¬ more it has a circumferential groove 27 for an O-ring which is not shown. The upper part 23 of the grinding pin has at its other end a groove 28 intended for cooperation with the pin 21 in the holder of fig. 3 and 4. During assembly the upper part 23 is inserted into the holder 14 from above while the lower part 22 of the grinding pin is inserted from below. Of course, the holder of fig. 3 and 4 can also be used for a grinding pin as shown in fig. 1 and 2. In this case one just removes the pin 21. In fig. 9 a grinding pin, for example the grinding pin 1 as shown in fig. 1 and 2, is shown mounted in a holder, ready for grinding the seat in the needle housing. The holder is in fig. 9 shaped as a slim cylindrical body, shaped and di¬ mensioned to be guidingly received in the needle bore in the needle housing. At its protruding end, when placed in the needle bore, the cylinder 29 has an extension 30 for coupling to a driving mechanism. In fig. 10 and 11 there is shown a fixture for fixing a needle housing when using an apparatus for example of the type shown in fig. 1 and 2. The fixture includes a bottom plate 31, provided with a blind bore 32 for receiving the nozzle part 33 of a needle housing 34. Into the bottom plate 31 there is screwed a stand bolt 35 with a clamping nut 36 as well as a stand bolt 37 with a clamping nut 38. A crossbar 39 has a bore 40 such that the crossbar can be placed on the stand bolt 35. Furthermore the crossbar has an opening 41 directed sideways such that the crossbar can be swung into and out of engagement with the other stand bolt 37 such as it appears from fig. 10 and 11. The needle housing 34 is clamped against the bottom plate 31 with the nozzle part 33 of the needle housing, as men¬ tioned already, positioned in .the blind bore 32 with an O- ring 42 laid in therebetween. The crossbar 39 is swung into position with a ring seal 43 laid in betwen the top of the needle housing 34 and the crossbar, thus to seal off the tilted fuel supply bore 44 in the needle housing. The needle housing is clamped into position by means of the nuts 36, 38. A holder 4 with corresponding grinding pin 1 is placed in the needle bore 45, see fig. 10, and the needle 46 which is to be ground is then inserted into the needle bore, such that the needle tip, not shown, bears agains the hollow co¬ nical bore 3 in the grinding pin 1 (see fig. 1). In a not specifically shown way the needle 46 is then brought into rotation, for example by introducing the fix¬ ture into a grinding machine. Acted on by the rotating needle the holder 4 will seek to rotate, but the stopper pin 10 (see fig. 1 and 2) will then act on the split ring 9 such that the latter expands and bears against the wall of the needle bore 45. This will fix the holder in relation to the needle housing. It will also fix the grinding pin 1 in relation to the needle housing. The grinding pin 1 will be placed in the seat 47 in the ring-shaped room 48 of the needle housing in a centering way such that one attains a desired guidance. When the grinding is finished, pressurized air is applied through the bore 49 which leads in to the blind bore 32. The pressurized air will enter through the nozzle holes in the nozzle part and will "shoot out" the holder 4 and cor¬ responding grinding pin 1. One can easily catch these parts by hand and thus remove them. The crossbar 39 is loosened and swung away to the side, and then the needle housing 34 can be taken out. The advantage which ±s realized according to the invention is in particular that the needle housing itself is exploi¬ ted as a guide. The holder is locked against rotational movement as a stopper pin will act on the split ring or ex¬ pansion ring. The assembly which consists of the grinding pin and the holder can easily be removed from the needle housing again after the grinding is finished, by means of pressurized air as described before. The needle housing will provide an ideal guidance because the needle and the needle housing are closely adapted to each other in diame¬ ters. Thus great precision is achieved. The flexible expan¬ sion ring or friction ring will be able to tolerate a cer¬ tain variation in diameters. Advantageously disposable grinding pins of hardened steel are used.

Claims: Patent claims 1. Apparatus for use in grinding the needle tip and seat in the needle housing of a fuel valve, c h a r a c t e r i z e d by a grinding pin ( 1) with a first conical end (2) adapted for the seat and a second hollow conical end (3) adapted for the needle tip, and by a self-centering and self-locking holder (4) for the grinding pin, shaped and dimensioned to be guidingly inserted into and locked within the needle bore (45) of the valve hou¬ sing, the grinding pin and- holder having cooperating ele¬ ments (5) for locking with a view towards relative rota¬ tion. 2. Apparatus according to claim 1, c h a r a c t e r i z e d in that the grinding pin (1) is intended for single use. 3. Apparatus according to claim 1 or 2, c h a r a c t e r i z e d in.that the holder (4) is a ca¬ sing which in a circumferential groove (8) carries a split ring (9) having a diameter a little larger than the needle bore (45), with an axial stopper pin (10) in the holder en¬ tering the opening of the split ring. 4. Apparatus according to claim 3, c h a r a c t e r i z e d in that the ends at the opening of the split ring are tapered such that they converge in outward radial directions. 5. Apparatus according to claim 3 or 4, c h a r a c t e r i z e d in that the cooperating ele¬ ments comprise a locking pin (11) and a locking groove (5). 6. Apparatus according to any preceding claim, c h a r a c t e r i z e d in that the grinding pin is se- parated into an upper (22) and a lower (23) part. 7. Apparatus according to one of the preceding claims 3-6, c h a r a c t e r i z e d by an O-ring (12) mounted in a circumferential groove (20) in the holder. 8. Apparatus according to any preceding claim, c h a r a c t e r i z e d by an O-ring (13) mounted in a circumferential groove (27) in the grinding pin (27). 9. Fixture for fixing the needle housing (34) in the use of the apparatus according to any preceding claim, c h a r a c t e r i z e d by a bottom plate (31) with a blind bore (32) for receiving, by the intermediate of an O- ring (42), the valve part (33) of the needle housing, with a bore (49) for the supply of compressed air to the room within the blind bore under the .valve part, and with a crossbar (39) which can be mounted (36, 38) to the bottom plate (31) abutting the top of the needle housing, by the intermediate of a seal (43) which seals the fuel supply bore (44) in the needle housing (34).

Inventors: KALLEBERG JACOB, KALLEBERG, JACOB
Applicants: TECH NOR INTERNATIONAL A S, TECH-NOR INTERNATIONAL A/S
Application year: 1987
Main classification: B24B15
IPC codes: B24B15