GB2293785A

GB2293785A - Injection valve

Info

Publication number: GB2293785A
Application number: GB9519211A
Authority: GB
Inventors: Karl Hofmann
Original assignee: Robert Bosch GmbH
Current assignee: Robert Bosch GmbH
Priority date: 1994-10-07
Filing date: 1995-09-20
Publication date: 1996-04-10
Anticipated expiration: 2015-09-20
Also published as: ITMI952000A1; IT1277676B1; GB9519211D0; DE4435850C2; GB2293785B; JPH08121629A; DE4435850A1; ITMI952000A0

Description

2293785 Method of Inserting a connection stIM2 into a holasiucr

Prior art

The invention in based on a method of Inserting connection stubs into a housing, preferably of Inserting leakage-oil connection stubs Into the housing of an injection valve for internal cowbustion engines, In accordance with the generic type of Patent Claim 1.

In the case of a fuel Injection nozzle for internal combustion engines which 1 a known f rom DE 29 43 745 C2, the connection stub for the leakage-oil connection Is inserted by being pressed In, in which case, f or reliable fastening of the connection stub in the receiving bore of.the housing, knurling in provided on the circumferential surface thereof. However, analogously to the methods mentioned an alternatives In the description of the abovementioned document (pressing

In, caulking), this method of inserting the connection stub has, In practice, the disadvantage that, In order to achieve occur scaling between the wall of the receiving bore and the connection stub, a scaling c=Wowiti= (adhesive) =at additionally be applied to the connection seam, this considerably Increasing the manufacturing Outlay.

In addition, the applied sealing c=Wonitions of ten do not fulf il the requirements an regards their durability with respect to high temperature fluctuations and high m"i=,= te:Weratures, and this may result in the leakage of fuel.

Advantages of the invention In contrast, the method according to the inven tion of inserting connection stubs has the advantage that a reduction in assembly outlay can be achieved by virtue of the widening of the connection stub against the wall of the receiving bore in the housing. In addition, the connection-stub circumferential wall bearing uniformly is against the wall of the receiving bore reliably provides durable sealing, with the result that an additional application of a sealant can be dispensed with, which likewise simplifies the manufacturing process.

In this arrangement, it is possible to affect the widening of the inserted connection stub by mechanical means, as in the exemplary embodiment described, or else also by hydraulic or thermal devices.

in the case of the exemplary embodiments described, the widening of the connection stub in the receiving bore advantageously takes place by the full insertion of a mandrel with a head, of which the crosssection is greater than at least part of the throughpassage bore of the connection stub in the region of -overlap. with- the receiving bore, as a result of which said part of the through-passage bore is widened and, co nsequently, the connection stub in pressed against the wall of the receiving bore. This operation for inserting the mandrel into the connection stub can take place by the mandrel head being drawn in axially, in the direction away from the housing, counter to a counter- retainer which fixes the conjaection stub axially; however, it in also possible to press the mandrel in the direction towards the housing, it being possible, in this case, to dispense with an additional counter- retainer since the connection stub is advantageously supported axially on a stop fixed to the housing. in this arrangement, said stop may be f ormed by an annular shoulder on the circumf erence of the connection stub or by a bore shoulder of the receiving bore.

A further advantage is achieved by the conical cross-sectional transitions on the head of the mandrel and the through-passage bore of the connection stub, which transitions avoid tilting of the tool (mandrel) during the deformation displacement and possible notching effects within the connection stub. If the connection stub is widened by the insertion of the mandrel in the direction of the valve housing, it is, in addition, advantageous also for the cross-sectional transition between head and shaf t of the mandrel to be configured such that it is tapered conically and uniformly (double cone), in order thus to avoid tilting of the mandrel when it in drawn out of the connection stub. In addition, this may also be assisted by a bevelling of the transition between the connection-stub end side projecting into the housing and the through-passage bore of said connection stub.

The method according to the invention in intended to be used preferably for the insertion of leakage-oil connection stubs into the housing of an injection valve, but other applications in which a connection stub in to be arranged in a sealing Toanner on a housing are also possible. Further advantages and advantageous configura- is tions of the subject matter of the invention can be gathered from the description, the drawing and the patent claims.

Drawing Two exemplary embodinents of the method according to the Invention of inserting connection stubs into a housing are represented In the drawing and are explained in more detail In.the following description.

Figure 1 shown a partial section through a housing part of an Injection valve with a connection stub inserted therein, Figure 2 ohm a first exemplary embodiment of the method, In which the mandrel In drawn, from the bottom, into the connection stub inserted Into the housing, and Figure 3 shown a second exemplary embodiment of the method analogously to the representation of Figure 2, In which the mandrel In inserted into the connection stub from the top.

Description of the exemplary embodiments

A receiving bore 3, which opens into a spring chamber 5, is provided in the housing part 1 which in represented partly in section in Figure 1, forms a nozzle retainer and belongs to an injection valve (not otherwise shown In any more detail). Said spring chamber 5 receives a restoring spring (not shown) of the injection valve and, during the operation of the injection valve, is f Illed, via the shaf t of the valve member, with leaked fuel which flown off via the bore 3 into a return line.

Said return line (likewise not shown) in connected to the bore 3 by means of a connection stub 7 which forms a leakage-oil connection stub.

For this purpose, the connection stub 7 is inserted, with part of its circumferential surface, Into the receiving bore 3 in a scaling manner and in fastened there such that the return line can be plugged onto the connection stub 7, and drawn of f theref rom, without damaging thescaling connection thereof to the wall of the receiving bore 3.

For this purpose, the connection stub 7in inserted the receiving bore 3 of the housing 1 by means of a method according to the Invention and In fastened in said receiving bore 3 via a cross-sectional widening of the connection stub 7, of which two exemplary embodiments are explained with reference to Figures 2 and 3.

The connection, stub 7 used here is of the same design in both exemplary embodAments and, at Its end directed away from the housing 1, exhibits a fastening cone 9 onto which tLe return line in plugged and fastened. Furthermore, provision in made, on Its circumferential surface, for an annular shoulder 11 which in 30 formed by a cross-sectional reduction In the connection stub 7 in the direction away from the fastening cone 9 and by way of whose position the penetration depth of the connection stub 7 Into the receiving bore 3 in established, the cross-sectionally reduced end 13 of the 35 connection stub 7 penetrating fully into the receiving bore 3. in addition, the connection stub 7 exhibits a through-passage bore 15, the diameter of which decreases conically, in the region of the cross -sec tionally reduced end 13, in the direction of the end side 19 directed away from, the f astening conch 9.

In the case of the first exemplary embodiment, shown in Figure 2, of the zaathod according to the Invention, the connection stub 7 In first of all attached, with Its through-passage bore 15, onto a mandrel 17 such that It comes to bear, by sachans of Its end side 19 directed away fr= the fastening cone 9, against a head 21 which in provided at one and of the mandrel 17 and of which the cross-section widens conically fr= the diazactor of the mandrel shaft 23 to the dimension of the through-passage bore 15 in the non-reduced region. in this arrangement, the mandrel shaft 23, which in of a smaller diameter than the through-passage bore 15, projects out of the connection stub 7 to such an extent that a drawing tool can be fitted on it.

In a next step, the connection stub 7, with Inserted mandrel 17, In inserted into the receiving bore 3 In the housing 1, a small gap 25 remaining between the circumferential surface of the connection stub 7 in the region of the and 13 and the wall of the receiving bore 3.

A counter-retainer 27 in then attached onto that end of the connection stub 7 which projects out of the housing 1, It being possible for said counter- retainer 27 to bear both directly agaizat the and wide and against the conical surface of the fastening cone 9.

The actual fastening operation then takes place in that the mandrel 17 In drawn by its head 21 through the through-passage bore 15, the connection stub 7, In this arrangement, being retained axially by the counterretainer 27 which forms an abutment. An the mandrel head 21 runs through the region of the through-passage bore 15 of reduced diameter, the cross-section of the through- passage bore 15 widens to the dimension of the mandrel head 21, as a result of which the cross-section of the connection stub 7 in the region 13 In Increased such that, after running through the gap 25, the circuzateran tial surf ace of maid connection stub 7 in braced in a sealing manner against the wall of the receiving bore 3.

In this arrangement, depending on the tensile- strength requirements, the degree of this bracing can be adjusted via the difference in size between the mandrel head 21 and the diameter of the reduced through-passage bore IS.

in a final operation, the mandrel in then fully drawn through the throughpassage bore IS, the diameter of said through-pas sage bore IS outside the region 13 advantageously being slightly greater or equal to the largest croon-section of the mandrel head 21. Alterna- tively, a through-passage opening 29 for the mandrel 17 in the counter - retainer 27 may be of the same dimension as the mandrel shaft 23 or the mandrel head 21, with the result that, after the mandrel 17 has been fully drawn through the through-pairsage bore IS, the counter- retainer -27 can be removed along with it.

In the case of a second exemplary embodiment, represented in Figure 3, of the method according to the invention, the connection stub 7, designed analogously to the first exemplary embodiment, in, in a first method step, inserted into the receiving bore 3 in the housing 1 by means of its end 13 directed away from the fastening cone 9, the gap 2S likewise being maintained. In this arrangement, the plug-in depth of the connection stub is, here,-likewise determined via the Annular shoulder 11 or, an is represented, via a bore shoulder 31 of the receiving bore 3, against which the end surface 19 of the connection stub 7 comes to bear.

In a further operation, a mandrel 317 is plugged into the through-passage bore 15 from the upper end side, exhibiting the fastening cone 9, of the connection stub 7. At its lower end, said mandrel 317 exhibits a head 321, of which the cross-section increases conically, in the direction of the shaft 323 from the end side directed away from the shaft 323, to the dimension of the non- reduced diameter of the through-passage bore IS, the shaft diameter preferably being configured to be smaller than the diameter of the through-passage bore 15.

In this arrangement, the mandrel 317, when plugged in, first of all comes into abutment, with its head 321, against the beginning of the cross-sectional reduction in the through-passage bore 15.

In a further process step, the mandrel 317 is first, by means of a tool (not shown in any more detail), acting at that shaft and of the mandrel which projects out of the connection stub 7, through the through-passage bore 15 to the full extent by means of its head 321, as a result of which, as is described f or Figure 2, the cross-section of the connection stub 7 in the region 13 widens such that a sealing radial press-fit connection results between the wall of the receiving bore 3 and the circumferential wall of the connection stub 7.

In this arrangement, the bore shoulder 31 of the receiving bore 3 acts an an axial abutment against which is the connection stub 7 in supported. With the correspondingly large design, it in, alternatively, also possible to use the annular shoulder 11 as an abutment, this reducing the manufacturing outlay even further.

in a final operation, the mandrel 317 in then drawn out of the throughpassage bore again, it being advantageous, in this arrangement, for the largest head cross-section of the mandrel 317 to be configured to be slightly smaller than the diameter of the through-passage bore.

it is thus possible, using the method according to the invention of inserting connection stubs, to produce, in a simple maziner, a sealing and tensionresistant connection between stub and housing, said method, in particular, being advantageously suited for use for the insertion of leakage-oil connection stubs into the housing of injection valves for internal combustion engines since, in this case, there are particularly stringent requirements an far an the durability and leaktightness are concerned.

- a -

Claims

Patent claims

1. Method of inserting a connection stub (7) into a housing (1), characterized in that, after the insertion into a receiving bore (3) in the housing (1), the connec tion stub (7) Is braced, by =cans of a radial widening of its cross-sectional surface area in the region of the receiving bore (3), in a scaling manner against the wall of the receiving bore (3) by =cans of Its circumferential surface.

2. Method according to Claim 1, characterized by the following method steps:

- attachment of the connection stub (7) onto a mandrel (17) which exhibits a head part (21) of a greater diameter than at least part of a through-passage bore (15) of the connection stub (7), In the region of overlap with the housing (1), - Insertion into the receiving bore (3) of the housing (1) of that end of the connection stub (7) which In directed towards the head (21) of the mandrel (17), a small gap (25) being provided between the connection stub (7) and the wall of the receiving bore (3), attachment of a counter-retainer (27) onto that end of the -connection stub (7) which projects out of the receiving bore (3), - drawing cif the mandrel (17) through the through-passage bore (15) of the connection stub (7), said through passage bore being widened to the dimension of the head (21) of the mandrel (17), this effecting, in the region of overlap with the housing (1), a radial widening of the external diameter of the connection stub (7) to the size of the diameter of the receiving bore (3) in the housing (l) ' - rem val of the mandrel (17) and the counterretainer (27).

3. Method according to Claim 1, characterized by the following method steps:

- insertion of the connection stub (7) into the receiving bore (3) in the housing (1), the penetration depth of the connection stub (7) being established by a stop which for= an axial abutment, - plugging of a mandrel (317) into a through-passage bore (15) in the connection stub (7), the diameter of which through-passage bore in the region of overlap of the connection stub (7) with the housing (1) being smaller than a head (321), arranged at the lower end directed towards the housing (1), of the nuandial (317) at its largest point, - guidance of the head (321) of the mandrel (317) through the through-passage bore (15) of the connection stub (7), preferably until it emerges at the and side (19), arranged in the housing (1), of the connection stub (7), the diameter of the through-passage bore (15) In the is region of overlap with the housing (1) widening to the largest dimension of the head (321) of the mandrel (317), and the external diameter of the connection stub (7) widening to the size of the diameter of the receiving bore (3) In the housing (1).

4. Connection stub f or implementing the method according to Claims 2 and 3, characterized In that the connection stub (7) has a through-passage bore (15) which, in the region of the penetration depth of the connection stub (7) inserted Into the receiving bore (3), has a conical crosssectional progression which decreases in the insertion direction towards the housing Interior.

5. Connection stub according to Claim 4, characterized In that, on Its circumferential surf ace, the connection stub (7) exhibits an -nnular shoulder (11), by way of whose position the plug-in depth of the connection stub (7) Into the receiving bore (3) in established.

6. Device for fitting a connection stub according to Claim 4, characterized In that the head (21, 321) of the mandrel (17, 317) used Increases conically, counter to the direction of insertion into the connection stub (7), from a small cross-section to a large cross-section, the large cross-section being, at most, equal to the diameter of the through-passage bore (15) of the connection stub (7) outside the region of overlap with the receiving bore - 10 (3) of the housing (1).

7. - Connection stub according to one of the preceding Claims 1 to 6 for the Insertion and fastening of leakage-oil connection stubs Into the housing of an Injection valve for internal combustion engines.

8. Connection stub according to one of Claims 5 to 7, characterized In that the annular shoulder (11) forms the axial abutment of the connection stub (7) during the widening operation.

9. Device for f itting a connection stub according to Claim 8, characterized in that the receiving bore (3) exhibits a bore shoulder (31) against which the inserted connection stub (7) comes to bear with its and side (19), and which thereby forms the axial abutment of the connection stub (7) during the widening operation.

10. A method of inserting a connection stub substantially as herein described with reference to Figures 1 and 2, or Figures 1 and 3 of the accompanying drawing.

A connection stub substantially as herein described with reference t6 the accompanying drawing,.

12. A device for a connection stub substantially as herei:

described with reference to the accompanying drawing.