Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
  • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
  • F02M61/168—Assembling; Disassembling; Manufacturing; Adjusting
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M61/00—Fuel-injectors not provided for in groups F02M39/00 - F02M57/00 or F02M67/00
  • F02M61/16—Details not provided for in, or of interest apart from, the apparatus of groups F02M61/02 - F02M61/14
  • F02M61/18—Injection nozzles, e.g. having valve seats; Details of valve member seated ends, not otherwise provided for
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M2200/00—Details of fuel-injection apparatus, not otherwise provided for
  • F02M2200/80—Fuel injection apparatus manufacture, repair or assembly
  • F02M2200/8015—Provisions for assembly of fuel injection apparatus in a certain orientation, e.g. markings, notches or specially shaped sleeves other than a clip

Definitions

• the invention relates to a method for assembling a fuel injector, such as is used, for example, to introduce fuel under high pressure into a combustion chamber of an internal combustion engine.
• the invention relates to an assembly tool as is used in the method according to the invention.
• Fuel injectors such as those used to inject fuel under high pressure, consist of several components, usually a holder and a nozzle.
• the nozzle contains the injection openings through which the fuel is introduced into the combustion chamber.
• the nozzle is manufactured as a separate component and screwed to the holding body with a clamping nut. Since fuel is present within the holding body and the nozzle under a pressure of up to 2700 bar (270 MPa), the sealing surface between the nozzle and the holding body must be securely sealed so that no fuel escapes when the fuel injector is in operation.
• the nozzle is braced against the holding body by means of a nozzle clamping nut, so that the nozzle body is pressed against the holding body with great force, which results in the necessary tightness.
• the nozzle clamping nut surrounds the nozzle body and rests on a shoulder on the outside of the nozzle body.
• one or more dowel pins are required provided, which partly protrude into the holding body and partly into the nozzle and thus ensure exact positioning during assembly.
• a torque is exerted on the nozzle when the holding body is fixed, so that the clamping pins, which are intended to hold the nozzle in position relative to the holding body, are heavily mechanically loaded. This can lead to overstressing of the dowel pins or the nozzle body and ultimately to fuel failure, especially if the fuel injector is operated for a long time! injector.
• the assembly method according to the invention for a fuel injector has the advantage that a high-pressure-tight assembly of the fuel! njektors is made possible without overloading the roll pins or other devices during assembly, which avoids breakage or failure of the injector during operation.
• the assembly procedure is based on a fuel! performed njektor comprising a holding body and a nozzle body, wherein the outside of the nozzle body is rotationally symmetrical and an im Has a larger diameter nozzle collar and a smaller diameter shank. A clamping shoulder is formed at the transition from the shank to the nozzle collar.
• the fuel injector includes a nozzle clamping nut, which is screwed with an internal thread into an external thread on the holding body, the nozzle clamping nut being supported on the clamping shoulder, so that the nozzle body is clamped at least indirectly against the holding body.
• the assembly tool used in the method has a receptacle for the shank of the nozzle body and is pushed over the shank of the nozzle body until the assembly tool rests against a clamping surface of the nozzle body.
• a prestressing force is then exerted on the nozzle body with the assembly tool, which force presses the nozzle body at least indirectly against the holding body, with the assembly tool clamping the shank of the nozzle body laterally.
• the nozzle clamping nut is then screwed on until a defined contact pressure is reached between the nozzle body and the holding body.
• the clamping tool is used to exert an axial force on the nozzle body in the direction of the holding body, so that the nozzle body is held in an assembly position, with the assembly tool also laterally clamping the shank of the nozzle body.
• the assembly tool can absorb a significantly greater torque on the nozzle body than would be the case with only axial contact pressure. If the nozzle clamping nut is now screwed on, it exerts a torque on the nozzle body in relation to the holding body due to the friction on the clamping shoulder, but the assembly tool holds the nozzle body in its position by laterally clamping the nozzle body in the area of the shaft until the nozzle clamping nut has been screwed in with a defined torque.
• the assembly tool is then removed and the nozzle body is braced against the holding body with the desired contact pressure without mechanical overloading of parts of the fuel! njektors, in particular the dowel pins between the holder body and the nozzle body comes.
• the clamp is advantageously designed in such a way that the torque that the assembly tool can absorb is sufficient to hold the nozzle body in the defined position, while the clamping nut is tightened to the defined torque in relation to the holding body without the nozzle body rotating in relation to the holding body. It is irrelevant whether the nozzle body rests directly on the holding body or only indirectly, ie with the interposition of further housing parts, such as a throttle plate or other body.
• the assembly tool rests on a clamping surface on the nozzle body, which is formed on a circumferential shoulder on the shank of the nozzle body.
• the axial force can be introduced without mechanically loading the area of the clamping shoulder.
• the section of the nozzle body with the larger diameter is also less deformed during assembly, which is particularly advantageous if the nozzle needle arranged in the nozzle body is guided in this section of the nozzle body and even a slight deformation of the nozzle body in this area can impair the nozzle needle guidance .
• the assembly tool is designed in such a way that it is elastically deformed inward by the prestressing force, as a result of which the mounting tool holder exerts a clamping force on the shank of the nozzle body.
• This can be achieved in particular in that the hollow-cylindrical receptacle of the assembly tool is curved concavely inwards on the inside.
• a longitudinal force on the assembly tool causes the receptacle to be deformed radially inwards, so that the assembly tool, which is designed with only little play relative to the shaft of the nozzle body, clamps the shaft with great force and thus enables a high torque to be transmitted .
• the outside of the assembly tool can also be concavely curved inwards, in addition to or instead of a concave curvature of the inside of the assembly tool, in order to achieve the necessary deformation of the assembly tool by the longitudinal force.
• a inserted hollow-cylindrical spacer wherein the clamping force between the assembly tool and the shaft is transmitted through the spacer.
• the intermediate piece is made from a material that is soft compared to the nozzle body or the assembly tool, for example a soft metal (e.g. copper) or a plastic, so that it rests on the nozzle shaft and the assembly tool over a large area and has a high clamping force between the assembly tool and the stem of the nozzle body.
• the intermediate piece can be conical on its inside and/or on its outside, so that it is already clamped between the assembly tool and the shank of the nozzle body by axially inserting the nozzle body into the assembly tool.
• the clamping tool is conically shaped on its inside, so that the contact pressure on the shaft of the nozzle body is additionally increased.
• the clamping tool according to the invention for use in the method according to the invention has a hollow-cylindrical receptacle for the shank of a nozzle body, the wall of the cylindrical receptacle being designed such that the inner wall of the receptacle deforms inward when a longitudinal force is applied to the clamping tool. This exerts a clamping force on the stem of the nozzle body, which serves to absorb or exert a torque on the nozzle body.
• the deformability of the clamping tool can be produced in an advantageous manner in that notches, grooves or grooves are formed on the outside, which preferably run in the longitudinal direction of the cylindrical receptacle.
• the hollow-cylindrical receptacle of the clamping tool from an inner cylinder and an outer cylinder that are firmly joined together, the inner cylinder being made of a material with a lower modulus of elasticity than the outer cylinder.
• the cylindrical receptacle is deformed inwards by a longitudinal force, so that the desired clamping force is created on the shank of the nozzle body.
• the drawing shows illustrations of the method according to the invention. It shows
• Figure 1 is a longitudinal section through a known fuel! injector with an assembly tool according to the invention
• FIG. 5 shows a longitudinal section through another device according to the invention
• FIG. 1 shows a fuel known from the prior art! njektor shown in longitudinal section, with only the essential parts are shown.
• FIG. 1 shows an assembly tool for carrying out the method according to the invention.
• the fuel! njektor 1 comprises a holding body 2 and a nozzle body 4, which are braced against one another by means of a clamping nut 7. This creates a liquid-tight connection between the two bodies, which seals off the fuel-carrying channels that lead from the holding body 2 into the nozzle body 4, even when the fuel pressure is high.
• the nozzle body 4 has at its combustion chamber side - in the figure 1 right - end of several injection openings 9, through which the fuel under high pressure during operation of the fuel! ejector is ejected.
• a longitudinally displaceable nozzle needle is arranged inside the nozzle body 4, which is not shown in FIG. 1 for the sake of clarity and is well known from the prior art.
• the nozzle body 5 is of essentially rotationally symmetrical design and is fixed in its position relative to the holding body 2 by dowel pins 12 .
• the nozzle body 4 has a nozzle collar 5 with a larger diameter, which is adjoined by a shaft 6 with a smaller diameter, which extends to the end of the nozzle body 4 on the combustion chamber side.
• a clamping shoulder 8 is formed on the nozzle body 4, on which the clamping nut 7 engages.
• a circumferential shoulder 14 is formed on the shank 6, on which a clamping surface 13 is formed, which is oriented in the same way as the clamping shoulder 8, but is formed significantly smaller in diameter.
• An internal thread 10 is formed in the clamping nut 7 and engages in an external thread 11 formed on the holding body 2 .
• the nozzle body 4 is clamped against the holding body 2 by screwing the clamping nut 7 , which acts on the clamping shoulder 8 . Since the force is introduced at the clamping shoulder 8, when the clamping nut 7 is screwed on, a torque is exerted on the nozzle body 4, which leads to a mechanical load on the clamping pins 12.
• the following method is used: When assembling the nozzle body 4 on the holding body 2, an assembly tool 16 is used, as shown in of Figure 1 is shown.
• the assembly tool 16 has a cylindrical receptacle 17 which receives the shank 6 of the nozzle body 4, but with only a small amount of play relative to the inner wall of the receptacle 17 remaining.
• the assembly tool 16 is pushed over the shank 6 until the assembly tool 16 comes to rest on the clamping surface 13 of the peripheral shoulder 14 .
• An axial prestressing force is now exerted on the nozzle body 4 via the assembly tool 16, which force presses the nozzle body 4 against the holding body 2 in the axial direction.
• the cylindrical receptacle 17 of the assembly tool 16 is curved concavely inwards and the cylindrical receptacle 17 is elastically compressed by the application of the axial prestressing force, the cylindrical receptacle 17 is slightly deformed inwards and thereby clamps the shank 6 of the nozzle body 4
• Assembly tool 16 absorbs and compensates for a torque acting on the nozzle body 4 both via the clamping of the shank 16 and via the friction on the clamping surface 13 .
• the nozzle clamping nut 7 is now screwed onto the external thread 11 until the desired prestressing force of the nozzle body 4 relative to the holding body 2 is reached. The assembly tool 16 is then removed.
• the assembly tool 16 can compensate for very high torques on the nozzle body 4 .
• the nozzle clamping nut 7 can therefore be screwed onto the holding body 2 with a high torque, so that a high axial contact pressure of the nozzle body 4 on the holding body 2 can be achieved without the position of the nozzle body 4 being displaced in relation to the holding body 2 during assembly and without risking mechanical overloading of the dowel pins 12 or the nozzle body 4, which would otherwise give way during further operation of the fuel injector due to the high mechanical and hydraulic loads and could lead to a failure of the fuel injector.
• FIG. 2 shows a further exemplary embodiment of the assembly tool 16 according to the invention in the same representation as FIG. 1, as it can be used in the method according to the invention.
• the cylindrical receptacle 17 of the assembly tool 16 is concavely curved inwards both on the inside and on the outside. This increases the deformation of the assembly tool 16 during the application of the axial preload force F a , such that an inward clamping force F 1 acts on the sides of the assembly tool 16 and deforms it inward.
• plastic deformation of the assembly tool during assembly of the fuel injector is excluded.
• FIG. 3 shows a further exemplary embodiment of an assembly tool 16 according to the invention, as can be used in the method according to the invention.
• a cylindrical spacer 19 is arranged between the cylindrical receptacle 17 of the Assembly tool 16 and the shaft 6, a cylindrical spacer 19 is arranged.
• the intermediate piece 19 is designed as a hollow cylinder and, due to its position between the assembly tool 16 and the shaft 6, transmits the clamping force between the assembly tool 6 and the nozzle body 4.
• the intermediate piece 19 is made of a relatively soft material, for example a soft metal such as copper or also made of a polymer. Due to its flexibility, the intermediate piece 19 transmits the clamping force over a large area of the shank 6.
• the intermediate piece 19 can also have a conical shape on its outside, as shown in FIG. Because of its conical shape, the intermediate piece 19 is clamped between the assembly tool 16 and the nozzle body 4 as soon as the assembly tool 16 is pushed over the shaft 6 .
• the inside of the assembly tool 16 ie the receptacle 17 , can also be designed conically in order to strengthen the clamping of the intermediate piece 19 when it is pushed over the shaft 6 .
• FIG. 5 shows another assembly tool in longitudinal section, as can be used in the method according to the invention.
• the cylindrical receptacle 17 of the assembly tool 16 is formed here by two concentrically arranged hollow cylinders, an inner cylinder 21 and an outer cylinder 22, which are firmly connected to one another.
• the two cylinders 21, 22 are made of materials with a different modulus of elasticity, with the inner cylinder 21 having a lower modulus of elasticity than the outer cylinder 22.
• the inward movement of the cylindrical section 17 is facilitated by the different deformation behavior and the clamping force F is thus increased. so that the stem 6 of the nozzle body 4 is securely clamped.
• the assembly tool 16 can also be provided with structures on its outside, such as grooves or grooves, which preferably run in the longitudinal direction of the assembly tool 16 .
• the structures reduce the strength on the outside and increase the deformability, which increases the clamping force F,.
• the assembly tool 16 acts on the clamping surface 13 of the circumferential shoulder 14 .
• the clamping tool 16 can also be attached to the tip of the nozzle body 4, ie at the end of the nozzle body 4 on the combustion chamber side in the area in which the
• Injection openings 9 are formed. If there is no circumferential shoulder 14 on the nozzle body 4, it is also possible for the assembly tool 16 to act directly on the clamping shoulder 8 and apply the necessary axial prestressing force there.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Manufacturing & Machinery (AREA)
• Fuel-Injection Apparatus (AREA)

Applications Claiming Priority (2)

Publications (1)

Family

ID=76971862

Family Applications (1)

Country Status (4)

Family Cites Families (3)

• 2020
  • 2020-07-30 DE DE102020209636.8A patent/DE102020209636A1/de active Pending
• 2021
  • 2021-07-07 CN CN202180067123.5A patent/CN116234979A/zh active Pending
  • 2021-07-07 EP EP21743108.9A patent/EP4189229A1/de active Pending
  • 2021-07-07 WO PCT/EP2021/068856 patent/WO2022022965A1/de active Application Filing

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