EP1846656B1 - Electric separation in fuel injectors - Google Patents

Description

Technical area

In fuel injection systems for direct injection internal combustion engines fuel injectors are used which contain one or more electrically controllable valves. Thus, for example, an electrically controllable solenoid or piezoelectric valve can be provided for controlling a needle valve and thus for controlling the course of the injection. Other valves can be used for example for a pressure boosting. However, the separate testing of the functionality of the individual valves and the components connected to or controlled by these valves often presents a challenge.

State of the art

Since the or the electrically controllable valves are typically housed inside an injector body, the preparation, testing and electrical contacting of these electrically controllable valves and the maintenance of the electrically controllable valves often causes considerable technical difficulties.

In many cases, there is an electrical contact at the top of the injector body which can be connected to a corresponding control system and power supply system located outside of the injector body. About this contact (which may be multiple plugs or multiple individual plugs) are usually all recorded in the interior of the injector electrically driven valves controlled. In the interior of the injector body, this electrical contact must be connected to corresponding contacts of the or the electrically controllable valves of the injection system. This connection is usually made by means of flexible electrical cables and a simple soldering process.

However, this method for electrical contacting of the electrically controllable valves is associated with various disadvantages. So the process is technically very complex, since usually the cables must be soldered by hand to the corresponding electrical contacts. This process step causes in practice a lot of effort and time. Furthermore, the connection between the electrically controllable valves and the electrical contact on the injector body is difficult to solve again. For disassembly or disassembly of the injector body typically soldered or welded joints must be separated again. Such a complex process has the effect that maintenance of the injectors or replacement of individual parts of the injector body is in many cases unprofitable.

In addition, in this method, the testing of the various functionalities of the fuel injectors sometimes poses considerable problems. In many cases, the fuel injector, when a malfunction occurs in the assembled state during testing, usually has to be laboriously disassembled again. After the repair or replacement of individual components (eg an electrically controllable valve) and reassembly, the functionality must then be tested again. This method is in many cases too time-consuming and thus unprofitable.

DE 10 2004 008 349 A1 refers to a fuel injection system comprising two common rail bodies for injecting fuel at two independently controlled pressures. The fuel injection system comprises at least one fuel injector having an injector body divided into a fuel pressure part having a fuel pressure assembly and an injection part having a directly controlled nozzle assembly. The fuel pressure assembly is coupled to a first electrical actuator, the directly controlled nozzle assembly to a second electrical actuator. The second electrical actuator has a pair of electrical terminals with a mating electrical extension formed within the injector body. This opens into connections for insulated conductors outside of the fuel pressure part.

DE 10 2004 008 349 A1 describes a Krafstoffinjektor according to the preamble of claim 1.

Presentation of the invention

According to the invention, therefore, a fuel injector for injecting fuel into a combustion chamber of an internal combustion engine and a method for producing such a fuel injector are proposed, which avoid the described disadvantages of the prior art. A basic idea of the present invention is that an injector body of the fuel injector has at least two separate functional units which are independently operable (independently of each other, for example, at least with respect to at least one functionality) and can be tested independently of one another. According to the invention, a first functional unit has a control module for controlling a pressure transmission of a fuel pressure and a second functional unit has a nozzle module for actuating an injection process by means of an injection valve member. The functional units are reversibly connected to one another via at least one frictional connection element (for example a union nut) and at least one positioning pin. Instead of one or more positioning pins according to the invention also equivalent means can be used, for example, projections in the housing of a functional unit, which engage in corresponding grooves in the other functional unit and so prevent rotation of the functional units relative to each other and facilitate the positioning of the functional units relative to each other.

The two functional units each have at least one electrically controllable valve (for example a solenoid valve). Furthermore, the fuel injector has at least one electrical injector body contact accessible from an outer side of the injector body, the second electrically controllable valve having at least one valve contact, and wherein the at least one electrical valve contact and the at least one electrical injector body contact at least partially under at least one of its own weight force in Substantially dimensionally stable electrical solid conductors are connected. This electrical connection between valve contacts and injector body contact also includes at least one electrical plug contact, in which the at least one electrical solid conductor is inserted.

The fuel injector according to the invention allows a much simplified compared to the prior art manufacturing process. Thus, in particular, a first functional unit can firstly be produced and tested, for example with respect to the functionality of an electrically controllable valve. Subsequently or in parallel thereto, a second functional unit is manufactured and tested, again for example with regard to the functionality of an electrically controllable valve. Finally, the functional units are reversibly connected to each other by means of the non-positive connecting element, wherein an electrical connection between the at least one injector body contact the at least one valve contact is made, for example by inserting into an electrical plug contact.

The separate testing of the individual functional units considerably increases the process stability during the production of the fuel injectors and makes it possible to detect faults (for example electrical faults of the individual valves) at an early stage and to correct them if necessary. The functional units can thus also be produced separately and independently of each other. Even a simple disassembly and repair for maintenance is possible. This reduces overall manufacturing and maintenance costs and increases the reliability of the fuel injectors.

drawing

In the following the invention will be described in more detail with reference to the embodiments illustrated in the figures. The same reference numerals designate the same or mutually corresponding in their function components.

Figur 1

eine Schnittdarstellung eines eine erste Funktionseinheit (Steuereinheit) und eine zweite Steuereinheit (Düseneinheit) aufweisenden Kraftstoffinjektors;

Figur 2A

eine perspektivische Darstellung der Trennung von Steuereinheit und Düseneinheit;

Figur 2B

eine perspektivische Darstellung der Steuereinheit;

Figur 2C

eine perspektivische Teildarstellung der Düseneinheit;

Figur 3A

eine perspektivische Darstellung einer mittels Positionierstiften relativ zu einer Düseneinheit positionierten Steuereinheit;

Figur 3B

eine perspektivische Darstellung der Funktionseinheiten gemäß Figur 3A nach Zusammenstecken von Steuereinheit und Düseneinheit;

Figur 3C

eine perspektivische Darstellung einer kraftschlüssigen Verbindung der beiden Funktionseinheiten gemäß Figur 3B mittels einer Überwurfmutter; und

Figur 4

einen Ablaufplan eines erfindungsgemäßen Verfahrens.

In detail shows:

FIG. 1

a sectional view of a first functional unit (control unit) and a second control unit (nozzle unit) having fuel injector;

FIG. 2A

a perspective view of the separation of the control unit and nozzle unit;

FIG. 2B

a perspective view of the control unit;

Figure 2C

a partial perspective view of the nozzle unit;

FIG. 3A

a perspective view of a positioned by means of positioning pins relative to a nozzle unit control unit;

FIG. 3B

a perspective view of the functional units according to FIG. 3A after mating of control unit and nozzle unit;

FIG. 3C

a perspective view of a non-positive connection of the two functional units according to FIG. 3B by means of a union nut; and

FIG. 4

a flowchart of a method according to the invention.

variants

In FIG. 1 an overall view of a preferred embodiment of an injector body 110 for a common rail injection system is shown. The injector body 110 can be dismantled at the butt joints 124, 126, 128 and 130 into substantially five functional modules 132, 134, 136, 138, 140: a control module 132, a sealing plate 134, a line connection module 136, a pressure booster module 138 and a nozzle module 140. The pressure booster module 138 essentially serves to translate a fuel pressure, which is provided by an external pressure source, for example via a high-pressure common space, to the fuel injector (for example 1000 bar) into a second pressure (for example 2200 bar). so that two working pressures are available for the injection process. The nozzle module 140 has an injection valve member 146 (in FIG FIG. 1 symbolically indicated only), for example a nozzle needle, which controls the actual injection process into the combustion chamber of an internal combustion engine (for example via injection openings).

The modules 132, 134, 136 and 140 are grouped in this embodiment into two functional units 148, 150: one comprising the control module 132 and the sealing plate 134 Control unit 148 and a nozzle unit 150 comprising the line connection module 136, the pressure booster module 138 and the nozzle module 140. These two functional units 148 and 150 are separated from each other by the second butt joint 126 and are reversibly connected by a cap nut 152. Furthermore, the functional units 148, 150 are still connected via the positioning pins 154 (in the sectional view according to FIG. FIG. 1 only one of the positioning pins 154 can be seen), which are respectively received in corresponding positioning bores 156 in the control module 132, in the sealing plate 134 and in the line connection module 136.

Furthermore, the injector body 110 has two solenoid valves 111, 112: a first solenoid valve 111 arranged in the control module 132 for controlling the pressure transmission in the pressure booster module 138, and a second solenoid valve 112 arranged in the nozzle module 140 for controlling the actual injection process via the injection valve member 146.

The separability of the two functional units 148, 150 along the second butt joint 126 causes the ("dry") control module 132 and the ("wet") portion of the injector body 110 located below the first butt 124 to be designed, manufactured and tested separately, to be assembled afterwards. In addition, due to this separability for maintenance purposes, for example, easily replace individual components of the injector body 110, which accommodates the "system repair idea" (SIS).

The solenoid valve 112 in the nozzle module 140 is electrically actuated via two electrical valve contacts 114. The injector body 110 has at its upper end an electrical injector body contact 116 accessible from above. The realization of a disassembly of the injector body 110 or a simple modular assembly consists in the illustrated modular design of the injector body 110 in such a way to electrically connect the valve contacts 114 to the injector body contact 116 that further ensures easy assembly and disassembly of the injector body.

To connect the two electrical valve contacts 114 to the injector body contact 116, two conductor channels 120 are provided in this embodiment, which extend through the modules 138, 136 and 134. The conductor channels 120 are formed by bores in the pressure booster module 138, in the line connection module 136 and in the sealing plate 134. When the injector body 110 is assembled, these bores are in each case flush with the butt joints 128 and 126, so that a single, continuous conductor channel 120 results.

The individual holes of the conductor channel 120 have in this embodiment in the individual modules 138, 136, 134 each have a straight course. A curved course of the holes can be realized with the inventive solution. However, the bores in the individual modules 138, 136, 134 each have a different inclination to an injector axis 142. While the conductor channel 120 in the pressure booster module 138 has an inclination of 1 ° to the injector axis 142, the inclination in this embodiment in the line connection module 136 is 2.2 °. These different angles of inclination relative to the injector axis 142 are due to the fact that the injector body 110 tapers downwards in its cross section, that is to say from the control module 132 to the nozzle module 140.

The connection between the two electrical valve contacts 114 of the solenoid valve 112 and the injector body 116 in this embodiment partially via two solid conductors 118. The solid conductors 118 extend through the two conductor channels 120 and connect the valve contacts 114 with electrical plug contacts 122, which in turn via an electrical Connection 144 (for example, two each at one end with an electrical plug contact 122 and at another end with the injector body contact 116 soldered cables) are connected to the injector body contact 116. The solid conductors 118 are fixed or detachably connected electrically to the valve contacts 114 of the solenoid valve 112.

The connection of the solid conductors 118 with the plug contacts 122 is reversible, so that this connection can be made during assembly of the injector body 110, so when mating control unit 148 and nozzle unit 150 by simply pressing in the solid conductor 118 into the plug contacts 122. On the other hand, during maintenance, the solid conductors 118 can be easily removed again from the plug contacts 122, and thus the injector body 110 can be broken down again into the two functional units 148, 150 without unsoldering of electrical connections.

The solid conductors 118 are stiff enough that they on the one hand do not change their shape substantially under their own weight and thus thread easily through the conductor channels 120 with their different inclinations to Injektorachse 142 and plug into the plug contacts 122. The solid conductors should have a certain plasticity, so that no mechanical stresses occur at the transition between sections of the conductor channels 120 with different angles of inclination. The term "solid conductor" does not necessarily restrict the selection of materials to solid materials, but it is also possible, for example, to use waveguides (tubes) as solid conductors 118, provided they have sufficient mechanical rigidity.

In the in FIG. 1 illustrated embodiment, the solid conductors 118 CuSn6 with a Brinell hardness between 80 and 90 HB as a material, which is otherwise used for example as welding filler. Alternatively, however, it is also possible, for example, to use CuA18, CuA18Ni2, CuA18Ni6, CuA19Fe, CuMn13A17, CuSi3, CuSn, copper or nickel silver. These materials meet the above requirements for hardness and plasticity and are also easily connected by welding with the valve contacts 114. The hardness of the materials should be between 50 and 100 HB, preferably between 60 and 95 HB and particularly advantageously between 75 and 90 HB.

In the FIGS. 2A to 2C the composition of the fuel injector from the two individual functional units 148 and 150 is shown in perspective. In particular in FIG. 2A It can be seen how the control unit 148 and the nozzle unit 150 along the butt joint 126 can be separated from each other by the union nut 152 is released. It is in FIG. 2A also to recognize that the nozzle unit 150 has a fuel supply nozzle 210, via which the nozzle unit 150 can be supplied with fuel. This fuel supply nozzle 210 may for example be connected to a high-pressure accumulator (common rail). In particular, in this embodiment, the sealing plate 134 (see FIG. 1 ), which is arranged in the control unit 148, be designed such that it prevents penetration of fuel via the butt joint 126 from the nozzle unit 150 into the control unit 148. Thus, as described above, the butt joint 126 separates the "wet" nozzle unit 150 from the "dry" control unit 148. This also helps to make both functional units 148, 150 separately manufacturable and separately testable.

In FIG. 2B a control unit is shown in perspective view. It can be seen here that the injector body contact 116, which is arranged on the upper side of the control unit 148, has four individual connection bolts 212 in this exemplary embodiment. In each case one of the two solenoid valves 111, 112 can be actuated via in each case two of these connection bolts 212.

Furthermore, in FIG. 2B to recognize that in this embodiment, two positioning pins 154 are embedded in the control unit 148. These positioning pins 154 may, for example, be permanently or detachably embedded in corresponding positioning bores 156 of the control unit 148 (see FIG FIG. 1 ). As already described above, according to the invention, instead of positioning pins 154, other devices can also be used which simplify positioning of the functional units 148, 150 relative to one another and prevent the functional units 148, 150 from rotating relative to one another. In particular, projections and corresponding grooves are to be mentioned here.

In Figure 2C is shown in perspective partial view, the upper end of the nozzle unit 150. It can be seen that the upper ends of the solid conductors 118 protrude from the line connection module 136. The solid conductors 118 are encased for insulation against the injector body 110 with shrink tubing 214, but the upper ends are stripped to make contact. As related to FIG. 1 can be seen when mating the functional units 148, 150, the upper ends of the solid conductors 118 pushed through conductor channels 120 in the sealing plate 134 and inserted into the plug contacts 122. In addition, at the top of the ends of the solid conductors 118 in this exemplary embodiment, O-rings 216 are plugged, which are intended to additionally prevent the penetration of fuel from the nozzle unit 150 along the solid conductors 118 into the control unit 148.

Furthermore, in Figure 2C also to recognize the mouths of the positioning holes 156, in which the positioning pins 154 of the control unit 148 when assembling the two functional units 148, 150 are inserted to ensure an exact positioning of the control unit 148 relative to the nozzle unit 150 and so a "blind" plugging the solid conductors 118 in the plug contacts 122 to allow.

In the FIGS. 3A to 3C an assembly of the functional units 148, 150 is shown in perspective. First, as in FIG. 3A shown, the positioning pins 154, which, as in FIG. 2B can be seen, in this embodiment, fixedly connected to the control unit 148, inserted into the positioning holes 156 of the nozzle unit 150. As a result, the control unit 148 is positioned relative to the nozzle unit 150, so that both functional units 148, 150 can no longer rotate relative to one another. Thus, the plug contacts 122 relative to the upper ends of the solid conductors 118 already have the correct position. Thus, a "blind" joining of the two functional units 148, 150 by movement of the control unit 148 in the joining direction 310 is possible, the upper ends of the solid conductors 118 are inserted into the plug contacts 122 and thus an electrical connection between the valve contacts 114 of the second solenoid valve 112 and the injector body contact 116 is made (see FIG. 1 ). The state of the two functional units 148, 150 after mating of the two functional units 148, 150 is in FIG. 2B shown in perspective. The union nut 152 is in the FIGS. 3A and 3B omitted for clarity. After the mating of the two functional units 148, 150, both functional units 148, 150 are connected to one another in a force-locking manner by screwing down the union nut 152. For maintenance purposes, this connection can be easily released again by the union nut 152, so that, for example, both functional units 148, 150 can be checked and maintained separately from each other.

In FIG. 4 is a schematic flow diagram of a method according to the invention for producing a fuel injector shown schematically. The illustrated process steps do not necessarily have to be performed in the order shown, and there may also be other, in FIG. 4 not shown process steps are performed.

In a first method step 410, a first functional unit 148 of a fuel injector is produced, which has at least one injector body contact 116 and at least one first electrically controllable valve 111. In method step 412, a first functionality of the first functional unit 148, in particular an electrical function of the first electrically controllable valve 111, is checked.

Independently of the method steps 410 and 412, a second functional unit 150 is produced in method step 414, which has at least one second electrically controllable valve 112 with at least one electrical valve contact 114. In method step 416, a second functionality of this second functional unit 150, in particular an electrical function of the second electrically controllable valve 112, is checked. In the (optional) method step 418, both functional units 148, 150 are then positioned relative to one another by at least one positioning pin 154. Subsequently, in method step 420, the first functional unit 148 and the second functional unit 150 are reversibly connected to each other at a butt joint 126 by means of at least one non-positive connecting element 152, wherein an electrical connection between the at least one injector body contact 116 and the at least one valve contact 114 is established. <U> REFERENCE LIST </ u> 110 injector 410 Production of the first functional unit 111 Solenoid valve in the control module 412 Test first functional unit 112 Solenoid valve in the nozzle module 414 Production of the second functional unit 114 valve Contact 416 Test second functional unit 116 injector body 418 Positioning of the functional units 118 solid Wire 420 Connection of the functional units 120 conductor channel 122 plug contacts 124 first butt joint 126 second butt joint 128 third butt joint 130 fourth butt joint 132 control module 134 sealing plate 136 Line connection module 138 Pressure booster module 140 nozzle module 142 the injector 144 electrical connection 146 Injection valve member 148 control unit 150 nozzle unit 152 Nut 154 positioning 156 positioning holes 210 Fuel supply nozzle 212 connecting bolt 214 shrinkable tubing 216 O-rings 310 joining direction

Claims (6)

1. Fuel injector for injecting fuel into a combustion chamber of an internal combustion engine,

   - wherein the fuel injector has an injector body (110),

   - wherein the injector body (110) has a first functional unit (148) comprising a control module (132) with at least one first electrically driveable valve (111) for controlling pressure intensification in a pressure intensification module (138),

   - wherein the injector body (110) has at least one second functional unit (150) which is different from the first functional unit (148) and has at least one second electrically driveable valve (112), comprising the pressure intensifier module (138) and a nozzle module (140),

   - wherein the first functional unit (148) and the second functional unit (148) are reversibly connected by at least one non-positive connecting element (152) and at least one positioning pin (154) at a butt joint (126),

   characterized in that the first functional unit (148) has at least one electrical injector body contact (116) which is accessible from an outer side of the injector body (110), wherein the second electrically driveable valve (112) has at least one valve contact (114), and wherein the at least one electrical valve contact (114) and the at least one electrical injector body contact (116) are connected at least partially by means of at least one electrical solid conductor (118) which is substantially dimensionally stable under its own weight, wherein the injector body contact (116) is accessible from above.
2. Fuel injector according to the preceding claim, characterized in that the non-positive connecting element (152) has at least one union nut (152).
3. Fuel injector according to the preceding claim, characterized by at least one electrical plug contact (122) for insertion of the at least one electrical solid conductor (118) for establishing an electrical connection between the injector body contact (116) and the at least one valve contact (114).
4. Fuel injector according to one of the preceding claims, characterized in that the first electrically driveable valve (111) and/or the second electrically driveable valve (112) has at least one solenoid valve .(111, 112).
5. Method for producing a fuel injector according to one of the preceding claims, comprising the following steps:

   a) a first functional unit (148) of the fuel injector is produced, wherein the first functional unit (148) has at least one injector body contact (116) and at least one control module (132) with at least one first electrically driveable valve (111) for controlling pressure intensification;

   b) a first functionality of the first functional unit (148), in particular an electrical function of the first electrically driveable valve (111), is checked;

   c) a second functional unit (150) is produced, wherein the second functional unit (150) has at least one pressure intensifier module (138) and a nozzle module (140) with a second electrically driveable valve (112) and at least one electrical valve contact (114);

   d) a second functionality of the second functional unit (150), in particular an electrical function of the second electrically driveable valve (112), is checked;

   e) the first functional unit (148) and the second functional unit (150) are reversibly connected to one another at a butt joint (126) by means of at least one non-positive connecting element (152), wherein an electrical connection is established between the at least one injector body contact (116) and the at least one valve contact (114),

   characterized in that, in method step e), at least one electrical solid conductor (118), which is substantially dimensionally stable under its inherent weight, is inserted into at least one electrical plug contact (122), and the injector body contact (116) is accessible from above.
6. Method according to the preceding claim, characterized by the following additional steps:

   f) the first functional unit (148) and the second functional unit (150) are positioned relative to one another by at least one positioning pin (154).

Images