Abstract:
A jet needle has a front face turned away from an injection opening. An injector assembly has a chamber within the body adjoining the front face, a throttle module arranged in the chamber having a fluid supply chamber being hydraulically coupled to the fluid inlet, a control space hydraulically coupled to the fluid supply chamber via an inlet throttle, and a valve chamber hydraulically coupled to the control space via an outlet throttle for accommodating a valve that is designed to lead fluid into a fluid return line arranged in a control module. There are precisely two sealing edges designed between the throttle module and the injector body and/or the control module by which additional hydraulic couplings of the fluid supply chamber to the control space and the valve chamber are cut off. A third sealing edge is designed between the injector body and the control module.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a U.S. National Stage Application of International Application No. PCT/EP2010/050791 filed Jan. 25, 2010, which designates the United States of America, and claims priority to German Application No. 10 2009 007 213.6 filed Feb. 3, 2009, the contents of which are hereby incorporated by reference in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The invention relates to an injector assembly for an injection valve, having an injector body, having a nozzle needle which is arranged in a recess of the injector body in such a way that it prevents a fluid flow through at least one injection opening in a closed position and releases a fluid flow through the injection opening in an open position. Furthermore, the invention relates to an injection valve having an injector assembly and an actuator unit, the injector assembly and the actuator unit being coupled to one another. 
       BACKGROUND 
       [0003]    More and more stringent legal directives with regard to the permissible pollutant emissions of internal combustion engines which are arranged in motor vehicles make it necessary to perform diverse measures, by which the pollutant emissions are lowered. A starting point here is to lower the pollutant emissions which are produced by the internal combustion engine. The formation of soot is greatly dependent on the preparation of the air/fuel mixture in the respective cylinder of the internal combustion engine. 
         [0004]    Correspondingly satisfactory mixture preparation can be achieved if the fuel is metered in under very high pressure. In the case of diesel internal combustion engines, the fuel pressures are up to 2000 bar. High pressures of this type place high requirements both on the material of the injector assembly and on its construction. At the same time, great forces have to be able to be absorbed by the injector assembly. 
         [0005]    DE 102 20 931 C1 discloses an injector for injecting fuel into a combustion chamber of an internal combustion engine. The injector comprises an injector body, a nozzle needle and a control device, in order to control a pressure in a control space for actuating the nozzle needle. Furthermore, the injector comprises an inflow throttle and an outflow throttle which are hydraulically connected to the control space. The inflow throttle and the outflow throttle are arranged in a throttle module which is formed as a separate component and is sealed by means of cutting edges. 
       SUMMARY 
       [0006]    According to various embodiments, an injector assembly and an injection valve can be provided, which injector assembly or injection valves makes reliable and precise operation possible and is configured in a spacesaving manner. 
         [0007]    According to an embodiment, an injector assembly for an injection valve may have—an injector body with a central longitudinal axis and a recess with a fluid inlet,—a nozzle needle which is arranged axially movably in the recess in such a way that a fluid flow through at least one injection opening is prevented in a closed position of the nozzle needle and, otherwise, a fluid flow through the injection opening is released, and the nozzle needle has an end side which faces away from the injection opening,—a chamber which is formed in the injector body and adjoins an end side of the nozzle needle, which end side faces away from the injection opening,—a throttle module which is arranged in the chamber, a fluid feed chamber which is coupled hydraulically to the fluid inlet, a control space which is coupled hydraulically to the fluid feed chamber via an inflow throttle for setting a pressure force which can be applied to the pressure needle, and a valve chamber which is coupled hydraulically to the control space via an outflow throttle for receiving a valve which is configured for discharging fluid into a fluid return line being formed in the throttle module, and—a control module which is arranged in the chamber, is adjacent to the throttle module and in which the fluid return line is arranged, precisely one first and one second sealing edge being formed between the throttle module and the injector body and/or the control module, and a further hydraulic coupling of the fluid feed chamber to the control space being suppressed by means of the first sealing edge and a further hydraulic coupling of the fluid feed chamber to the valve chamber being suppressed by means of the second sealing edge, and a third sealing edge being formed between the injector body and the control module, by means of which third sealing edge a hydraulic coupling of the fluid feed chamber to the fluid return line is suppressed. 
         [0008]    According to a further embodiment, the first and the second sealing edges can be formed on the throttle module. According to a further embodiment, the first sealing edge can be formed at an axial end of the throttle module, which axial end faces the nozzle needle, and the second sealing edge is formed at an axial end of the throttle module, which axial end faces away from the nozzle needle. According to a further embodiment, the first sealing edge can be formed on the injector body. According to a further embodiment, the second sealing edge can be formed on the control module. According to a further embodiment, the first and/or the second sealing edge can be formed as cutting edges. 
         [0009]    According to another embodiment, an injection valve may have an actuator unit and an injector assembly as described above, wherein the actuator unit is coupled to the injector assembly in such a way that the injector assembly can be actuated by means of the actuator unit. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0010]    Exemplary embodiments are explained in greater detail in the following text using the diagrammatic drawings, in which: 
           [0011]      FIG. 1  shows a longitudinal section through an injection valve having an injector assembly, and 
           [0012]      FIG. 2  shows a detailed view of the injector assembly in a longitudinal section. 
       
    
    
     DETAILED DESCRIPTION 
       [0013]    According to one aspect, an injector assembly for an injection valve, has an injector body with a central longitudinal axis and a recess with a fluid inlet, a nozzle needle which is arranged axially movably in the recess in such a way that a fluid flow through at least one injection opening is prevented in a closed position and, otherwise, a fluid flow through the injection opening is released, and the nozzle needle has an end side which faces away from the injection opening, a chamber which is formed in the injector body and adjoins an end side of the nozzle needle, which end side faces away from the injection opening, a throttle module which is arranged in the chamber, a fluid feed chamber which is coupled hydraulically to the fluid inlet, a control space which is coupled hydraulically to the fluid feed chamber via an inflow throttle for setting a pressure force which can be applied to the nozzle needle, and a valve chamber which is coupled hydraulically to the control space via an outflow throttle for receiving a valve which is configured for discharging fluid into a fluid return line being formed in the throttle module, and a control module which is arranged in the chamber, is adjacent to the throttle module and in which the fluid return line is arranged. Precisely one first and one second sealing edge are formed between the throttle module and the injector body and/or the control module. A further hydraulic coupling of the fluid feed chamber to the control space is suppressed by means of the first sealing edge and a further hydraulic coupling of the fluid feed chamber to the valve chamber is suppressed by means of the second sealing edge. A third sealing edge is formed between the injector body and the control module, by means of which third sealing edge a hydraulic coupling of the fluid feed chamber to the fluid return line is suppressed. 
         [0014]    Together with an actuator unit, the injector assembly can, for example, form the injection valve. 
         [0015]    This has the advantage that the throttle module can achieve small dimensions. A small axial length of the throttle module and, as a consequence, a small axial extent of the injector assembly can therefore be achieved. Small recesses for the throttles in the throttle module are therefore also possible. Moreover, favorable flow conditions of the fluid in the throttle module and therefore low abrasion of the throttle module can also be achieved. Hardening of the throttle module can therefore be dispensed with. Moreover, as a result of the small number of sealing edges, high component strength and lower sensitivity of the throttle module to external mechanical influences can be achieved. The dimensions of the fluid feed chamber, the control space and the valve chamber can likewise be very small, as a result of which the machining outlay for these chambers can be very low. Overall, low costs can be achieved for the throttle module and therefore for the entire injector assembly. 
         [0016]    In one embodiment, the sealing edges are formed on the throttle module. Simple production of the sealing edges is therefore possible. The throttle module is not overdetermined with regard to its sealing edges. 
         [0017]    In a further embodiment, one of the sealing edges is formed at an axial end of the throttle module, which axial end faces the nozzle needle, and the other of the sealing edges is formed at an axial end of the throttle module, which axial end faces away from the nozzle needle. A simple formation of the throttle module is therefore possible. 
         [0018]    In a further embodiment, the first sealing edge is formed on the injector body and/or the second sealing edge is formed on the control module. Simple production of the sealing edges is therefore possible. 
         [0019]    In a further embodiment, the sealing edges are formed as cutting edges. Particularly satisfactory sealing properties of the sealing edges can therefore be achieved. 
         [0020]    According to a second aspect, an injection valve may have an actuator unit and an injector assembly according to the first aspect. The actuator unit is coupled to the injector assembly in such a way that the injector assembly can be actuated by means of the actuator unit. 
         [0021]      FIG. 1  shows an injection valve  10  having an injector assembly  14  and an actuator unit  16 . 
         [0022]    The injector assembly  14  has an injector body  12  with a central longitudinal axis L and a recess  32 . The injector body can be configured in one piece or in multiple pieces. A nozzle needle  34  is arranged in the recess  32  of the injector body  12 . The nozzle needle  34  can be configured in one piece or in multiple pieces. 
         [0023]    The actuator unit  16  is arranged in the injector body  12 . The actuator unit  16  can be configured, in particular, as a piezoelectric actuator with a stack of piezoelectric elements, and its axial extent changes as a function of the electric voltage which is applied. The electric voltage is applied to the actuator unit via a connector socket. The actuator unit  16  is connected to a transmission means  20  which is likewise arranged in the injector body  12 . The actuator unit  16  and the transmission means  20  form an actuating drive for the nozzle needle  34 . 
         [0024]    Furthermore, the injector body  12  comprises a high pressure connection  18 , via which, in the mounted state, the injection valve  10  is connected to a high pressure circuit (not shown) of a fluid. 
         [0025]    A chamber  22  is arranged in the recess  32  of the injector body  12 . The connection between the high pressure connection  18  and the chamber  22  takes place via a fluid inlet  23 . A throttle module  24  and a control module  26  are arranged in the chamber  22 , the structure and function of which modules  24 ,  26  will be described in detail further below. A valve  28  which is coupled to the transmission means  20  and has a valve body  29  and a valve spring  30  is arranged in the throttle module  24  and the control module  26 . Depending on the form of the valve body  29 , the valve  28  can also be configured without a valve spring  30  in further embodiments (not shown). This applies, in particular, when the valve body  29  is configured as a ball. If the valve  28  is configured without a valve spring  30 , the throttle module  24  can be of very small configuration. 
         [0026]    Fluid return lines  31  which make a hydraulic connection possible to a tank (not shown) of the vehicle are arranged in the control module  26 . Depending on the position of the valve  28 , the chamber  22  is coupled hydraulically to the fluid return lines  31  or is decoupled hydraulically from the latter. 
         [0027]    Furthermore, the injection valve  10  comprises a nozzle body  35  which is connected to the injector body  12  by means of a nozzle clamping nut  36 . One or more injection openings  52  is/are arranged in the nozzle body  35  at the end which faces away from the actuator unit  16 . 
         [0028]    The nozzle needle  34  has an end side  38  which faces the chamber  22 . In its region which faces the at least one injection opening  52 , the nozzle needle  34  has a shaft section  44 . At its end which faces the actuator unit  16 , the shaft section  44  of the nozzle needle  34  has a nozzle needle shoulder  45  which is in contact with fluid which is at approximately the pressure of the high pressure circuit. The nozzle needle shoulder  45  is configured in such a way that the force which is caused by the pressure of the fluid has an opening action on the nozzle needle  34 . 
         [0029]    Furthermore, a cavity  46  is formed in the injector body  12 , which cavity  46  receives a nozzle spring  48  which is supported at one end on a shoulder  50  of the cavity  46  and at the other end prestresses the nozzle needle  34  in such a way that the latter assumes a closed position which is assigned to it and in which it suppresses the fluid flow through the at least one injection opening  52  which is arranged in the nozzle body  35 . 
         [0030]    The nozzle needle position depends on the balance of the forces which, caused by the pressure of the fluid, act on the nozzle needle shoulder  45  and on the tip of the nozzle needle  34 , and secondly on the spring force of the nozzle spring  48  and the force as a result of the fluid which is situated in the chamber  22  and the force which is caused as a result and is introduced via the end side  38  of the nozzle needle  34  in the closing direction of the nozzle needle  34 . 
         [0031]    As is shown in  FIG. 2 , the throttle module  24  is of substantially cylindrical configuration with a module body  53  and extends in the direction of the longitudinal axis L in the chamber  22  of the injector body  12 . 
         [0032]    A fluid feed chamber  54  is formed in the throttle module  24 , which fluid feed chamber  54  is arranged as an annular gap between the body of the throttle module  24  and the injector body  12  and is coupled hydraulically to the fluid inlet  23 . 
         [0033]    At its end which faces the end side  38  of the nozzle needle  34 , the throttle module  24  has a control space  56  which forms a part of the chamber  22 , and via which control space  56  a pressure force can be applied to the nozzle needle  34  by means of the fluid, by means of which pressure force a fluid flow through the at least one injection opening  52  is prevented in the closed position of the nozzle needle  34  and, otherwise, a fluid flow through the at least one injection opening  52  is released. 
         [0034]    Facing the control module  26 , a valve chamber  58  is formed in the throttle module  24 , in which valve chamber  58  at least part of the valve body  29  and the valve spring  30  of the valve  28  are arranged. 
         [0035]    The fluid feed chamber  54  is connected hydraulically to the control space  56  via an inflow throttle  60 . Furthermore, an outflow throttle  62  is arranged in the module body  53  of the throttle module  24  between the control space  56  and the valve chamber  58 , by which outflow throttle  62  the control space  56  is coupled hydraulically to the valve chamber  58 . 
         [0036]    The valve  28 , in particular the valve body  29 , can be actuated via the actuator unit  60 , and can close or open a sealing seat  63  which is formed on the control module  26 . The valve body  29  is restored by means of the valve spring  30  which is configured as a helical spring. In the further embodiments, in which the valve  28  is configured without a valve spring  30 , the valve body  29  is restored by means of a hydraulic force which acts on it. 
         [0037]    A first sealing edge  64  is formed between the throttle module  24  and the injector body  12 , to be precise at an axial end of the throttle module  24 , which axial end faces the nozzle needle  34 . 
         [0038]    A further hydraulic coupling between the fluid feed chamber  54  which is configured as an annular gap and the control space  56  can thus be prevented, as a result of which it is possible to fix the fluid feed into the control space  56  via the dimensioning of the inflow throttle  60  and therefore, when the valve  28  is closed, to fix the pressure rise in the control space  56 . The first sealing edge  64  is preferably configured as a cutting edge, since a particularly satisfactory sealing action can therefore be achieved between the throttle module  24  and the injector body  12 . 
         [0039]    A second sealing edge  66  is formed between the throttle module and the control module  26 . The sealing edge  66  is preferably arranged at an axial end of the throttle module  24 , which axial end faces away from the nozzle needle  34 . A further hydraulic coupling between the fluid feed chamber  54  and the valve chamber  58  can be prevented by means of the second sealing edge  66 . This is of significance, in particular, when the valve  28  is open, that is to say the valve body  29  is raised up from the sealing seat  63 . In this case, unintended outflow of the fluid from the fluid feed chamber  54  via the valve chamber  58  to the fluid return line  31  can be avoided by means of the second sealing edge  66 . 
         [0040]    A third sealing edge  68  is formed between the injector body  12  and the control module  26 . A direct hydraulic coupling of the fluid feed chamber  54  to the fluid return line  31  can be suppressed by means of the third sealing edge  68 . 
         [0041]    As a result of the formation of the first sealing edge  64  at the axial end of the throttle module  24 , which axial end faces the nozzle needle  34 , and the formation of the second sealing edge  66  at the axial end of the throttle module  24 , which axial end faces away from the nozzle needle  34 , it is possible to firstly configure the throttle module  24  very simply, since, in particular, simple production of the sealing edges  64 ,  66  is possible. Secondly, the throttle module  24  is not overdetermined with regard to its sealing edges  64 ,  66 . Relatively high tolerances can therefore be permitted during the production of the throttle module  24 , in particular with regard to the tolerances for the sealing edges  64 ,  66 . Moreover, the simple cylindrical configuration of the throttle module  24  permits small dimensions of the throttle module  24  and high component strength. As a result of a small axial extent of the throttle module  24  and therefore a small axial extent of the injector assembly  14 , a small axial extent of the entire injection valve  10  becomes possible. Moreover, it is possible for the favorable arrangement in flow terms, in particular, of the inflow throttle  60  and the outflow throttle  62  to achieve a situation where only a low eddy formation of the fluid in the control space  56  and therefore low abrasive wear of the module body  53  of the throttle module  24  take place. Hardening of the throttle module  24  can therefore be dispensed with. 
         [0042]    Satisfactory sealing properties of the sealing edges are possible as a result of the configuration of the sealing edges  64 ,  66  as cutting edges. 
         [0043]    In the following text, the function of the injection valve  10  is to be described briefly: 
         [0044]    By activation of the actuator unit  16  which is configured as a piezoelectric actuator, the actuator unit  16  extends and the valve body  29  is raised up from the sealing seat  63  on the control module  26  via the transmission means  20 . A hydraulic connection from the control space  56  via the valve chamber  58  to the fluid return line  31  is therefore released and the pressure in the control space  56  drops. The equilibrium of forces at the nozzle needle  34  is therefore changed in such a way that the nozzle needle  34  moves into the control space  56  in the direction of the actuator unit  16 , as a result of which the at least one injection opening  52  in the nozzle body  35  is released. If the injection valve  10  is configured as a fuel injection valve, an injection of fuel into a combustion chamber of an internal combustion engine can therefore take place. 
         [0045]    As soon as the injection is to be ended, the actuator unit  16  is deactivated, as a result of which the valve body  29  comes into contact again with the sealing seat  63  in the control module  26 . The hydraulic coupling between the control space  56  and the fluid return line  31  is therefore interrupted. As a result of the feed of fluid from the fluid inlet  23  via the fluid feed chamber  54  and the inflow throttle  60  into the control space  56 , the pressure in the control space  56  rises, as a result of which the valve needle  34 , optionally with the assistance of the nozzle spring  48 , is moved away from the actuator unit  16  in the axial direction. The nozzle needle  34  therefore passes into a closed position and the fluid flow through the at least one injection opening  52  is suppressed. The assistance of the nozzle spring  48  for closing the nozzle needle  34  is of significance, in particular, during the starting phase of the internal combustion engine and with regard to an increased functional reliability of the closing operation of the nozzle needle  34 . 
         [0046]    As a result of the formation of the first and second sealing edges  62 ,  64  on the throttle module  24 , reliable control of the fluid from the fluid feed chamber  54  to the control space  56  and from the control space  56  via the valve chamber  58  to the fluid return line  31  can be achieved, in particular. 
         [0047]    In further embodiments which are not shown here in detail, it is also possible to form the first sealing edge  64  in the injector body  12  instead of in the throttle module  24 , the second sealing edge in the control module  26  instead of in the throttle module  24 , and the third sealing edge  68  in the control module  26  instead of in the injector body  12 .