Abstract:
An injection valve includes an injector component having an injector body including a recess hydraulically coupled to a high-pressure circuit of a fluid, and a nozzle needle moveably disposed injector body recess for preventing fluid flow through at least one injection opening in a closed position, and otherwise for releasing the fluid flow; an actuator unit disposed in the injector body recess and having an actuator element disposed in an actuator housing including an end face at an axial end facing the injection opening, which end face is mechanically coupled to a stage implemented in the injector body via a ring element disposed axially between the end face and the stage. At least two radial through passages are disposed opposite each other in the ring element, designed for hydraulically coupling between a ring interior disposed within the ring element and a ring exterior disposed outside of the ring element.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a U.S. National Stage Application of International Application No. PCT/EP2010/066739 filed Nov. 3, 2010, which designates the United States of America, and claims priority to German Application No. 10 2009 051 677.8 filed Nov. 3, 2009, the contents of which are hereby incorporated by reference in their entirety. 
     TECHNICAL FIELD 
     This disclosure relates to an injection valve. 
     BACKGROUND 
     Ever more stringent legal regulations with regard to the admissible pollutant emissions of internal combustion engines which are arranged in motor vehicles make it necessary to implement various measures for reducing pollutant emissions. One approach here is to reduce the pollutant emissions generated by the internal combustion engine. 
     Correspondingly reduced pollutant emissions can be attained if the fuel is metered in at very high pressure. In the case of diesel internal combustion engines, the fuel pressures are up to over 2000 bar. Such high pressures place high demands on the construction of an injection valve. At the same time, high demands are placed on the actuator unit for the injection valve. 
     SUMMARY 
     In one embodiment, an injection valve comprises: an injector assembly with an injector body which has a recess, which extends in the direction of a longitudinal axis, of the injector body, which recess can be hydraulically coupled to a high-pressure circuit of a fluid, and with a nozzle needle arranged in an axially movable manner in the recess of the injector body, which nozzle needle is designed to prevent a fluid flow through at least one injection orifice when in a closed position and to otherwise permit the fluid flow; an actuator unit which is arranged in the recess of the injector body and which has an actuator housing in which an actuator element is arranged, and the actuator housing has, on an axial end facing towards the injection orifice, an end surface which is mechanically coupled to a step formed in the injector body; and a ring element arranged axially between the end surface and the step, wherein in the ring element there are arranged at least two passage orifices which are situated opposite one another and which extend radially and which are designed to provide hydraulic coupling between a ring interior space arranged within the ring element and a ring exterior space arranged outside the ring element. 
     In a further embodiment, at least one of the passage orifices is formed as a slot or groove in the ring element. In a further embodiment, the ring element has a multiplicity of passage orifices which are arranged point-symmetrically with respect to one another about the longitudinal axis. In a further embodiment, the ring element is formed as a hexagon with six sides, and one of the passage orifices is formed in each of the sides of the hexagon. 
     In another embodiment, an injection valve comprises: an injector assembly with an injector body which has a recess, which extends in the direction of a longitudinal axis, of the injector body, which recess can be hydraulically coupled to a high-pressure circuit of a fluid, and with a nozzle needle arranged in an axially movable manner in the recess of the injector body, which nozzle needle is designed to prevent a fluid flow through at least one injection orifice when in a closed position and to otherwise permit the fluid flow; an actuator unit which is arranged in the recess of the injector body and which has an actuator housing in which an actuator element is arranged, and the actuator housing has, on an axial end facing towards the injection orifice, an end surface which is mechanically coupled to a step formed in the injector body; and a ring element arranged axially between the end surface and the step, wherein in the step there is arranged at least one radially extending passage recess which is designed to provide hydraulic coupling between a ring interior space arranged within the ring element and a ring exterior space arranged outside the ring element. 
     In a further embodiment, in the step there is arranged a multiplicity of passage recesses which are arranged point-symmetrically with respect to one another about the longitudinal axis. In a further embodiment, at least one of the passage recesses is formed as a groove, as a channel, as an annular groove or as a hole in the step. In a further embodiment, the ring element is formed from a wire ring with a gap, wherein the gap is formed as a passage orifice 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Example embodiments will be explained in more detail below with reference to figures, in which: 
         FIG. 1  shows a longitudinal section through an injection valve, 
         FIG. 2  shows a detail view of the injection valve in a longitudinal section, 
         FIG. 3  shows a detail view of a ring element of the injection valve in an example embodiment, 
         FIG. 4  shows a detail view of the ring element of the injection valve in a further example embodiment, and 
         FIG. 5  shows a detail view of the ring element of the injection valve in a further example embodiment. 
     
    
    
     DETAILED DESCRIPTION 
     Some embodiments provide an injection valve which is simple and cheap to produce and the mechanical loading of which is limited. 
     According to a first embodiment, injection valve includes an injector assembly with an injector body which has a recess, which extends in the direction of a longitudinal axis, of the injector body, which recess can be hydraulically coupled to a high-pressure circuit of a fluid, and with a nozzle needle arranged in an axially movable manner in the recess of the injector body, which nozzle needle is designed to prevent a fluid flow through at least one injection orifice when in a closed position and to otherwise permit the fluid flow, an actuator unit which is arranged in the recess of the injector body and which has a tubular housing in which the actuator element is arranged, and the tubular housing has, on an axial end facing towards the injection orifice, an end surface which is mechanically coupled to a step formed in the injector body, and a ring element arranged axially between the end surface and the step. In the ring element there are arranged at least two passage orifices which are situated opposite one another and which extend radially and which are designed to provide hydraulic coupling between a ring interior space arranged within the ring element and a ring exterior space arranged outside the ring element. 
     An injection valve of such design may provide pressure equalization between the ring interior space and the ring exterior space. The pressure profiles in the ring interior space and the ring exterior space can therefore be aligned with one another. The dynamics of the pressure profile in the ring interior space and the ring exterior space can thereby be kept low. The mechanical loading resulting from pressure fluctuations in the injection valve and the loading of components of the injection valve can thereby be kept low. 
     In one embodiment, at least one of the passage orifices is formed as a slot or groove in the ring element. Such passage orifices may have the advantage of simple production. Furthermore, the ring element with the passage orifices can have high mechanical stability. 
     In a further embodiment, the ring element has a multiplicity of passage orifices which are arranged point-symmetrically with respect to one another about the longitudinal axis. This may provide pressure equalization between the ring interior space and the ring exterior space in a highly effective manner. It may thereby be possible for the pressure profiles in the ring interior space and the ring exterior space to be aligned with one another in a highly effective manner independently of the azimuth. The dynamics of the pressure profile in particular in the ring exterior space can thereby be kept low, such that the loading of components of the injection valve can be low. 
     In a further embodiment, the ring element is formed as a hexagon with six sides. One of the passage orifices is formed in each of the sides of the hexagon. Such ring element may be simple and inexpensive to produce. Furthermore, pressure equalization between the ring interior space and the ring exterior space may be possible in a highly effective manner. The pressure profiles in the ring interior space and the ring exterior space can thus be aligned in a highly effective manner. 
     According to another embodiment, an injection valve includes an injector assembly with an injector body which has a recess, which extends in the direction of a longitudinal axis, of the injector body, which recess can be hydraulically coupled to a high-pressure circuit of a fluid, and with a nozzle needle arranged in an axially movable manner in the recess of the injector body, which nozzle needle is designed to prevent a fluid flow through at least one injection orifice when in a closed position and to otherwise permit the fluid flow, an actuator unit which is arranged in the recess of the injector body and which has a tubular housing in which an actuator element is arranged, and the tubular housing has, on an axial end facing towards the injection orifice, an end surface which is mechanically coupled to a step formed in the injector body, and a ring element arranged axially between the end surface and the step. In the step there is arranged at least one radially extending passage recess which is designed to provide hydraulic coupling between a ring interior space arranged within the ring element and a ring exterior space arranged outside the ring element. 
     An injection valve of such design may provide pressure equalization between the ring interior space and the ring exterior space. The pressure profiles in the ring interior space and the ring exterior space can therefore be aligned with one another. The dynamics of the pressure profile in the ring interior space and the ring exterior space can thereby be kept low. The mechanical loading resulting from pressure fluctuations in the injection valve and the loading of components of the injection valve can thereby be kept low. Furthermore, the ring element can be formed without passage orifices and can have high mechanical stability. 
     In one embodiment, in the step there is arranged a multiplicity of passage recesses which are arranged point-symmetrically with respect to one another about the longitudinal axis. This may provide pressure equalization between the ring interior space and the ring exterior space in a highly effective manner. It may thereby be possible for the pressure profiles in the ring interior space and the ring exterior space to be aligned with one another in a highly effective manner independently of the azimuth. 
     In a further embodiment, at least one of the passage recesses is formed as a groove, as a channel, as an annular groove or as a hole in the step. Simple production of such passage recesses in the injector body may be possible. 
     In a further embodiment, the ring element is formed from a wire ring with a gap. The gap is formed as a passage orifice. Such ring element may be simple and inexpensive to produce. 
       FIG. 1  shows an example injection valve  10 . The injection valve  10  has an injector assembly  14  with an injector body  12  and has an actuator unit  16  arranged in the injector body  12 . 
     The actuator unit  16  is formed as a piezoelectric actuator with a stack of piezo elements. The axial extent of the actuator unit  16  varies as a function of the applied electrical voltage. The electrical voltage is applied to the actuator unit  16  via a connection socket. 
     The injector body  12  has a central longitudinal axis L and a recess  17 . The injector body  12  may be of single-part or multi-part form. A nozzle needle  18  is arranged in the recess of the injector body  12 . The nozzle needle  18  may be of single-part or multi-part form. 
     The actuator unit  16  is coupled to a transmitter  20  which is likewise arranged in the injector body  12 . The actuator unit and the transmitter  20  form an actuating drive for the nozzle needle  18 . 
     The injector body  12  furthermore comprises a high-pressure connection via which the injection valve  10  is, in the assembled state, connected to a high-pressure circuit (not illustrated) of a fluid. 
     A valve  30  which is coupled to the transmitter  20  is arranged in the recess  17  of the injector body  12 . 
     The injection valve  10  furthermore comprises a nozzle body  32  which is coupled by means of a nozzle clamping nut  36  to the injector body  12 . At the end facing away from the actuator unit  16 , one or more injection orifices  34  are formed in the nozzle body  32 . 
     The nozzle needle  18  has an end side  38  which faces toward the valve  30 . At its end facing toward the actuator unit  16 , the nozzle needle  18  has a nozzle needle shoulder  40  which is in contact with fluid which is approximately at the pressure of the high-pressure circuit. The nozzle needle shoulder  40  is formed such that the force caused by the pressure of the fluid acts so as to open the nozzle needle  18 . 
     In the injector body  12  there is furthermore formed a cavity which receives a nozzle spring  48  which at one side is supported on a shoulder of the cavity  46  and which at the other side preloads the nozzle needle  18  such that the latter assumes a closed position assigned to it, in which closed position said nozzle needle prevents the fluid flow through the at least one injection orifice  34 . 
     The functioning of the example injection valve  10  are discussed below: 
     The position of the nozzle needle  18  is dependent on the balance of forces exerted on the nozzle needle shoulder  40  and on the tip of the nozzle needle  18  by the pressure of the fluid, and secondly the spring force of the nozzle spring  48  and the force which is exerted by the pressure of the fluid and which is introduced in the closing direction of the nozzle needle  18  via the end side  38  of the nozzle needle  18 . 
     As a result of activation of the actuator unit  16  which is formed as a piezoelectric actuator, the actuator unit  16  expands, such that the valve  30  opens and fluid can flow out of the chamber above the end side  38  of the nozzle needle  18 . The nozzle needle  18  can thereby move in the direction of the actuator unit  16 , whereby the at least one injection orifice  34  is opened up. If the injection valve  10  is formed as a fuel injection valve, an injection of fuel into a combustion chamber of an internal combustion engine can take place. 
     When the injection is to be ended, the actuator unit  16  is deactivated, whereby the nozzle needle  18  is moved away from the actuator unit  16  in the axial direction. The nozzle needle  18  thereby passes into a closed position, and the fluid flow through the at least one injection orifice  34  is stopped. 
       FIGS. 1 and 2  illustrate the actuator unit  16  with a tubular actuator housing  60 . The stack of piezo elements of the piezo actuator is arranged in the actuator housing  60 . The actuator housing  60  is of cylindrical design and extends in the direction of the longitudinal axis L. The actuator housing  60  has a tube casing  62  and a base plate  64 . The base plate  64  is arranged at one axial end  65  of the tube casing  62  and therefore of the actuator housing  60 . The base plate  64  is coupled in a flexible manner to the tube casing  62  via a diaphragm  66 . The base plate  64  is formed from or has a metal. 
     The actuator housing  60  has, on the axial end  65  facing toward the injection orifice  34 , an end surface  68  which mechanically interacts with a step  70  formed in the injector body  12 . For this purpose, a ring element  72  is arranged axially between the end surface  68  and the step  70 . The ring element  72  is in the shape of a hexagon. The ring element  72  serves to set an idle stroke of the actuator unit  16  in relation to the transmitter  20  in the axial direction, such as arises during the activation of the actuator unit  16 , to a predefined value. 
     Arranged within the ring element  72  is a ring interior space  74 . Arranged outside the ring element  72  is a ring exterior space  76 . The ring exterior space  76  is sealed off with respect to the environment by means of an O ring seal  77 . 
     A plurality of radially extending passage orifices  78  are arranged in the ring element  72 . The passage orifices  78  have a typical width B_ 1  of 0.5 mm. In the embodiments shown in  FIGS. 3 and 4 , one of the passage orifices  78  is arranged in each of six sides  80  of the ring element  72 . The number of passage orifices  78  is generally at least two and may otherwise be of any desired value. In the embodiments shown in  FIGS. 3 and 4 , the ring element  72  has a plurality of passage orifices  78  which are arranged point-symmetrically with respect to one another about the longitudinal axis L. The passage orifices  78  are formed as slots or grooves. By means of the passage orifices  78 , the ring interior space  74  arranged within the ring element  72  can be hydraulically coupled to the ring exterior space  76  arranged outside the ring element  72 . At least two of the passage orifices  78  are situated opposite one another, as a result of which reliable pressure equalization between the ring interior space  74  and the ring exterior space  76  is possible via the passage orifices  78 . The pressure profiles in the ring interior space  74  and the ring exterior space  76  can thereby be aligned with one another in a very simple manner. 
     In the embodiments shown in  FIGS. 3 ,  4  and  5 , the ring element  72  is formed from a wire ring. The ring element  72  may be formed from a steel wire. The wire ring is formed such that its ends form a gap  82  with a width B_ 2  in the ring element  72 . The gap  82  is formed as one of the passage orifices  78  between the ring interior space  74  and the ring exterior space  76 . The width B_ 2  is typically at most 0.4 mm. 
     In the embodiment of the injection valve  10  shown in  FIG. 5 , at least one radially extending passage recess  84  is arranged in the step  70 . The passage recess  84  extends in the radial direction beyond the radial width of the ring element  72 . The ring interior space  74  can be hydraulically coupled to the ring exterior space  76  by means of the passage recess  84 . 
     In the embodiment of the injection valve  10  shown in  FIG. 5 , a plurality of passage recesses  84  is arranged in the step  70 , wherein each of the passage recesses  84  is assigned to one of the sides  80  of the hexagonal ring element  72 . The passage recesses  84  are in particular arranged point-symmetrically with respect to one another about the longitudinal axis L. 
     The passage recesses  84  are formed in particular as grooves, as channels, as annular grooves or as blind holes in the injector body  12 . 
     Between two activation phases of the actuator unit  16  formed as a piezo actuator, the hydraulic pressure is the same inside and outside the ring element  72 , and therefore also at the O ring seal  77 . 
     During an activation of the actuator unit  16  formed as a piezo actuator, the pressure profiles in the ring interior space  74  and the ring exterior space  76  may differ. The advantage of the passage orifices  78  in the ring element  72  or of the passage recesses  84  in the injector body  12  is basically that, in particular during an activation of the actuator unit  16 , a highly effective and fast pressure equalization between the ring interior space  74  and the ring exterior space  76  is possible. It is thereby possible for the time profiles of the pressures in the ring interior space  74  and the ring exterior space  76  to be aligned with one another in a highly effective manner. This can be achieved particularly effectively if the passage orifices  78  in the ring element  72  or the passage recesses  84  are arranged point-symmetrically with respect to the longitudinal axis L, because in this case the pressure in the ring exterior space  76  can be aligned in an effective manner, independently of the azimuth, to the pressure in the ring interior space  74 . It may thus be possible for the mechanical loading caused by pressure fluctuations in the injection valve  10 , and in particular a loading of components of the injection valve  10  outside the ring exterior space  76 , to be kept low. It may thereby also be possible in particular for a mechanical loading of the O ring seal  77  to be kept low, such that frequent exchange of the O ring seal  77  can be avoided. Exchange costs can thereby be reduced or eliminated. 
     The invention is not restricted to the example embodiments discussed above. For example, the features of the various aspects and embodiments discussed above may be combined with one another, and therefore such arrangements are also encompassed by the invention.