Abstract:
An assembly includes: a first component; a second component enclosed by the first component; a diaphragm that covers a radial gap between the first and second components and is fixed in each case in a sealed manner; and a volume of a medium that is enclosed by the first and second components and the diaphragm. For the purpose of achieving a simple filling process of the assembly with the medium at a reliable sealing of the enclosed volume, even in the case of high, swelling pressures acting upon the assembly, in one of the components a filling valve is situated that opens towards the volume, which filling valve is situated as a check valve having spring resetting in a filling channel running in the component.

Description:
BACKGROUND OF THE INVENTION 
       [0001]    1. Field of the Invention 
         [0002]    The present invention relates to an assembly, e.g., for sealing components of a valve. 
         [0003]    2. Description of the Related Art 
         [0004]    A known assembly for sealing a force transmission element (which is described in published German patent application document DE 10 2009 047 009 A1) guided in a duct in a body is used in a fuel injector in fuel injection systems for internal combustion engines for sealing components of the valve, that are not resistant to fuel, such as the piezoelectric actuator for the valve control, from the fuel present in a valve chamber of the valve under system pressure. The valve chamber is bordered by a valve housing and a valve body that is fixed to the valve housing in a sealed manner. The valve body has a duct for a valve needle, which extends from a valve opening arranged in front of the valve chamber up to the actuator. In the area of the duct, the valve needle carries a slide ring, fixed on it, which borders a narrow radial gap with the valve body within the duct. In order to prevent the passage of the fuel through this radial gap, the end face of the valve body bordering the valve chamber is covered by an annular diaphragm, which with its inner edge is fixed on the slide ring and its outer edge on the valve body. The region on the valve body covered by the diaphragm is filled with a medium. 
         [0005]    The medium has a yield stress which is selected as a function of the fuel pressure prevailing in the valve chamber, for example, a soft mass having a high yield stress, such as a Bingham fluid, viscous silicone oil or transformer oil. In order to fill the covering region of the diaphragm with the medium, a chamber is present in the valve body, which subdivides the valve body into a front and a rear body part. In the front body part, a connection to the covering region is produced and in the rear body part, using the slide ring, the sliding guide of the valve needle in the valve body is implemented. The filling of the chamber with the medium takes place via a filling hole inserted into the valve needle, which opens out into the chamber. After the filling in of the medium, the filling hole is closed by pressing in a ball. 
       BRIEF SUMMARY OF THE INVENTION 
       [0006]    The assembly according to the present invention has the advantage that, using the filling valve present in one of the components, on the one hand, the constructive design of the assembly for filling with medium is clearly simplified, and on the other hand, the filled medium volume is reliably sealed even in the case of high and swelling pressures acting upon the assembly. In particular, when the filling valve is acting as a check valve, the increase in the pressure in the medium volume leads to an additional pressure on the valve member of the check valve and reinforces the closing force of the valve. By contrast to the known sealing of the enclosed medium volume using a ball pressed into the component, a relatively soft material does not have to be selected for the purpose of pressing in the ball, but rather, a quite hard material may advantageously be used. The installation of the filling valve is simple and has high process reliability. The filling process, for which venting the assembly is required, may be carried out advantageously using the filling valve in two stages and, if necessary, also in two different process stations, by first venting the assembly by opening the filling valve, and subsequently inserting the medium by renewed opening of the filling valve. 
         [0007]    According to one advantageous specific embodiment of the present invention, the filling valve is situated in a filling channel which runs in the one component and is accessible at the outside of the assembly. Consequently, the integrated filling valve remains easily accessible for the venting and the filling process, and by a corresponding design of the filling channel, one is able to implement at the same time components of the filling valve such as valve seat and valve chamber having inlet and outlet. 
         [0008]    For this purpose, according to one advantageous specific embodiment of the present invention, the filling channel is developed as a stepped hole having a first boring section and a second boring section having a larger diameter than the first, and, at the transition of the boring sections, a valve seat for a valve member. The valve member is preferably a steel ball coated with PTFE, and the valve seat, for optimal sealing of the ball, has an angle of slope a of between 5° and 60°, measured with respect to the axis of the bores. 
         [0009]    According to one advantageous specific embodiment of the present invention, the stepped hole has a third boring section adjoining the second boring section, the third boring section, having an enlarged diameter compared to the second boring section, being situated eccentrically to the boring axis. A spring arm subjecting the valve member or the ball to pressure in the direction of the valve seat is fastened in the third boring section. The spring arm implements a thin-profile return spring or valve closing spring of the filling valve, having a small installation space and having sufficient closing force, pressure acting on the assembly being advantageously transmitted by the medium volume to the spring arm and the valve member, and increasing the closing force of the valve. 
         [0010]    According to one advantageous specific embodiment of the present invention, the spring arm is stamped out of the shell bottom as a part of a shell-shaped spring element having a shell bottom and a shell edge, and the spring element is placed into the third boring section and fixed by pressing in or welding in the shell edge. Such a spring element may be made cost-effectively as a simple stamped and bent part of high-strength stainless steel. The closing force of the valve may be set by establishing a certain press-in depth of the spring element into the third boring section. 
         [0011]    The assembly according to the present invention is used advantageously in valves for metering fluid, particularly for the dosing injection of fuel in fuel injection systems of internal combustion engines, and, in this case, is drawn upon for generating a sealing assembly for sealing a valve chamber from fluid outflow or an hydraulic coupler for compensating for different thermal expansions of the valve housing and a force-transmitting element that is axially supported in the valve housing, such as a piezoelectric actuator or a magnetostrictive actuator and a valve needle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0012]      FIG. 1  shows a valve for metering fluid, in partial section. 
           [0013]      FIG. 2  shows an enlarged illustration of a longitudinal section of the lower part of the valve shown in a side view in  FIG. 1 . 
           [0014]      FIG. 3  shows an enlarged illustration of cutout III in  FIG. 2 . 
           [0015]      FIG. 4  shows a view from below of a spring element in the valve in the direction of arrow IV in  FIG. 3 . 
           [0016]      FIG. 5  shows a longitudinal section of a hydraulic coupler in the valve according to  FIG. 1 . 
           [0017]      FIG. 6  shows an identical representation as in  FIG. 5 , showing a modified hydraulic coupler. 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    The novel assembly introduced here is described below in connection with its insertion into a valve for metering a fluid, such as into a fuel injector for fuel in a fuel injection system for internal combustion engines. In such a valve as shown in  FIG. 1 , the assembly may be used advantageously for sealing a valve chamber in the valve housing, as shown in  FIGS. 2 and 3 , and/or as an hydraulic coupler situated in the valve housing, as shown in  FIGS. 4 and 5 . 
         [0019]    The assembly ( FIGS. 2 through 6 ) has a first component  11 , a second component  12  enclosed by first component  11 , a flexible, for instance, annular diaphragm  13  which is secured on first and second components  11 ,  12  and covers a radial gap  14  that is present between components  11 ,  12 , and a volume  15  of a medium enclosed by components  11 ,  12  and diaphragm  13 . The medium is a liquid or a soft and kneadable substance, but may also be a gas in special cases of application. For the introduction of the medium, a filling valve is situated in one of components  11 ,  12 , which opens in the direction of enclosed volume  15 . Filling valve  16  is developed as a check valve having spring resetting and is situated in a filling channel  17  running in first component  11  or in second component  12 . As may be seen in the sectional representation of the enlarged cutout according to  FIG. 3 , filling channel  17  is developed having a first boring section  181  and a second boring section  182  that is greater in diameter compared to the former, as well as a third boring section  183  adjacent to second boring section  182 . At the transition from the first to the second boring section  181 ,  182 , a valve seat  19  is developed for a spring-loaded valve member  20 . Third boring section  183  has a larger diameter compared to the diameter of second boring section  182  and is situated eccentrically to the boring axis. In third boring section  182 , a spring arm  21  is fixed that stresses valve member  20  in the valve closing direction, i.e. 
         [0020]    in the direction of valve seat  21 . Valve member  20  is preferably a steel ball coated with PTFE, and valve seat  19 , for optimal sealing of the ball, has an angle of slope a of between 5° and 60°, measured with respect to the axis of the bores. Spring arm  21  lying with force-locking on valve member  20  is part of a shell-shaped spring element  22  having a shell bottom  221  and a shell edge  222  ( FIGS. 3 and 4 ) and is stamped out of shell bottom  221 . To set the spring force of spring arm  21  that acts upon valve member  20 , spring element  22  is placed at a height H ( FIG. 3 ) into third boring section  183  and fastened there, which takes place by pressing in or welding in shell edge  222 . Spring element  22  is a stamped and bent part made high-strength spring steel. Because of the eccentricity of third boring section  183 , as large as possible a bending length b ( FIG. 4 ) of spring arm  21  is achieved. 
         [0021]    To insert the medium after assembling the assembly, the assessment is first vented, that is, volume  15  held in reserve for the medium is evacuated between components  11  and  12  and diaphragm  13 , for which filling valve  16  is opened. For this, an axial displacement force is applied to valve member  20  through first boring section  181  of stepped hole  18 , which lifts valve member  20  off valve seat  19  against the resetting force of spring arm  21 . After the venting of the assembly, filling valve  16  closes on valve member  20  by the omission of the displacement force. Subsequently, via a filling tube introduced up to first boring section  181 , the medium is reliably inserted, using a pressure which exceeds the spring force of spring arm  21 , into the assembly, so that the specified volume  15  is completely filled with the medium. The closing force acting upon valve member  20  is now increased by the pressure prevailing in enclosed volume  15 . 
         [0022]    The valve for metering a fluid, particularly fuel, in which the assembly described is preferably used, is shown in  FIG. 1  in partial section. The valve has a valve housing  30 , in a known manner, in whose one housing end a valve-seat support  31  is securely inserted. At the free end of valve-seat support  31  facing away from valve housing  30 , a metering opening  32  is situated ( FIG. 2 ) which is able to be controlled by a closure head  331  formed on a valve needle  33  in connection with a valve seat  311  developed on valve-seat support  31 . Valve needle  33  is operated by a piezoelectric actuator or magnetostrictive actuator  34  against the restoring force of valve closing spring  35 , actuator  34  being connected to a hydraulic coupler  36 , which is supported in valve housing  30  Cardanically. For this purpose, the other end of valve housing  30  is closed using a connecting piece  37 , in which an inlet bore  39  is developed having a connection piece  38  for supplying fluid. Actuator  35  and hydraulic coupler  36  are situated in a housing tube  40  that is fastened to connecting piece  37 , and between valve housing  30  and housing tube  40  there is an annular gap  49 , which connects inlet bore  39  in connecting piece  37  to a valve chamber  41  that is connected upstream of metering opening  32  in valve-seat support  31 . 
         [0023]    As shown In  FIGS. 2 and 3 , the assembly described above is used for sealing valve chamber  41 , and, with that, housing tube  40  including non-fluid or fluid-resistant actuator  34 , from the fluid located in valve chamber  41 . In this context, first component  11  forms a valve body  42 , bordering valve chamber  41 , which is on one end connected to the end of housing tube  40  and on the other end to valve-seat support  31 , securely in each case, and fluid-tight (welding seams  45  and  46  in  FIGS. 2 and 3 ). Second component  12  forms valve needle  33 , which is guided through valve body  42  while leaving radial gap  14 . Annular, flexible diaphragm  13  is fastened by its inner edge to valve needle  33  and by its outer edge on valve body  42 , in each case fluid-tight, which is symbolized by welding seams  43  and  44  in  FIGS. 2 and 3 . From a standpoint of production engineering, valve needle  33  carries a fixed slide ring  47  for guiding it in valve body  42 , so that radial gap  14  is present between slide ring  47  representing a part of valve needle  33  and valve body  42 , and the inner edge of diaphragm  13  is fastened to slide ring  47 . Filling channel  17  including filling valve  16  is situated in valve body  42  and enclosed volume  15  of the medium is concentrated in a covering region  56  covered by diaphragm  13  on valve body  42 . The medium in enclosed volume  15  is a soft substance having a high yield stress, for instance, a Bingham fluid, a viscous silicone oil, soft or kneadable material, such as an elastomer or transformer oil. 
         [0024]    As shown in  FIGS. 5 and 6 , the assembly described in the valve according to  FIG. 1  is also used for implementing hydraulic coupler  36 . For this, first component  11  forms a pot-shaped coupling housing  50 , having a pot bottom  501  and a pot jacket  502 , which is supported Cardanically in a recess  51  in connecting piece  37 . Second component  12  forms a coupling member  52  that is axially displaceable, and able to be acted upon by a force transmission element, in this case actuator  34 , which has a piston  53 , guided slidingly in a coupling housing  50  and a coupling bolt  54  that is rigidly connected to piston  53  for connecting the force transmission element, in this case actuator  34 . Piston  53  borders radial gap  14  with pot jacket  502  of coupling housing  50  and with pot bottom  501  a coupling gap  55 . Filling valve  16  is situated in coupling member  52 , and enclosed volume  15  of the medium is distributed via radial gap  14  to covering region  56  diaphragm  13  fixed on coupling housing  50  and coupling member  52  and to coupling gap  55 . As the medium, a fluid is used, such as an hydraulic oil. 
         [0025]    As shown in  FIG. 5 , the fixing of diaphragm  13  on the coupling member side takes place on coupling bolt  54 . Coupling bolt  54  is fastened in a recess  57  present in piston  53 , and, with the base of recess  57 , it borders a hollow space  58 , which is connected to covering region  56 . Filling channel  17 , having filling valve  16  integrated into it, runs in coupling bolt  54  and opens out into hollow space  58 , so that volume  15 , enclosed by coupling housing  50 , piston  53  and diaphragm  13 , of the medium extends into hollow space  58 . Coupling bolt  54 , at its end protruding from piston  53 , is provided with a hollow  59  and actuator  34  is provided with a force transmission plate  60 , at which a lug  61  that dips into hollow  59  in coupling bolt  54  is connected in an attached form. Lug  61  is fixed in hollow  59 , by being pressed in, for example. Actuator  34  is able to be supplied with current via an electrical plug connector  48  that is connected in an attached form to valve housing  30 . 
         [0026]    The unit of actuator  34  and hydraulic coupler  36  is mounted, under the effect of valve closing spring  35 , with force-locking between valve needle  33  and connecting piece  37 . If a change in temperature causes a different expansion of actuator  34  and valve housing  30 , then the pressure of piston  53  on coupler gap  55  increases. The increased pressure in coupler gap  55  causes the medium to be expelled from coupler gap  55 , and it is displaced via radial gap  14  into covering region  56  of diaphragm  13 . If the piston pressure on coupler gap  55  decreases again due to the temperature change, diaphragm  13  generates a sufficiently high pressure force to press back the medium from covering region  56  into coupler gap  55  again, via radial gap  14 , while simultaneously displacing piston  53 . 
         [0027]    Hydraulic coupler  36 , shown in longitudinal section in  FIG. 6 , is modified in comparison to hydraulic coupler  36  described in  FIG. 5  to the extent that, in addition to diaphragm  13 , on the outside of coupling housing  50 , facing away from coupling gap  55 , 
         [0028]    a second diaphragm  62  is situated which spans pot bottom  501  of coupling housing  50  and is fixed, in a medium-tight manner, on pot jacket  502  of coupling housing  50 , that is, liquid-tight. Between second diaphragm  62  and coupling housing  50  there remains an equalization chamber  63  which is in connection to coupling gap  55  via at least one bore  64  in pot jacket  502  and via radial gap  13 . Alternatively, equalization chamber  63  may also be connected directly to coupling gap  55  via an axial bore provided in pot bottom  501 . Equalization chamber  63  is also filled with medium via the existing connection to covering region  56  of diaphragm  13  to hollow space  58  at the bottom of recess  57  in piston  53 . Equalization chamber  63  increases the altogether enclosed volume  15  of the medium, so that greater thermal expansion differences of valve housing  30  and the unit of actuator  34  and valve needle  33  ( FIG. 1 ) are able to be compensated for. In all other respects, hydraulic coupler  36  according to  FIG. 6  corresponds to that shown in  FIG. 5 , so that identical components have been provided with matching reference numerals.