Abstract:
The invention relates to an anti-rotation device of a fuel lance arranged in a bore extending through a cylinder head of a cylinder head from an intake opening until a hole provided for receiving a fuel injector, the lance allowing high-pressure fuel to circulate from an intake opening of the lance until the outlet opening of the lance engaging with the intake opening of the fuel injector, the fuel lance including a nut for being screwed into the intake opening of the bore and a tubular member compressed between the nut and the injector, the lance also including the anti-rotation device. The anti-rotation device is a resilient element which is deformed by rotation of the nut, such as to be blocked between the tubular member and an inner wall of the bore, and thus prevent rotation of the tubular member when the nut is screwed.

Description:
CROSS REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application is a national stage application under 35 USC 371 of PCT Application No. PCT/EP2015/075919 having an international filing date of Nov. 6, 2015, which is designated in the United States and which claimed the benefit of FR Patent Application No. 1460771 filed on Nov. 7, 2014, the entire disclosures of each are hereby incorporated by reference in their entirety. 
     
    
     TECHNICAL FIELD 
       [0002]    The present invention relates to an anti-rotation device used in a fuel lance which supplies a fuel injector at high pressure. 
       TECHNOLOGICAL BACKGROUND OF THE INVENTION 
       [0003]    In an internal combustion engine, a fuel pump supplies each cylinder of the engine with fuel at high pressure by means of dedicated fuel injector. Typically, the fuel injector is fitted in a bore provided in a cylinder head, and a fuel lance is used to provide a fluid connection between the injector and the supply duct coming from the fuel pump. 
         [0004]    This type of assembly is known from EP0974749 and is shown in  FIG. 1 . A fuel lance  10  comprises a tubular member  22 , with a first end  46  which is designed to cooperate with the seat  16  of an injector  12 , and a second end  48  which is formed in order to define a frusto-conical seat  24 . A securing nut  26  is partially inside an end of a bore  20 , with the securing nut  26  comprising an inner end region  28  which is designed to cooperate with the seat  24 . 
         [0005]    The securing nut  26  comprises an outer threaded region  30 . The thread  30  is designed to cooperate with threads of screws formed in the end  48  of the bore  20 . In use, the securing nut  26  is secured inside the end  48  of the bore  20 . The inner end  28  of the securing nut  26  cooperates with the seat  24  of the tubular element  22 , by applying a compression force against the tubular member  22  in order to form a seal, both between the tubular member  22  and the seat  16  of the injector  12 , and between the nut  26  and the tubular member  22 . 
         [0006]    The tubular member  22  and the securing nut  26  each comprise passages which extend axially, and together define a flow path. The fuel can flow through the fuel lance  10  to the supply passage  18  of the injector  12  from a high-pressure fuel hose  34  which is secured on the securing nut  26  by means of a standard securing tube  36 . As illustrated in  FIG. 1 , the bore in the securing nut  26  extends axially, and comprises a region with a larger diameter which receives a filter element with a slot  38  designed to filter the undesirable particles which come from the flow of fuel towards the injector  12 . 
         [0007]    The head  14  comprises a passage  42  which communicates with the bore  20 , with the passage  42  allowing the low-pressure fuel to flow from the injector  12  through the bore  20 , towards a low-pressure fuel tank (not described). The securing nut  26  comprises a proximal recess in the threaded region  30 , which positions an annular sealing element  32 , designed to form a seal against the fluids, between the securing nut  26  and the wall of the head  14  which defines the bore  20 . 
         [0008]    A problem which exists concerning the high-pressure fuel supply device is that the sealing between the fuel lance and the injection nozzle requires tightening of a securing screw in the head, and transfer of the load of the screw to the fuel lance. This mechanism also gives rise to rotation of the parts, and generation of undesirable particles in the form of debris, which could lead to contamination of the fuel and wear of the components. 
         [0009]    In order to solve this problem, the invention consists of an anti-rotation device for the fuel lance, in order to prevent its rotation inside the head, and thus to transmit the required load better. 
       SUMMARY OF THE INVENTION 
       [0010]    The objective of the present invention is to solve the problems previously described by proposing a solution which is simple and easy to assemble. 
         [0011]    For this purpose, the invention proposes an anti-rotation device of a fuel lance. The lance can be arranged in a bore which extends through a cylinder head, from an intake orifice to a pit which is provided in order to receive a fuel injector. The lance is designed to allow high-pressure fuel to circulate from an intake mouth of the lance to the outlet mouth of the lance cooperating with the intake mouth of the fuel injector. The fuel lance comprises a nut which is designed to be screwed into an intake orifice in the bore, and a tubular member compressed between said nut and the injector. The lance additionally comprises the anti-rotation device which can prevent the rotation of the tubular member when the nut is screwed. 
         [0012]    The anti-rotation device is a resilient element which is deformed as soon as rotation of the nut begins, such as to be blocked between the tubular member and the inner wall of the bore, and thus prevent the rotation of the tubular member. In addition, the resilient element can be arranged between the lance and the bore. According to a first embodiment, the resilient element is a torsion spring which is wound in a cylindrical helix around the tubular member. In addition, the torsion spring comprises a lug at one end, the lug being anchored in a groove provided in the proximal bore in the intake mouth of the bore. A second embodiment is characterized in that the resilient element is a double torsion spring wound in a cylindrical helix around the tubular member. The double torsion spring comprises two lugs respectively at each end, the two lugs being anchored in the groove in the bore. The fuel lance also comprises the anti-rotation device as described in the different embodiments. In addition, an internal combustion engine comprises an injector supplied by the fuel lance as previously described in the different embodiments. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0013]    Other characteristics, objectives and advantages of the invention will become apparent from reading the following detailed description, and with reference to the appended drawings provided by way of non-limiting example, in which: 
           [0014]      FIG. 1  is a view in cross section of a known fuel lance. 
           [0015]      FIG. 2  is a view in cross section of the fuel injector lance assembly according to the invention. 
           [0016]      FIG. 3  is a view in cross section of the anti-rotation device with a torsion spring according to the invention. 
           [0017]      FIG. 4  is a view in cross section of the anti-rotation device with a double spring according to the invention. 
           [0018]      FIG. 5  is a view in cross section of the tubular member and the securing nut. 
           [0019]      FIG. 6  is a view in cross section according to the axis VI represented in  FIG. 5 . 
       
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0020]    As illustrated in  FIG. 2 , the fuel lance  100  is arranged in a long bore  102  pierced in a top engine  104  also known as a cylinder head. The fuel lance  100  extends from an intake orifice  116  to a pit  108  which is provided in order to receive a fuel injector  110 . 
         [0021]    The fuel lance  100  comprises a tubular member  118 , which is arranged in the long bore  102 , a securing nut  112  which cooperates with the tubular member  118 , and an anti-rotation device  120  fitted on the tubular member. 
         [0022]    The tubular member  118  extends along the long bore  102 , from the intake orifice  116  of the head  104  as far as an outlet orifice  122  of the head  104  which opens into the pit  108 . The tubular member  118  comprises an intake mouth  106  and an outlet mouth  124 . As illustrated in  FIG. 5 , the intake mouth  106  has an end  142  with a male spherical form, the top of which is cut off. The outlet mouth  124  has a surface with a male spherical form. The outlet mouth  124  cooperates with an intake mouth  126  of the injector  110  which has a surface with a female conical form. The tubular member  118  has a cylindrical form. The tubular member  118  comprises a proximal channel  128  in the intake orifice  116  of the head  104 , in order to receive an anti-rotation device  120 . 
         [0023]    In  FIG. 2 , the securing nut  112  is fitted on the proximal intake mouth  106  of the tubular member  118  of the intake orifice  116  of the head  104 . The nut  112  is partially on the exterior of the intake orifice  116 . As illustrated in  FIG. 5 , the securing nut  112  comprises a recess in order to receive a seal  130 . The seal  130  is designed to form a seal against fuel between the securing nut  112  and the surface of the head  104  which delimits the long bore  102 . The seal  130  is distal relative to the outlet mouth  124  of the lance  100  in contact with the injector  110 . As illustrated in  FIG. 5 , the securing nut  112  comprises a region threaded on the exterior  138 , which is designed to cooperate with the screw threads formed in the intake orifice  116  of the head  104 . In its interior, the nut  112  comprises a bore with an end  115  in the form of a distal cone of the tubular member  118 , and an end  140  in the form of a female cone. The inner end  140  of the securing nut  112  which is oriented towards the interior of the long bore  102  cooperates with the intake mouth  106  of the tubular member  118 . The cone of the inner end  140  is in axial compression against the end  142 . 
         [0024]    The anti-rotation device  120  is a resilient element which is deformed as soon as the rotation of the securing nut  112  begins. The resilient element is arranged between the lance  100  and the bore  102 . The anti-rotation device  120  is fitted around the channel  128  in the tubular member  118 , at a proximal distance from the intake mouth  106 . The anti-rotation device  120  is in contact with a groove  132  provided in the bore  102  in the head  104  of the cylinder. 
         [0025]    In a first embodiment illustrated in  FIG. 3 , the anti-rotation device  120  is a torsion spring which is wound in a cylindrical helix around the tubular member  118 . The spring  120  is in contact both with the channel  128  provided in an outer surface of the tubular member  118 , and the groove  132  provided in the bore  102 . The torsion spring  120  comprises a lug  134  at one end. As illustrated in  FIG. 6 , the lug  134  is anchored in the groove  132  in the bore  102 , which means that the lug is inserted in the groove, and can exert rotation in the groove around the main axis A. The spring  120  has two positions, i.e. a first, released position when the spring  120  is at rest, and a second, constrained position when tightening torsion torque is applied. The direction of winding of the torsion spring  120  is to the right, i.e. the helix rises to the right. The following information is provided by way of example in order to illustrate the first embodiment. The length of the fuel lance is substantially equal to 100 mm. The length of the securing nut is substantially equal to 55 mm, with a diameter substantially equal to 22 mm. The diameter of the bore  102  is substantially equal to 12 mm. The spring has a length substantially equal to 12 mm, with a number of 5 turns. The winding to the right of the spring  120  is used for screwing of the fuel lance  100 . 
         [0026]    According to a second embodiment illustrated in  FIG. 4 , the anti-rotation device  120  is a double spring wound on the tubular element  118 . The torsion spring  120  which is wound in a cylindrical helix is provided with two lugs  134 ,  136  respectively, situated at the two ends of the spring  120 . The first lug  134  is anchored in the groove  132  in the bore  102 , and the second lug  136  is anchored in the groove  132  in the bore  102 , which groove is distal relative to the first lug  134 . The two lugs  134 ,  136  are anchored, which means that they are inserted in the groove, and can turn around the main axis A. The spring  120  has two positions, i.e. a first, released position when the spring  120  is at rest, and a second, constrained position when a tightening or untightening torque is applied. The spring  120  has two opposite windings. The two windings can have either an identical number of turns or a different number of turns. Similarly, the angular rigidities of the two windings can be identical or different. The direction of one of the two windings of the spring  120  is to the right for the screwing of the fuel lance  100 , and the direction of the other winding is to the left for the unscrewing of the fuel lance  100 . The following information is provided by way of example in order to illustrate the second embodiment. The length of the fuel lance is substantially equal to 100 mm. The length of the securing nut is substantially equal to 55 mm with a diameter substantially equal to 22 mm. The diameter of the bore  102  is substantially equal to 12 mm. The double spring  120  has a length substantially equal to 23 mm with a total number of 10 turns, i.e. 5 turns in one direction of winding of the spring  120 , and 5 turns in the other direction of winding. The winding to the right of the double spring  120  is used for the screwing of the fuel lance  100 , and the winding to the left is used for the unscrewing of the fuel lance  100 . If the screwing of the fuel lance  100  is selected to be anticlockwise, then the screw pitch is to the left. Thus, the double torsion spring  120  has a first direction of winding to the left of the double spring  120  for the screwing, and a second direction of winding to the right of the double spring  120  for the unscrewing of the fuel lance  100 . 
         [0027]    In the first embodiment, during the screwing of the nut  112 , the torsion spring  120  turns around its main axis A in the direction of screwing, until contact takes place between the lug  134  and the groove  132  in the bore  102  in the head  104 . The spring  120  is tightened around the tubular element  118  during the rotation of the nut  112 , whilst being compressed until the rotation of the tubular element  118  is blocked. When the screwing is stopped, the spring  120  remains tightened on the tubular member  118 , and the lug  134  remains in contact with the groove  132 . 
         [0028]    In the second embodiment, when the nut  112  is screwed, the double torsion spring  120  begins the rotation around its main axis A until contact takes place between the lug  134  and the groove  132  in the bore  102  in the head  104 . The spring  120  is tightened around the tubular element  118  with one of the turn windings during the rotation of the nut  112 , whilst being compressed, and the spring  120  blocks the rotation of the tubular element  118 . When the screwing is stopped, the spring  120  remains tightened on the tubular element  118 , and the lug  134  remains in contact with the groove  132 . If there is unscrewing of the securing nut  112 , the torsion spring  120  is untightened from around the tubular member  118  for the winding to the right, whereas the winding to the left progressively tightens on the tubular member  118  by means of the contact between the lug  136  and the groove  132  in the bore  102  in the head  104 , until the rotation of the tubular member  118  is blocked. Thus, the nut  112  can be untightened without rotation of the tubular member  118 , and the generation of undesirable particles will also be avoided during the untightening. 
         [0029]    In order to assemble the fuel lance  100 , the resilient element  120  is fitted by placing it around the tubular member  118  via the end  106  as far as the channel  128  in the tubular element  118 , which channel is proximal relative to the end  106  which receives the securing nut  112 . The resilient element  120  is fitted tightened on the tubular element  118 . The fuel lance  100  is then fitted in the bore  102  in the head  104 , the end  124  of which opens into an outlet orifice  122  cooperating with the intake mouth  126  of the injector  110  with a female cone. During the fitting of the nut  112  on the fuel lance  100 , the nut  112  is screwed into the threaded area  138  of the bore  102 . The interior end  140  of the nut  112  comes into contact with the end  142  of the intake mouth  106  of the tubular element  118 . When the securing nut  112  is screwed into the bore  102 , the fuel lance  100  begins to turn around its main axis A until the anti-rotation device  120  prevents the rotation of the tubular member  118 , when the nut  112  is screwed. The resilient element  120  is then tightened on the tubular element  118 , and blocks its rotation. The securing nut  112  then receives the fuel duct via the intake orifice  115 , which is not represented in the figures.