Abstract:
A valve comprises a valve body, a flap, and a shaft driving the flap. At least one first bearing guides a first end of the shaft. The first end of the shaft includes an inner housing emerging axially. The first bearing includes a barrel axially engaged in the inner housing, such that no accumulation of condensates can occur in the inner housing when the first end of the shaft points downward.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority to FR 16 51428, filed Feb. 22, 2016. 
       BACKGROUND 
       [0002]    The invention generally relates to valves for vehicle exhaust lines. 
         [0003]    More specifically, according to a first aspect, the invention relates to a valve for a vehicle exhaust line, of the type comprising: a valve body inwardly defining a passage for the exhaust gases; a flap arranged in the passage; a shaft connected to the flap and having first and second ends opposite one another; at least one first bearing connected to the valve body and arranged to guide the rotation of the first end of the shaft relative to the valve body such that the flap is rotatable relative to the valve body around a rotation axis. 
         [0004]    Such a valve is frequently arranged with the first bearing turned downward, i.e., toward the rolling surface of the vehicle. A drive motor of the flap in this case is typically placed above the valve body, and is therefore protected from projections of water or solid materials coming from the rolling surface. In the valves of the state of the art, it was observed that the first end of the shaft could deteriorate quickly. 
       SUMMARY 
       [0005]    In this context, the invention aims to propose an exhaust line valve that does not have this flaw. 
         [0006]    To that end, the invention comprises a valve where a first end of the shaft includes an inner housing opening axially, the first bearing including a barrel axially engaged in the inner housing. 
         [0007]    Thus, when the first end of the shaft points downward, no accumulation of condensates can occur in the inner housing receiving the barrel of the first bearing. 
         [0008]    Indeed, in a valve whose first bearing includes a cylindrical housing guiding the first end of the shaft, condensates can accumulate in this cylindrical housing. Such condensates may become acidic, with a pH of less than 2. If the vehicle is used only for short distances, these condensates are not evaporated. Due to their acidity, they attack the first end of the shaft and cause significant corrosion thereof. 
         [0009]    If the vehicle travels near the sea, the condensates include dissolved salt, which ultimately crystallizes. The salt crystals wear the first end of the shaft by friction. 
         [0010]    The valve according to the invention makes it possible to eliminate these problems. 
         [0011]    The valve may also have one or more of the features below, considered individually or according to any technical possible combination(s). The shape of the barrel is a cylinder of revolution around the rotation axis. The barrel is radially defined by a lateral surface having a convex shape in section in a plane including the rotation axis. The barrel is radially defined by a lateral surface having an arc-of-circle shape in section in a plane including the rotation axis. The arc of circle has a radius comprised between 30 and 150 mm. The barrel is engaged in the inner housing with a radial play comprised between 0.05 and 0.5 mm. The second end of the shaft has a shoulder. The valve includes a sealing ring slipped around the second end of the shaft and which has a radially inner surface bearing against the shoulder along a linear contact zone with a closed contour. The radially inner surface, considered in section in a plane containing the rotation axis, is convex, preferably an arc of circle or an ellipse arc. The radially inner surface has a frustoconical general shape, coaxial to the rotation axis, and forming an angle comprised between 30° and 60° with the rotation axis. The valve includes a second bearing connected to the valve body and arranged to guide the rotation of the second end of the shaft relative to the valve body, the second bearing having an orifice with a given inner diameter. The second end of the shaft is engaged in the orifice and has an outer diameter equal to the inner diameter minus a play comprised between 0.1 and 1 mm. The valve comprises a sleeve made from an elastic material that is inserted between the barrel and an inner surface of the inner housing. 
         [0012]    According to a second aspect, the invention pertains to a vehicle exhaust line equipped with a valve having the above features. 
         [0013]    According to a third aspect, the invention pertains to a vehicle including an exhaust line equipped with a valve having the above features and arranged such that the first end of the shaft points toward a rolling surface of the vehicle. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0014]    Other features and advantages of the invention will emerge from the following detailed description, provided for information and non-limitingly, in reference to the appended Figures, in which: 
           [0015]      FIG. 1  is a perspective view of a valve according to the invention; 
           [0016]      FIG. 2  is a sectional view of the valve of  FIG. 1 , in a plane containing the rotation axis of the valve; 
           [0017]      FIG. 3  is an enlarged view of the first bearing and the end part of the shaft; 
           [0018]      FIG. 4  is a simplified schematic illustration of a motor vehicle whose exhaust line is equipped with the valve of  FIG. 1 ; and 
           [0019]      FIG. 5  is a view similar to  FIG. 3 , showing an alternative embodiment of the invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0020]    The valve  1  shown in  FIG. 1  is designed to be installed inside a vehicle exhaust line. 
         [0021]    Typically, this vehicle is a motor vehicle, for example a car or truck. 
         [0022]    The valve is a two-way valve, or a three-way valve, or any other suitable type. It is, for example, of the all or nothing type, or on the contrary a proportional valve, able to be moved between a plurality of positions making it possible to modulate the exhaust gas flow rate through the valve. 
         [0023]    The valve  1  comprises a valve body  3  inwardly defining a passage  5  for the exhaust gases, a flap  7  arranged in the passage  5 , and a shaft  9  connected to the flap  7 . The shaft  9  has first and second ends  11 ,  13  opposite one another. 
         [0024]    The flap  7  is rotatable relative to the valve body  3  around a rotation axis X. The shaft  9  extends along the rotation axis X. 
         [0025]    To move the flap  7 , the valve  1  typically includes an actuator  15  arranged to rotate the shaft  9 . 
         [0026]    In the illustrated example, the valve body  3  includes two valve half-bodies  17 ,  19  rigidly fastened to one another and substantially tight against the exhaust gas. 
         [0027]    The valve half-bodies  17 ,  19  are stamped half-shells. The valve half-bodies  17 ,  19  have a concave shape, the concave sides facing one another. The half-bodies  17 ,  19  are defined by respective free edges attached against one another and fastened to one another using any suitable method, for example by welding lines. 
         [0028]    Alternatively, the valve body  3  is molded. 
         [0029]    The valve body  3  has an exhaust gas inlet  21  and outlet  23 . The passage  5  extends from the inlet  21  to the outlet  23 . In the illustrated example, the inlet  21  and the outlet  23  are each defined in part by the half-body  17  and in part by the half-body  19 . 
         [0030]    In the illustrated example, the valve  1  is integrated into a heat recovery device. 
         [0031]    To that end, the valve body  3  includes a first opening  25 , provided to allow the exhaust gases to circulate from the passage  5  toward a heat exchanger, not shown. The valve body  3  also includes a second opening  27 , allowing the exhaust gases to return from the heat exchanger and enter the passage  5 . 
         [0032]    The first and second openings  25 ,  27  are arranged on the half-body  17 , for example. 
         [0033]    A heat recovery device of this type is described in FR 2,966,873. 
         [0034]    In the example shown in  FIG. 1 , the flap  7  is movable relative to the valve body  3  between a closing position in which the flap  7  closes off a cutoff section of the passage  5 , and a freed position in which the flap  7  frees the cutoff section. The cutoff section is situated between the first and second openings  25 ,  27 . 
         [0035]    In the closing off position, the flap  7  therefore prevents the exhaust gases from circulating from the inlet  21  to the outlet  23  along the passage  5 , and therefore forces the exhaust gases to circulate inside the heat exchanger. 
         [0036]    In the freed position, the flap  7  allows the exhaust gases to circulate from the inlet  21  toward the outlet  23  along the passage  5 , without passing through the heat exchanger. 
         [0037]    For example, in the freed position, the flap  7  closes off the second opening  27 . 
         [0038]    Alternatively, the valve  1  is not associated with a heat recovery device. In this example, the valve  1  does not include the first and second openings  25 ,  27 . 
         [0039]    The shaft  9  is rigidly connected to the flap  7  and rotates the latter. In the illustrated example, the shaft  9  is rigidly fastened to one edge of the flap  7 . Alternatively, the valve  1  is of the butterfly type, and the shaft  9  is connected to the flap  7  along a line of symmetry dividing the flap  7  into two symmetrical halves. The valve  1  may be of any other appropriate type. 
         [0040]    As in particular shown in  FIGS. 2 and 3 , the valve  1  includes a first guide bearing  29  arranged to guide the rotation of the first end  11  of the shaft  9  relative to the valve body  3 . 
         [0041]    To that end, the first end  11  of the shaft  9  includes an inner housing  31  having an axially extending opening. The first bearing  29  includes a barrel  33  axially engaged in the inner housing  31 . 
         [0042]    In the illustrated example, the inner housing  31  is blind. Alternatively, the shaft  9  is hollow. In this example, the inner housing  31  would therefore extend over substantially the entire length of the shaft  9 . 
         [0043]    The inner housing  31  typically has a circular section, perpendicular to the axis X. In this case, it is coaxial to the axis X. 
         [0044]    The barrel  33 , preferably, has a cylindrical shape of revolution around the axis X. 
         [0045]    Typically, the barrel  33  is radially defined by a lateral surface  35  having a convex shape in section in a plane containing the rotation axis X. 
         [0046]    Advantageously, the lateral surface  35  has an arc-of-circle shape in section in a plane containing the rotation axis X, as illustrated in  FIGS. 2 and 3 . This arc of circle advantageously has a large radius, comprised between 30 and 150 mm. Preferably, the radius is comprised between 40 and 100 mm, and is for example equal to 50 mm. 
         [0047]    The radius is chosen based on the size of the valve  1 , in particular the length of the shaft  9 , the diameter of the shaft  9 , assembly constraints, and thermal constraints. 
         [0048]    If the radius is too small, the contact between the inner surface of the inner housing  31  and the lateral surface  35  of the barrel  33  occurs on a limited surface area, which causes pronounced wear of this contact zone. Thus, the quality of the guiding of the first end  11  of the shaft  9  may be rapidly deteriorated in this case. 
         [0049]    On the contrary, if the radius is too large, the shape of the barrel  33  prevents any misalignment between the shaft  9  and the first bearing  29 . Such a misalignment may result from a welding operation of the first bearing  29  on the valve body  3 , or from geometric flaws in the parts of the system. The misalignment may also be due to the deformation of the valve body  3  at high temperatures, or may result from the splashing of the valve body  3  when the vehicle goes through a puddle. Indeed, when the first bearing  29  is turned toward the rolling surface, the zone of the valve body  3  supporting the first bearing  29  is splashed when the vehicle goes through a puddle, while the opposite zone of the valve body  3  is protected. The zone of the valve body  3  supporting the first bearing  29  is cooled abruptly, while the opposite zone retains its initial temperature. This causes a deformation of the valve body  3 , which may create a misalignment between the shaft  9  and the first bearing  29 . 
         [0050]    Choosing the radius between 30 and 150 mm makes it possible to have a contact zone between the barrel  33  and the inner surface of the inner housing  31  with a large surface area. Initially, the contact zone between the lateral surface  35  and the inner surface of the inner housing  31  substantially corresponds to a circle and is linear. However, this contact zone quickly becomes larger due to the wear and deformation of the barrel  33 . The contact zone thus quickly has a large surface area, such that the wear of this zone is not very pronounced. 
         [0051]    The barrel  33  is generally roll-shaped. More specifically, the barrel  33  has, perpendicular to the rotation axis X, a maximum straight section situated substantially mid-height relative to the barrel  33 . The height here is considered along the axis X. The maximum section S is embodied in  FIG. 3 . The straight section decreases from the section S, following the barrel  33  axially toward the center of the passage  5  and following the barrel  33  axially toward the valve body  3 . 
         [0052]    The barrel  33  is engaged in the inner housing  31  with a radial play comprised between 0.05 and 0.5 mm, preferably comprised between 0.07 and 0.3 mm, and for example equal to 0.1 mm. 
         [0053]    The radial play corresponds to the difference between the outer radius of the barrel  33  and the inner radius of the inner housing  31 , considered at the maximum section S. 
         [0054]    If the radial play is too small, jamming of the shaft  9  may occur at high temperatures, due to the differential expansion between the shaft  9  and the first bearing  29 . Indeed, the shaft  9  is in thermal contact with the exhaust gases over substantially its entire length, while the first bearing  29  is fastened on the valve body  3 , which is relatively colder than the shaft  9  due to the fact that the valve body  3  is in contact with the atmosphere by its outer side. 
         [0055]    On the contrary, if the radial play is too great, the guiding of the first end  11  of the shaft  9  is ensured imprecisely, and vibrations may occur generating noise and wear. 
         [0056]    As shown in  FIGS. 2 and 3 , the first bearing  29  includes a base  37  engaged in a hole  39  of the valve body  3 . The base  37  sealably closes off the hole  39 . The barrel  33  extends axially from the base  37  toward the center of the valve body  3 . 
         [0057]    The valve  1  also includes a second bearing  41  connected to the valve body  3 , arranged to guide the rotation of the second end  13  of the shaft  9  relative to the valve body  3 . 
         [0058]    In the example illustrated in  FIG. 2 , the second bearing  41  includes a cylindrical part  43  engaged in a hole  45  of the valve body  3 . The second bearing  41  has an orifice  47  in which the second end  13  of the shaft  9  is engaged. This orifice  47  is defined by the cylindrical part  43 . The second bearing  41  also includes a protruding collar  49 , protruding radially outward from the cylindrical part  43 . The collar  49  is tightly welded on an outer surface of the valve body  3 , around the hole  45 . 
         [0059]    The second bearing  41  bears a cylindrical rib  53  on an end surface  51  substantially perpendicular to the axis X. 
         [0060]    The second end  13  of the shaft  9  has a terminal portion  54  that protrudes past the rib  53 . The actuator  15  includes a lever  55 , rigidly fastened to the terminal portion  54 . The lever  55  is provided to be connected to a motor, via a kinematic chain, not shown. 
         [0061]    The valve  1  also includes a compression spring  57  inserted axially between the lever  55  and the end surface  51 . In the illustrated example, the compression spring  57  is a helical spring wound around the second end  13  of the shaft  9 , the spring  57  bearing on one side on the end surface  51  and on the other side on the lever  55 . The rib  53  surrounds the spring  57 . 
         [0062]    The valve  1  also includes a sealing ring  59  slipped around the second end  13  of the shaft  9 . The sealing ring  59  has a radially inner surface  61  bearing against a shoulder  63  arranged on the first end of the shaft  9 . 
         [0063]    The radially inner surface  61  bears against the shoulder  63  along a linear contact zone with a closed contour. 
         [0064]    More specifically, the sealing ring  59  is inserted between the shoulder  63  and the second bearing  41 . The sealing ring  59  bears on the lower end of the cylindrical part  43 , situated inside the valve body  3 . The sealing ring  59  and the second bearing  41  bear against one another by respective annular surfaces, substantially perpendicular to the rotation axis X. 
         [0065]    The shoulder  63  corresponds to a transition in the shaft  9 , the diameter of the shaft  9  becoming smaller from a central segment  65  of the shaft, bearing the flaps  7 , toward the second end  13 . In other words, the diameter of the second end  13  is smaller than the diameter of the central segment  65  of the shaft  9 . 
         [0066]    The shoulder  63  has a frustoconical general shape, coaxial to the rotation axis X. The shoulder  63  forms an angle with the rotation axis X comprised between 30 and 60°, for example equal to 45°. 
         [0067]    The radially inner surface  61  of the sealing ring  59  also has a frustoconical general shape, with a diameter that becomes smaller from a lower axial end of the sealing ring  59 , turned toward the center of the passage  5 , toward an upper axial end of the sealing ring  59 , in contact with the bearing  41 . 
         [0068]    The cone trunk forms an angle with the rotation axis X substantially identical to that of the shoulder  63 . This angle is thus comprised between 30 and 60°, and is preferably equal to 45°. 
         [0069]    The radially inner surface  61  of the sealing ring  59 , with a generally frustoconical shape, extends by a cylindrical inner surface  67 , with the same diameter as the orifice  47  of the second bearing  41 . 
         [0070]    The radially inner surface  61  is not strictly frustoconical and, considered in section in a plane containing the rotation axis X, is preferably convex. Advantageously, the radially inner surface  61 , considered in section in a plane containing the rotation axis X, is an arc of circle or an ellipse arc. Thus, the bearing between the shaft  9  and the sealing ring  59  is linear, even if the shaft  9  is not strictly perpendicular to the ring  59 . Such an arrangement allows the shaft  9  to rotate relative to the second bearing  41 , in case of misalignment between the shaft  9  and the second bearing  41 . 
         [0071]    The diameter of the arc of circle is, for example, comprised between 6 and 10 mm, and is for example equal to 8 mm. 
         [0072]    Furthermore, the orifice  47  of the second bearing  41  has a given inner diameter. The second end  13  of the shaft  9  has an outer diameter equal to said inner diameter minus a play comprised between 0.1 and 1 mm. This play is, preferably, comprised between 0.2 and 0.6 mm, and is for example equal to 0.3 mm. Such play allows a misalignment of the shaft  9  relative to the first bearing  41  in case of deformation of the valve body  3 . This deformation may come from the welding of the first bearing  41  on the valve body  3 , or be related to the heating of the valve  1  due to the circulation of the exhaust gases, or be related to the differential expansion between two opposite zones of the valve body  3  due to the spraying of the zone of the valve body  3  turned toward the rolling surface. The sealing of the valve  1  is obtained on the one hand owing to the linear bearing between the sealing ring  59  and the shoulder  63  of the shaft, and on the other hand owing to the planar bearing of the sealing ring  59  on the second bearing  41 . 
         [0073]    Due to the compression force exerted by the spring  57 , the shaft  9  and the lever  55  are axially stressed toward the outside of the valve body  3 . This results in stressing the sealing ring  59  against the first bearing  41 . Likewise, the shoulder  63  of the shaft  9  is stressed against the radially inner surface  61  of the sealing ring  59 . 
         [0074]    The force exerted by the spring  57  on the shaft  9  is about 30 Newton. 
         [0075]    The shaft  9  is in a way suspended from the second bearing  41 , the first bearing  29  serving only for rotational guiding. There is normally no force along the axial direction between the shaft  9  and the first bearing  29 . The first bearing  29  only limits the travel of the first end  11  of the shaft  9  and sees to its rotational guiding. 
         [0076]    The sealing ring  59  is, for example, made from silicon nitride (Si3N4), a zirconium-based material (SrO2), silicon carbide (SC), or alumina (Al2O3). The first and second bearings  29 ,  41  and the shaft  9  are made from steel. 
         [0077]    As shown in  FIG. 1 , the first and second bearings  29 ,  41  are rigidly fastened to the same half-body, which is the half-body  17  in the illustrated example. This makes it possible to decrease the alignment and parallelism allowances. 
         [0078]    As shown in  FIG. 4 , the valve  1  is provided to be arranged in an exhaust line  69  of a motor vehicle  71 . 
         [0079]    Preferably, the shaft  9  is mounted with an orientation substantially perpendicular to the rolling plane of the vehicle  71 . The first bearing  29  is placed toward the rolling plane of the vehicle  71 , while the second bearing  41  is placed facing the other way. 
         [0080]    The inlet  21  of the valve body  3  is connected to an exhaust collector  73  capturing the exhaust gases leaving the combustion chambers of the vehicle&#39;s engine. The outlet  23  is fluidly connected to a cannula  75  making it possible to release the exhaust gases into the atmosphere. 
         [0081]    An alternative embodiment of the invention is illustrated in  FIG. 5 . Only the points by which this alternative differs from that of  FIGS. 1 to 3  will be outlined below. Identical elements, or elements performing the same function, will be designated using the same references in both alternatives. 
         [0082]    As shown in  FIG. 5 , the valve  1  comprises a sleeve  77  made from an elastic material, inserted between the barrel  33  and an inner surface  79  of the inner housing  31 . 
         [0083]    The sleeve  77  has a cylindrical shape, coaxial with the axis X. The sleeve  77  is placed around the barrel  33 . More specifically, it is radially inserted between an outer surface  81  of the barrel  33  and the inner surface  79 . 
         [0084]    The sleeve  77  is pressed against both the outer surface  81  and the inner surface  79 . 
         [0085]    The sleeve  77  is provided to allow the guiding of the first end  11  of the shaft  9 , without preventing a misalignment from existing between the shaft  9  and the bearing  29 . 
         [0086]    When such a misalignment exists, for example when the shaft  9  rotates at its second end  13  and adopts an inclined orientation relative to the barrel  33 , certain zones of the sleeve  77  are compressed, and the pressure exerted on other zones is decreased. 
         [0087]    The sleeve  77  is, for example, made from a metal knit, preferably made with one or several stainless steel wires. 
         [0088]    The wire(s) are typically made from austenitic steel or Inconel. For good compressive strength, the density of the knit must be at least 50%, and may reach 70%. 
         [0089]    In the example of  FIG. 5 , the lateral surface  35  of the barrel is not convex. It is substantially cylindrical. 
         [0090]    According to an alternative embodiment that is not shown, the roll-shaped barrel  33  extends axially toward the inside of the valve body  3  by a pin with a reduced diameter relative to the barrel. The lateral surface  35  of the barrel  33  has a convex section. An elastic sleeve, of the type described above in reference to  FIG. 5 , is slipped around the pin. It is compressed radially between the outer surface of the pin and the inner surface of the inner housing. This sleeve makes it possible to avoid vibrations and prevent the shaft from striking the barrel sharply. 
         [0091]    Although an embodiment of this invention has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of this disclosure. For that reason, the following claims should be studied to determine the true scope and content of this disclosure.