Patent Publication Number: US-2007113811-A1

Title: Oil chamber sealing unit of a hydraulic camshaft adjuster of an internal combustion engine

Description:
This is a Continuation-In-Part Application of pending International patent application PCT/EP2005/005372 filed May 18, 2005 and claiming the priority of German patent application 10 2004 025 246.7 filed May 22, 2004. 
    
    
     BACKGROUND OF THE INVENTION  
      The invention relates to an oil chamber sealing unit of a hydraulic camshaft adjuster of an internal combustion engine, comprising a seal member with an outer sealing face and an inner cavity including a spring element biasing the seal member toward the seal surface.  
      A hydraulic swing-wing adjuster serves for adjusting the phase position of a camshaft in relation to a crankshaft of an internal combustion engine. In this case, a pressure oil chamber is arranged between an outer wheel connected for rotation with the crankshaft and on each of the two sides of each of a number of wings of a wing wheel rotatably disposed in the outer wheel. By the pressure oil chambers being acted upon by hydraulic oil, a phase position of the camshaft can be continuously adjusted by the admission of hydraulic fluid to, or its release from, the chambers formed at opposite sides of the wings of the wing wheel which is connected for rotation with the camshaft.  
      To seal off the oil pressure chambers relative to one another, U.S. Pat. No. 6,484,678 B2 discloses oil chamber sealing units which comprise a seal member with a spring element formed separately from the seal member. The oil chamber sealing units are arranged in each case in a groove of the outer wheel or of the wing wheel and are pressed by the spring element with their sealing face against corresponding sealing faces of the wing wheel or of the outer wheel.  
      It is the object of the present invention to provide an oil chamber sealing unit which can be manufactured and assembled in a particularly simple way.  
     SUMMARY OF THE INVENTION  
      In an oil chamber sealing unit of a swing-wing camshaft adjuster of an internal combustion engine, comprising a seal member with an outer sealing surface and with an inner cavity partly surrounded by a wall, and also a separate spring element which is arranged partially in the inner cavity so as to project beyond the wall opposite the sealing surface thereof, the spring element is held in the seal body by means of a holding element extending from the seal member which consists of a deformable metal sheet.  
      Since the sealing member is formed from a deformable metal sheet, cutting operations in the production of the seal member can be reduced or entirely avoided, and a highly cost-effective production of the sealing unit can be achieved. When a smooth deformable metal sheet is used, a re-machining of the outer sealing face is not necessary. In contrast to a workpiece machined by cutting, in a rolled deformable metal sheet, the material fibers extend without interruption, with the result that the wall of the seal member can be kept very thin, while a high stability of the sealing member is obtained. A particularly lightweight seal member can thereby be achieved. A further advantage is afforded by the use of an easily weldable deformable metal sheet which is suitable for a connection to further metallic elements.  
      The material thickness of the deformable metal sheet of the seal member is adapted to the necessary rigidity of the sealing member and is expediently different from the material thickness of the spring element. Thus, the spring element is produced, for example, from a spring steel and the seal member from a metal more easily adaptable to the component contour or else with a higher material thickness for higher rigidity. Since the seal member is a component separate from the spring element, large radial gaps between the outer wheel and the wing wheel can be sealed off, while component stresses are controllable. This allows a high-tolerance, and therefore cost-effective, production of parts of the swing wing adjuster. Production of the seal member and a captive accommodation of the spring element in the seal member can be achieved in one operation by means of a progressive tool having a stamping, bending and, if appropriate, welding, soldering or adhesive bonding capability.  
      The seal member expediently consists of a sheet metal piece formed so as to be essentially U-shaped, the sealing face being arranged on the outside of the lower outer part. The spring element lies partially in the inner cavity formed by the lower center part and the two legs and projects out of the inner cavity from the open side, opposite the sealing face, of the U-profile.  
      Oil chamber sealing units are generally delivered by the manufacturer as bulk goods. A good separation of the oil chamber sealing units by means of a separating device can be achieved when the wall comprises a wall portion which is arranged at least essentially parallel to, and opposite, the sealing face. Part of the open U-side of the seal member is thus covered by this wall portion. As a result, it can be prevented that several oil chamber sealing units are hooked together. Instead of parallelism, a wall portion may be shaped such that it covers a part region of the open side of the U-profile completely from one U-leg to the other U-leg.  
      Advantageously, the holding element is arranged on the wall portion. The spring element can thereby be arranged in the inner cavity in a particularly simple way.  
      The seal member and the spring element may be co-ordinated with one another in terms of their shape such that, for the assembly of the spring element and the seal member, the spring element is bent elastically and inserted into the inner cavity of the seal member. Alternatively, the holding element is expediently formed by a sheet metal element which, during assembly, is pivoted with respect to the spring element after partial insertion of the spring element into the inner cavity. The spring element can then be inserted into the inner cavity with only slight elastic bending or even no bending at all, the spring element cannot fall out of the seal member by a subsequent pivoting of the holding element. The spring element is held captively in the seal member by means of such a very simple and cost-effective production step.  
      In a further embodiment of the invention, the spring element has a recess for engagement of the holding element. The spring element can thereby be held captively in the seal member with a particularly accurate positioning.  
      A further advantage is achieved if the spring element comprises a planar support surface, facing away from the sealing face, for the support on a further element of the swing-wing adjuster. By means of the planar support face, a large bearing face of the spring element against the further likewise planar element can be provided. As a result, the wear, in particular the wear of the support element during a movement of the spring element relative to the support element can be kept low. This embodiment is particularly suitable for elements which are produced from a soft material, for example an aluminum alloy.  
      To reinforce the planar support face, a bead is expediently formed integrally in the support face. By such a profiling of the support face, which is advantageously oriented parallel to a longitudinal direction of the spring element, a planar orientation of the bearing face can be at least essentially maintained even when the spring element is subjected to load.  
      It is proposed, moreover, that a support surface projection, facing away from the sealing face, for bearing on a further element of the swing-wing adjuster be embossed into the spring element. By virtue of the support surface projection, a particularly small support face between the spring element and the rest of the element can be achieved, with the result that a particularly low-friction movability between the spring element and the further element is obtained. This embodiment of the invention is particularly suitable when the element is manufactured from a hard and tough material, in particular high-grade steel. The embossing may be achieved by means of a three-dimensional shaping of the support projection from a metal sheet of the spring element. It is also possible for the spring element to be incised or stamped in the region of the support face and for the support surface projection to be obtained by bending of the region.  
      In a further embodiment of the invention, the support element is a welded structure. The seal member can be kept very simple and the spring element can be connected very firmly to the seal member.  
      A particularly tilt-proof positioning of the oil chamber sealing unit in the swing-wing adjuster can be achieved when the spring element comprises a center region and two lateral outer regions, the center region being held in the inner cavity by the holding element and the outer regions projecting beyond the side walls of the seal member. Two support faces of the spring element which are spaced apart from one another, for support on the further element of the swing-wing adjuster, are obtained.  
      A simple separation of this embodiment from bulk goods is achieved when the outer regions in each case comprise an end region which projects into the inner cavity. Outer regions of a plurality of oil chamber sealing units can be prevented from being entangled.  
      The invention will become more readily apparent from the following description of the invention on the basis of the accompanying drawings: 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       FIG. 1  shows in a diagrammatic sectional illustration of a swing-wing adjuster,  
       FIG. 2  shows an oil chamber sealing unit in a perspective illustration,  
       FIG. 3  shows the oil chamber sealing unit of  FIG. 2  in a sectional illustration,  
       FIG. 4  shows the oil chamber sealing unit from  FIG. 2  in a top view,  
       FIG. 5  shows a further oil chamber sealing unit in a perspective view,  
       FIG. 6  shows the oil chamber sealing unit of  FIG. 5  in a sectional view,  
       FIG. 7  shows the oil chamber sealing unit of  FIG. 5  in a top view,  
       FIG. 8  shows a further oil chamber sealing unit in a perspective illustration,  
       FIG. 9  shows the oil chamber sealing unit of  FIG. 8  in a perspective top view,  
       FIG. 10  shows the oil chamber sealing unit of  FIG. 8  in a sectional illustration,  
       FIG. 11  shows the oil chamber sealing unit of  FIG. 8  with a modified holding element, and  
       FIG. 12  shows a sectional illustration through the holding element of  FIG. 11 .  
    
    
     DETAILED DESCRIPTION OF THE VARIOUS EMBODIMENTS  
       FIG. 1  shows a diagrammatic sectional illustration of a swing-camshaft adjuster  2  of an internal combustion engine, with an outer wheel  4  and with a wing wheel  6  disposed in the outer wheel  4 . The outer wheel  4  has an external gear structure  8 , by means of which it is connected fixedly for rotation with a crankshaft of the internal combustion engine for example by means of a control chain. The wing wheel  6  is connected fixedly in terms of rotation to a camshaft  10  of the internal combustion engine.  
      The wing wheel  6  has four wings  12  which are arranged in each case in cavities of the outer wheel  4 . These cavities form in each case a hydraulic oil chamber  14  on each of the two sides of the wings  12 . The hydraulic oil chambers  14  may in each case be acted upon with pressure by hydraulic oil independently of one another. By selectively admitting hydraulic oil to the hydraulic oil chambers  14 , the position of the wing wheel  6  in relation to the outer wheel  4  can be continuously adjusted. In each case four oil chamber sealing units  16  are arranged in the wings  12  and inside of the outer wheel  4  in grooves of the wings  12  and of the inside of the outer wheel  4  to seal off the hydraulic oil chambers  14  relative to one another.  
      Such an oil chamber sealing unit  16  is shown in a perspective illustration in  FIG. 2 . The oil chamber sealing unit  16  comprises a seal member  18  and a spring element  20 . The seal member  18  is produced from a metal sheet as a result of the deforming of the metal sheet essentially into the shape of a U-profile with a center section  22  and with two side walls  24 ,  26 . The center section  22  and the side walls  24 ,  26  are integral parts of a wall which partially surrounds an inner cavity  28 .  
      The oil chamber sealing unit  16  is shown in longitudinal section in  FIG. 3  and in a top view in  FIG. 4 . The underside of the middle piece  22  forms a sealing face  30  which, in the state in which the oil chamber sealing unit  16  is installed, in, for example, the wing wheel  6 , bears against the inner face of the outer wheel  4  of the swing-wing adjuster  2 . The sealing face  30  seals off a first hydraulic oil chamber  14  adjacent to the side element  24  relative to a second hydraulic oil chamber  14  adjacent to the side element  26 . The seal member  18  is pressed against the outer wheel  4  by the spring element  20 . For this purpose, the spring element  20  is supported in the groove of a wing  12 .  
      A wall portion  32  is integrally formed on the side wall  24  and a wall portion  34  is integrally formed on the side wall  26 , the two wall portions  32 ,  34  being arranged essentially parallel to, and opposite, the sealing face  30 . In the lateral outer regions the U-profile of the seal member  18  is closed off by the wall portions  32 ,  34 , with the result that the oil chamber sealing unit  16  is prevented from being hooked together with further units in bulk goods. The holding element  36 ,  38  configured as a sheet metal element is integrally formed on each of the two wall portions  32 ,  34 . Before the spring element  20  is inserted into the seal member  18 , the two holding elements  36 ,  38  are oriented, as illustrated by the holding element  36  in  FIGS. 2 and 3 . The spring element  20  can be inserted partially into the inner cavity  28  from above and somewhat projects, opposite the sealing face  30 , out of the inner cavity  28 . After the insertion of the spring element  20  into the seal member  18 , the holding elements  36 ,  38  are bent downward by means of a forming tool, as shown for the holding element  38 . The spring element  20  is now held captive in the seal member  18 . Alternatively, the holding elements  36 ,  38  can be formed from the outset, as shown by the holding element  38  in  FIGS. 2 and 3 , and the spring element  20 , can be inserted elastically compressed, through the passage between the holding elements  36 ,  38  and then relax in the inner cavity  28 .  
      A further embodiment of an oil chamber seal unit  40  is shown in  FIGS. 5-7 . The oil chamber seal unit  40  comprises a seal  42  produced from a deformable metal sheet in the shape of a U-profile and a spring element  44  which, like the spring element  20 , is formed from a spring steel sheet. Similarly to the seal member  18 , the seal member  42  comprises a center part  46  and side elements  48 ,  50  which partially surround an inner cavity  52 . The spring element  44  has two hole-shaped recesses  54 ,  56 , through which sheet metal elements or holding elements  62 ,  64  integrally formed in each case in the a wall portion  58 ,  60  project in the mounted state. In a similar way to what has been described with regard to the oil chamber sealing unit  16 , the holding elements  62 ,  64  are bent out of an upstanding state, as shown for the holding element  62 , into the recesses  54 ,  56  after the insertion of the spring element  44  into the seal body  42 , as shown for the holding element  64 .  FIG. 7  shows the two holding elements  62 ,  64  in a mounted bent-in state. In this state, the spring element  44  is held captively in the seal body  42  by the holding elements  62 ,  64 .  
      The spring element  44  comprises a planar support face  68  which faces away from a sealing face  66  and which is provided for bearing against, for example, the inner wall of the outer wheel  4 . This planar bearing face  68  has embossed into it a bead  70  which extends longitudinally of the spring element  44 . The bead  70  serves for stiffening the support face  68 .  
       FIGS. 8-10  show a further oil chamber sealing unit  72  with a seal member  74  and with a spring element  76 . The seal body  74  is configured as a straightforward U-profile, to the center part  78  of which the spring element  76  is welded by means of a holding element  80  in the form of a welded joint. The spring element  76  comprises a center section  82  and two outer sections  84 ,  86  which project out of an inner cavity  88 . The outer sections  84 ,  86  in each case comprise an end region  90 ,  92 . The end regions  90 ,  92  in each case project into the inner cavity  88  from outside again. The end regions  90 ,  92  prevent oil chamber sealing units  72  received as bulk goods from being entangled. At the locations furthest away from a sealing face  94 , the outer regions  84 ,  86  comprise in each case a bearing projection  96 ,  98 . The bearing projections  96 ,  98  are embossed into the spring steel sheet of the spring element  76 . The bearing projections  96 ,  98  ensure essentially linear bearing contact between, for example, the inner face of the outer wheel of the swing-wing adjuster  2  and the spring element  76 . The bearing projections  96 ,  98  are embossed into a middle region of the spring element  76 , as seen from the width of the spring element  76 , and extend only over part of the width of the spring element  76 . The dimensional stability of the spring element  76  is thereby impaired only insignificantly.  
       FIGS. 11 and 12  show a further example of an oil chamber sealing unit  100  with a seal body  102  and with a spring element  104 . The spring element  104  corresponds in its configuration to the spring element  76 , but is not connected to the seal member  102  in a materially integral way, like the spring element  76 , but, instead, with a form fit. For this purpose, the seal member  102  comprises a holding element  106  in the form of a sheet metal element, which is integrally formed onto a side wall  108  of the seal body  102  which has a U-profile. After the insertion of the spring element  104  into an inner cavity  110  of the seal member  102 , this holding element  106  is pivoted, for example by means of a bending tool, into the inner cavity  110  so as to engage the spring element  104 , whereby the spring element  104  is held captively between the holding element  106  and a center part  112  of the seal member  102 .