Patent Publication Number: US-2007122294-A1

Title: Pump

Description:
The invention relates to a pump, a tensioning element and an engine.  
      An engine is typically equipped with a cooling system which comprises a coolant pump designed to convey coolant within the cooling system. The coolant pump is driven by a chain or belt of the engine for this purpose.  
      The present invention provides a pump having the features of claim  1 , a pump having the features of claim  9 , a tensioning element having the features of claim  19  and an engine having the features of claim  21 .  
      The pump according to claim  1  of the present invention is designed for conveying coolant in an engine. Integrated in this pump is a tensioning element which is designed for tensioning a drive member of the engine.  
      Thus, a pump is provided having an integrated function for conveying coolant in a cooling system of the engine or an internal combustion engine. The drive member which is looped around a number of shafts in the engine and is also designed to drive the pump may be tensioned by the tensioning element of the pump. The tensioning element can compensate changes in length which occur during the operation of the drive member.  
      The tensioning element may be inserted in a pump housing of the pump. It is thus readily possible to equip a pump with the tensioning element as a later add-on. However, the tensioning element may also be constructed as an integral part of the pump, preferably of the pump housing.  
      Incorporating the tensioning element in the pump may be carried out for example by means of a hydro-element. If the tensioning element has been inserted in the pump housing steps are taken to supply it with pressurised oil from a main oil channel of the engine.  
      A shaft of the pump which is connected to a drive wheel, this drive wheel being rotated by the drive member, is mounted in a preferably hydrodynamic plain bearing. This plain bearing is lubricated through a first bore which is connected to the main oil channel. This first bore inside the pump housing connects the main oil channel of a cylinder crank case of the engine with a subsidiary oil channel of the pump.  
      Depending on the coolant used the pump may be constructed as a coolant pump or as a water pump. The drive member is then constructed as a component of a primary control assembly of the engine. This drive member may take the form of a chain, belt, particularly a toothed belt, V-belt or flat belt.  
      The pump preferably has a shaft mounted on the plain bearing. At one end of the shaft there is usually a drive wheel which cooperates with the drive member, so that the shaft is set in rotation by means of the drive wheel when the engine is running.  
      A closed pump wheel may additionally be integrated in the pump with the integrated tensioning element. This closed pump wheel is preferably attached to another end of the shaft, rotates with the rotating shaft and thus provides a delivery of a volume flow of the coolant needed to cool the engine.  
      The pump according to claim  9  of the invention is designed for conveying coolant in an engine. Integrated in this pump is a closed pump wheel.  
      As the pump wheel is closed, an optimum gap situation is obtained within the pump. The closed pump wheel is easy to manufacture.  
      The pump is preferably constructed as part of a cooling system of the engine. During operation of the cooling system with the pump, the coolant or a cooling liquid can flow axially over the rotating pump wheel.  
      A washer may be provided on a rear side of the pump wheel. In addition, a face seal may press this washer against the pump wheel. Thanks to this washer, which may for example be constructed as a rotary washer, the pump wheel may be produced in its finished shape without the need for any further machining.  
      Thanks to the preferred constructed of the pump wheel as a closed wheel the gap may be very easily and accurately formed by cylindrical machining in a cylinder crank case of the engine, thus obtaining a optimum gap situation in the pump. Owing to the fact that the washer on the back of the pump wheel is pressed against the pump wheel by the face seal, there is no need for a mechanical connection between the washer and the pump wheel. The use of the washer means that the closed pump wheel can easily be installed in the pump.  
      According to a further feature the shaft is mounted radially on a preferably hydrodynamic plain bearing, this plain bearing being supplied with pressurised oil by a main oil channel from a cylinder crank case of the engine. Thus, an inexpensive mounting can be provided for the shaft of the pump. This arrangement improves the fit of the closed pump wheel into the pump housing. Usually, shafts are axially sealed in pumps of this kind, which may result in problematic axial play of the shaft. This is avoided in the present pump by a radial seal for sealing off the shaft radially.  
      A drive wheel or a pump wheel of the pump can be driven by the drive member from the primary control assembly of the engine. The pump has a spiral geometry, for example, and is cast in a V-shaped space in a cylinder crank case of the engine.  
      For manufacture or assembly the pump wheel and the drive wheel may be screwed onto the shaft by means of a thread counter to a direction of rotation of the shaft when the pump is operated, either clockwise or anticlockwise, as the case may be.  
      According to a further feature an axial bearing of the shaft is provided by a flange on the plain bearing, arranged between the shaft and the drive wheel. In this case a relief bore simultaneously forms a lubricating pocket for this axial bearing on the pump wheel side. Moreover, the present pump may have a closure for a main oil bore. Furthermore, suitable distribution may be provided for a main oil current.  
      The pump may also have a pump cover, this pump cover being designed to close off a pump chamber of the pump.  
      According to one feature, the pump according to claim  9  additionally has a tensioning element integrated into it which is designed to tension the drive member of the motor.  
      The present pump may thus have at least one component cooperating with the drive member of a control assembly of the engine. This minimum of one component is constructed either as the tensioning element provided for tensioning the drive member and/or as the pump wheel driven by the drive member. High integration of component functions can be achieved with the pump according to the invention.  
      Regardless of which of these two above-mentioned components the pump comprises, it may have a leakage chamber which is separated from an oil chamber of the pump by a shaft seal.  
      This leakage chamber is preferably sealed off from the oil chamber and a water chamber by an O-ring. Furthermore, the leakage chamber may be vented to the outside by a bore or through an annular chamber between the pump housing and the cylinder crank case of the engine.  
      Should the face seal within the pump malfunction, this can be detected by the escape of coolant at the bore in the cylinder crank case provided as a vent. Accordingly, it is possible to locate a fault irrespective of whether it has been caused by a defective face seal or by a defective radial shaft seal, without taking the engine apart. Such detection is assisted by a suitable arrangement of a leakage channel inside the engine and/or pump.  
      The pump is constructed, for example, as a water pump. If the coolant used in the cooling system of the engine is a mixture of water and a coolant such as an antifreeze, for example, this pump is constructed as a coolant pump.  
      The cooling system with the pump ensures a sufficient cooling performance of the engine or of an internal combustion engine under all operating conditions.  
      The pump for conveying the coolant inside the cooling system is usually mechanically driven by a toothed or poly-V-belt or a chain as drive member. The tensioning element integrated in the pump according to the invention tensions the drive member of the engine to the extent which is suitable for the particular operational situation.  
      Thus, the drive member is sufficiently highly tensioned in all the operational situations of the engine, so that rotary movements can be effectively transmitted between the individual wheels of shafts of the engine around which the drive member is looped.  
      All in all, irrespective of any specific embodiment, a pump is provided for conveying coolant for an internal combustion engine with integrated function, this pump incorporating at least one of the following components, namely the tensioning element, the closed pump wheel and/or the leakage chamber.  
      The tensioning element according to the invention is constructed for tensioning a drive member of an engine and is integrated in a pump which is constructed for conveying coolant within this engine.  
      This tensioning element may be constructed as a chain or belt tensioner depending on the design of the drive member.  
      The engine according to the invention may comprise a drive member and the pump according to the invention, in one of the possible embodiments. Accordingly, the drive member of this engine cooperates with at least one component of the pump. This minimum of one component of the pump may be constructed as the tensioning element integrated in the pump, so that the drive member cooperates with tensioning element, and/or as the pump wheel integrated in the pump, so that the drive member cooperates with this pump wheel.  
      Further features and embodiments of the invention will become apparent from the description and the accompanying drawings.  
      It should be understood that the features mentioned above and those yet to be described can be used not only in the particular combination stated but also in other combinations or on their own, without departing from the scope of the present invention. 
    
    
      The invention is schematically illustrated by an exemplifying embodiment shown in the drawings and is hereinafter described in detail with reference to the drawings.  
       FIG. 1  shows a schematic view of an embodiment of a pump.  
       FIG. 2  shows a schematic sectional view of the pump of  FIG. 1 .  
       FIG. 3  shows a schematic view of an embodiment of an engine comprising the pump of  FIG. 2 .  
    
    
      The Figures are described together and in overlapping manner, with identical reference numerals used to denote identical components.  
       FIG. 1  shows a pump  2  or water pump in schematic view. This pump  2  has a pump housing  3  and is designed for conveying coolant in a cooling system of an engine, not shown in  FIG. 1 .  
      In the present embodiment a tensioning element  4  is integrated in the pump housing  3  of the pump  2 . This tensioning element  4  is designed to tension a drive member of the motor, not shown here. In the pump  2  illustrated by this embodiment, a closed pump wheel  6  is also integrated.  
      The pump  2  also comprises a drive wheel  8 . Once the pump  2  has been installed in the engine, it is envisaged that the drive member of the engine, which is preferably in the form of a chain or, alternatively, a belt, loops around the drive wheel  8  which is in the form of a chain wheel in the present embodiment. The drive member of the engine also loops around a number of wheels which are mounted on shafts of the engine.  
      When the engine is running, a rotary movement is transmitted through the drive member between the shafts of the engine and the pump  2 , via the drive wheel  8 . By means of the tensioning element  4  integrated in the pump  2 , and in the form of a chain tensioner in this instance, the drive member is tensioned in all the operational situations during the running of the engine, so that effective transmission of the rotary movement is possible. The pump housing  3  additionally has encircling grooves  9  to accommodate O-rings.  
       FIG. 2  shows a sectional view through the pump  2  illustrated in  FIG. 1 , along the dotted line II-II. This view shows a shaft  10  of the pump  2 . It is envisaged that the pump wheel  6  and the drive wheel  8  are screwed on this shaft  10  by means of a thread counter to a direction of rotation of the shaft  10 . When the engine is running, rotary movement of the drive wheel  8  is transmitted via the shaft  10  to the pump wheel  6 . A shaft seal  11  is arranged around the shaft  10 .  
      The closed pump wheel  6  opens into a coolant channel of the cooling system of the engine. When the engine is running, coolant contained within the cooling system flows onto the closed pump wheel  6  from the axial direction, as indicated by the double arrow. The closed pump wheel  6  causes the coolant to flow within the cooling system, so that the engine or an internal combustion engine in which the pump  2  is arranged is adequately cooled at all operating points under all operating conditions.  
      A washer  12  on the back of the closed pump wheel  6  is pressed against the closed pump wheel  6  by a face seal  14 . This does away with the need for a mechanical connection between the washer  12  and the closed pump wheel  6 . Moreover, the closed pump wheel  6  can be produced in its finished state by the mounting of the washer  12  and needs no further machining.  
      In addition, the pump housing  4  with a pump element  16  comprises a first bore  18 , a venting bore  20  and a second bore  22 .  
       FIG. 3  shows, in schematic sectional view, the pump  2  inside an engine  24  constructed as a V-engine. The pump  2  of the V-engine integrates the face seal  14  and a plain bearing  26  as well as the tensioning element  4  for a control assembly or primary control assembly of the engine  24 . When the engine is running the drive wheel  8  has a drive member (not shown here) looping around it and causing it to rotate. The tensioning element  4  integrated in the pump  2  is designed to tension this drive member.  
      The closed pump wheel  6  is driven by the drive member via the drive wheel  8  and the shaft  10 . The closed pump wheel  6  is of helical construction and is cast in a V of a cylinder crank case  25  of the engine  24 . Arranged in this cylinder crank case  25  is a water channel  27  of a cooling system for the engine  24 . During the operation of the engine  24  coolant from the water channel  27  flows axially over the closed pump wheel  6 .  
      A gap in the closed pump wheel  6  can be provided very easily and accurately by cylindrical machining in the cylinder crank case  25 .  
      The pump shaft  10  is mounted radially on the preferably hydrodynamic plain bearing  26 , which is supplied with pressurised oil by a main oil channel  28  from the cylinder crank case  25  through the second bore  22  shown in  FIG. 2 .  
      An axial bearing  30  of the pump shaft  10  is provided by a flange on the plain bearing  26 , which is arranged between the pump shaft  10  and the drive wheel  8 . The venting bore  20  from  FIG. 2  also constitutes a lubricating pocket for the axial bearing  30  on the drive wheel side.  
      The tensioning element  4  is inserted in the water pump housing  3  and is supplied with pressurised oil by the main oil channel  28  while the engine  24  is running. The plain bearing  26  is lubricated through the second bore  22  from this main oil channel  28 . The pump housing  3  simultaneously connects the main oil channel  28  to secondary oil channels.  
      The shaft seal  11  separates an oil chamber from a leakage chamber arranged behind the face seal  14  and covered by the face seal  14  in  FIG. 3 . This leakage chamber is vented to the outside through the first bore  18  via an annular chamber between the pump housing  3  and the cylinder crank case  25 . The leakage chamber is sealed off from a water chamber and the oil chamber by at least one O-ring  32 , which is arranged in one of the grooves  9  formed in  FIG. 1  or  2 .  
      In the event of malfunction of the face seal  14  or shaft seal  11 , this can be detected by the escape of coolant or oil from a relief bore  36  on the cylinder crank case  25 , i.e. it is possible to locate the fault without taking the engine apart, depending on whether the fault is on the face seal  14  or on the shaft seal  11 .