Abstract:
Pistons for internal combustion engines often need additional cooling to attain better performance. One method of cooling involves adding oil to an oil gallery opposite a combustion zone. Adding a standpipe prevents a preestablished quantity of oil from exiting the oil gallery. Installing the standpipe intermediate a first baffle plate and a second baffle plate improves reliability of the piston and ease of manufacturing.

Description:
[0001]    This application is a continuation-in-part of co-pending application Ser. No. 09/691,372, filed on Oct. 10, 2000. 
     
    
     
       TECHNICAL FIELD  
         [0002]    This application relates to a piston for an internal combustion engine and more specifically to a piston and method of assembling the same.  
         BACKGROUND  
         [0003]    Manufactures continually strive to increase efficiency of internal combustion engines while also decreasing the physical size of the engine. One way of improving efficiency and reducing size has been to increase temperatures and pressures in the combustion chamber while also increasing speeds of a piston reciprocating in an engine. Increased speeds, temperatures, and pressures to which the piston is subjected require improved cooling to maintain reliability and reduce wear of the piston.  
           [0004]    Many pistons currently improve cooling through injecting oil or other coolants onto an underside of a piston head where the underside of the piston head is not subjected to a combustion environment. U.S. Pat. No. 5,144,922 issued to Lites et al on Sep. 8, 1992 shows a one piece spring plate along with the underside of the piston head forming a cooling gallery. In Lites, oil jets introduce oil into the cooling gallery through a first opening. Oil may exit through a second opening generally opposite the first opening. The spring plate allows oil to enter through the first opening and exit the second opening. Some oil collects in the cooling gallery. As collected oil moves in response to reciprocating of the piston, heat from the piston transfers into the oil and reduces the temperature of the piston.  
           [0005]    U.S. Pat. No. 4,986,167 issued to Stratton et al on Jan. 22, 1991 similarly improves cooling similar to Leites by introducing oil into a cooling gallery. A standpipe allows cooling oil into the cooling gallery and acts as a dam to retain oil in the cooling gallery. The oil travels to an oil outlet opposite the standpipe. Unlike Lites, a coolant may not immediately exit the cooling gallery because the standpipe.  
           [0006]    Reliably installing the standpipe in the spring plate is critical to keeping sufficient coolant in the cooling gallery. One method of intalling the standpipe involves installing the spring plate in the piston and later installing the standpipe. This method requires a mechanical locking mechanism sufficiently robust to withstand vibration, inertia loads, and temperature loading present in a combustion chamber.  
           [0007]    The present invention is directed to overcoming one or more of the problems as set forth above.  
         SUMMARY OF THE INVENTION  
         [0008]    In one aspect of the present invention a method of assembling a piston includes connecting a baffle plate between said inner surface of a outer annular wall and an inner surface of an inner annular portion. A standpipe is positioned proximate a first end portion of the baffle plate. The standpipe is secured between the first end portion of the first baffle plate and a first end portion of a second baffle plate.  
           [0009]    In another aspect of the present invention a piston has an outer annular wall with an inner surface. An inner annular portion radially inward from the outer annular wall extends axially from a top portion and has an inner surface. A first baffle plate extends between the inner surface on the inner annular bowl and the inner surface on the outer annular wall. Also, a second baffle plate extends between the inner surface on the inner annular portion and the inner surface of the outer annular wall. A standpipe is positioned between the first baffle plate and the second baffle plate. 
       
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0010]    [0010]FIG. 1 shows a cross sectioned view of an engine having an embodiment of the present invention;  
         [0011]    [0011]FIG. 2 shows a cross section view of a piston;  
         [0012]    [0012]FIG. 3 shows section view of a standpipe in the piston;  
         [0013]    [0013]FIG. 4 shows a bottom view of the piston; and  
         [0014]    [0014]FIG. 5 shows a bottom view of the piston having an alternate embodiment of the present invention. 
     
    
     DETAILED DESCRIPTION  
       [0015]    Referring now to FIG. 1, an internal combustion engine  10  includes an engine block  12  and a cylinder head  14  rigidly secured to the block  12  using conventional fastening mechanisms such as bolts, studs, welds, or adhesives (not shown). The block  12  has a plurality of bores  16  therein defining a cylinder wall  17 , only one of which is shown. In this application a cylinder liner is be placed in the bores  16  to form the cylinder wall  17 . The engine may be any conventional design such in-line, “V”, or radial, and having any number of bores  16 .  
         [0016]    The engine  10  further includes a plurality of coolant and/or lubricant directing nozzles  20 . In this application, oil (not shown) is used as the coolant. Each nozzle  20  is connected with the block  12  in a conventional manner such as welding, threaded connections, press fits, or integral with the block  12 .  
         [0017]    A piston  22  is slidably positioned within the cylinder wall  17 . A combustion zone  27  is defined by the piston  22 , the cylinder wall  17 , and the cylinder head  14 . FIG. 2 shows the piston  22  as a generally cylindrical structure having an upper portion  24  and a pin portion  26 . In this application, the piston  22  is shown as one piece. However, the piston may be any conventional piston type including an articulated piston.  
         [0018]    The upper portion  24  is further defined by a central portion  28 , a periphery portion  30 , and an outer annular wall  32 . In this application, the central portion  28  has a combustion surface  36 . While the central portion  28  is shown as concave, the central portion may be generally flat or convex. An inner annular portion  34  extends towards the pin portion  26 . The inner annular portion  34  has an inner surface  38  facing the outer annular wall. In this application, the periphery portion  30  and central portion are integral. The outer annular wall  32  extends axially away from the periphery portion  30  towards the pin portion  26  and is generally parallel with the cylinder wall  17 . The outer annular wall  32  has an inner surface  40  and an outer surface  42 . The outer surface  42  has a sealing portion  4   e  that may be adapted to any conventional manner of providing sealing between the piston  22  and the cylinder wall  17  such as a plurality of seal rings  44 . A closed cooling gallery  45  is formed between the inner surface  38  of the inner annular portion  34  and the inner surface  40  of the outer annular wall  32 .  
         [0019]    A first baffle plate  46  is connected between a lower edge portion  48  on the inner surface  38  of the inner annular portion  34  and a lower edge portion  50  of the inner surface  40  of the outer annular wall  32 . The first baffle plate  46  has a receiving groove  52  proximate a first end portion  54 . In this application the lower edge portion  48  of the inner surface  38  forms a lip. However, the first baffle plate  46  may be connected between the lower edge portions  48  and  50  using any conventional manner such as welding, press fit, or adhesives. The first baffle plate  48  may be made of any conventional material including ceramic, metal, polymer, or any material capable of withstanding vibrations, temperatures, pressures, and chemical interactions present in areas away from the combustion zone.  
         [0020]    [0020]FIG. 3 shows a generally cylindrical standpipe  56  of a predetermined length  58 . While this application shows the standpipe  56  as funnel shaped other shapes such as conical, rectangular, and circular may be used. The standpipe  56  has a first sealing band  60  and a second sealing band  62  defining a sealing groove  64 . The sealing groove  64  is positioned in the receiving groove  52  such that a second predetermined length  66  of the standpipe  56  extends into the closed cooling gallery  45 . This application shows the standpipe  56  as ovular, but any conventional shape standpipe will work. The standpipe  56  is made of a metallic material such as formed steel, but a plastic or ceramic material may also be used.  
         [0021]    In FIG. 4, a second baffle plate  68  connects between the lower edge portions  48  and  50 . The second baffle plate  68  has a receiving groove  70  proximate a first end portion  72 . The receiving groove  70  of the second baffle plate  68  connects with the sealing groove  64  and may be made of any material capable of withstanding vibrations, temperatures, pressures, and chemical interactions present in areas away from the combustion zone. In this embodiment, the first baffle plate  46  and second baffle plate  68  abut each other about 180 degrees from the standpipe  56 . Alternatively, additional baffle plates may also be used so long as a first baffle plate  46  and second baffle plate  68  secure the standpipe  56  above the coolant supply jet  20 . Similarly the second baffle plate  68  may be attached to the inner surfaces  38  and  40  in any conventional manner such as welding, adhesive, or press fit. The second baffle plate may use any material used in the construction of the first baffle plate  46 . A closed cooling gallery  69  is formed between the inner annular portion  34 , the annular wall  32 , and the pair of baffle plates  46 ,  48 .  
         [0022]    [0022]FIG. 5 shows an alternative embodiment having a drain hole formed by a second receiving groove  74  of the first baffle plate  46 ′ and a second receiving groove  76  of the second baffle plate  68 ′ located 180 degrees from the standpipe  56 ′. In this application a drain pipe  73  connects between the second receiving grooves in generally the same fashion as the standpipe  56 .  
         [0023]    Industrial Applicability  
         [0024]    Installation of the standpipe  56  in this application is simplified and provides improved reliability. The first baffle plate  46  may be installed between the inner surface  48  of the inner annular portion  34  and lower edge  50 . The sealing groove  64  on the standpipe  56  is then inserted into the receiving groove  70  on the first baffle plate  46 . The sealing groove  64  and receiving grooves  52 ,  70  have close tolerances. However, the standpipe  56  allows movement of the first baffle plate  46 . Installing the standpipe  56  after the first baffle plate  46  reduces problems associated with clearance between the standpipe  56  and ring belt portion  50  present with a pre-installed standpipe. The second baffle plate  68  is then installed similar to the first baffle plate  46 .  
         [0025]    Once the piston  22  including the standpipe  56  is installed in the engine  10 , the standpipe  56  in the first embodiment allows coolant from the oil jet  20  to enter the closed cooling gallery  45 . The second predetermined length  66  prevents coolant from exiting the closed cooling gallery  45  through the standpipe  56  until coolant levels in the closed cooling gallery  45  exceed the second predetermined length  66 . However, generally coolant may escape from gaps between the first baffle plate  46  and second baffle plate  68  or other fits between the baffle plates  46 ,  68  and the inner surface  48  or lower edge portion  50 .  
         [0026]    In the alternate embodiment, the drain pipe  73  may further control egress of coolant from the closed cooling gallery  45 . The second receiving grooves  74 ,  76  on the first baffle plate and second baffle plate further limit leakage between first baffle plate  46  and second baffle plate  68 .  
         [0027]    Other aspects, objects, and advantages of this invention can be obtained from a study of drawings, the disclosure, and the appended claims.