Abstract:
The invention concerns a dual surge tank for use in a cooling system of a vehicle. The dual surge tank includes a housing having an outer wall defining a container, and a divider, located within the housing, dividing the container into a first chamber adapted to contain a first liquid and a second chamber adapted to contain a second liquid, with the divider sealing the first chamber from the second chamber. The divider may provide heat insulation between the two chambers. The first chamber may contain engine coolant and the second chamber may contain electronics coolant.

Description:
BACKGROUND OF INVENTION  
       [0001]     The present invention relates generally to a cooling system for a vehicle, and in particular to a surge tank employable with vehicle cooling systems.  
         [0002]     Conventional vehicles powered by internal combustion engines typically have an engine cooling system that uses a liquid (usually a mixture of water and antifreeze) to maintain the engine within a desired range of operating temperatures. The conventional cooling systems include a radiator for cooling the liquid and a water pump for moving the liquid through the engine and back to the radiator. These cooling systems also typically employ a surge tank (also called a reservoir or an expansion tank) that operates in conjunction with the radiator. The surge tank provides a container for retaining overflow of the engine coolant due to expansion of the coolant as it heats up, and allowing engine coolant to return when coolant in the radiator cools. This is accomplished by allowing positive and vacuum pressures to move coolant between the surge tank and radiator, thus keeping the cooling system properly filled at all times.  
         [0003]     Newer types of vehicles, such as hybrid electric vehicles, may also employ an internal combustion engine—including a generally conventional liquid cooling system. Hybrid vehicles may also employ an electronic drive system. These drive systems employ high-powered electrical devices, for example, traction power inverters. Such high-powered electrical devices may need a liquid cooling system to cool the electronics. However, the preferred operating temperature for the electronics is likely to be much lower than for the engine, thus the temperature of the electronics coolant will be less than for the engine coolant. To operate under these different temperatures, the electronics coolant flows through a separate portion of the overall cooling system. This portion of the cooling system, then, will also need a surge tank for retaining overflow of electronics coolant. For this type of hybrid vehicle, a separate surge tank for electronics coolant has been located in the vehicle and connected to the electronics cooling portion of the cooling system.  
         [0004]     For such vehicles, the packaging space used and mounting structure needed to mount two surge tanks is more than is desired—especially in a hybrid vehicle where both an internal combustion engine and the electronics for the electric drive portion of the system must be packaged in the vehicle. Moreover, the cost to fabricate and assemble two separate surge tanks, as well as the assembly time needed to mount both in the vehicle, is more than is desirable.  
       SUMMARY OF INVENTION  
       [0005]     An embodiment of the present invention contemplates a dual surge tank for use in a cooling system of a vehicle. The dual surge tank includes a housing having an outer wall defining a container, and a divider, located within the housing, dividing the container into a first chamber adapted to contain a first liquid and a second chamber adapted to contain a second liquid, wherein the divider seals the first chamber from the second chamber. A first filler opening extends through the outer wall into the first chamber, and a second filler opening extends through the outer wall into the second chamber.  
         [0006]     An embodiment according to the present invention may also contemplate a dual surge tank for use in a cooling system of a vehicle. The dual surge tank includes a housing having an outer wall defining a container, and a divider, located within the housing, dividing the container into a first chamber adapted to contain a first liquid and a second chamber adapted to contain a second liquid, wherein the divider seals and is a heat insulator between the first chamber and the second chamber. A first inlet port and a first outlet port each extend through the outer wall into the first chamber, and a second inlet port and a second outlet port each extend through the outer wall into the second chamber.  
         [0007]     An embodiment according to the present invention may also contemplate a cooling system for use in a hybrid vehicle including a radiator having an overflow outlet, and a water pump having an inlet. The cooling system may also have a dual surge tank including a housing having an outer wall defining a container; a divider, located within the housing, dividing the container into a first chamber adapted to contain a first liquid and a second chamber adapted to contain a second liquid, wherein the divider seals between the first chamber and the second chamber; a first inlet port extending through the outer wall into the first chamber and in fluid communication with the overflow outlet of the radiator; a first outlet port extending through the outer wall into the first chamber and in fluid communication with the inlet of the water pump; a second inlet port extending through the outer wall into the second chamber and adapted to allow inflow of the second liquid into the second chamber; and a second outlet port extending through the outer wall into the second chamber and adapted to allow outflow of the second liquid from the second chamber.  
         [0008]     An advantage of an embodiment of the present invention is that the dual surge tank improves vehicle packaging since package space and mounting hardware are only needed for one surge tank, rather than two, for vehicles that employ separate coolants for different portions of a cooling system. This may be particularly advantageous for hybrid vehicles that have engine coolant used with an internal combustion engine and electronics coolant used with the electronics of an electric drive system.  
         [0009]     Another advantage of an embodiment of the present invention is that the overall costs are reduced. Only one set of tooling and one assembly step are required to provide the surge tank functions for two separate portions of a vehicle cooling system.  
         [0010]     An additional advantage of an embodiment of the present invention is that the heat from the higher temperature engine coolant in the dual surge tank may be insulated from the lower temperature electronics coolant in the surge tank. Thus, one container provides the surge functions needed for both portions of the cooling system, while still allowing both portions of the cooling system to operate at different temperatures. 
     
    
     BRIEF DESCRIPTION OF DRAWINGS  
       [0011]      FIG. 1  is a perspective view of a portion of a vehicle cooling system in accordance with the present invention.  
         [0012]      FIG. 2  is a perspective view of a portion of a vehicle cooling system in accordance with the present invention.  
         [0013]      FIG. 3  is a perspective view of a dual surge tank in accordance with the present invention.  
         [0014]      FIG. 4  is a perspective view of a dual surge tank in accordance with the present invention.  
         [0015]      FIG. 5  is a perspective view of a lower half of a dual surge tank in accordance with the present invention.  
         [0016]      FIG. 6  is a perspective view of an upper half of a dual surge tank in accordance with the present invention.  
     
    
     DETAILED DESCRIPTION  
       [0017]      FIGS. 1-6  illustrate a cooling system for a vehicle, indicated generally at  10 , that employs a dual surge tank  12 . The cooling system  10  includes a radiator  14 , with a coolant inlet  16 , a coolant outlet  18 , and an overflow port  20 . Mounted adjacent to the radiator  14  is a fan shroud  22  enclosing a pair of cooling fans  24 . A water pump assembly  26  for engine coolant, having an inlet  28 , is preferably driven by an internal combustion engine (not shown).  
         [0018]     The dual surge tank  12  is composed of a housing  34  having an outer wall  36  that defines a generally hollow container  38 . The housing  34  may be formed of a clamshell shaped lower portion  40  and a clamshell shaped upper portion  42 . The housing  34  may be made of, for example, a polycarbonate—although other suitable materials may be used instead, if so desired. A fluid level line  44  (shown in  FIGS. 1 and 3 ) may be molded into or marked on the outside of the dual surge tank  12 . A second fluid level line (not shown) may also be employed to indicate a desired level for the other chamber (discussed below), if so desired.  
         [0019]     Preferably, the dual surge tank  12  mounts on the fan shroud  22 . Accordingly, a pair of upper mounting flanges  46  extend from the outer wall  36  and mount on top of the fan shroud  22 . The flanges  46  may be secured to the shroud  22  with fasteners  47  or any other suitable means desired. A lower mounting flange  48  extends below the outer wall  36  and may mount to a bracket  50  extending from and mounted to the fan shroud  22 . Alternatively, the bracket  50  may be integral with the fan shroud  22  or surge tank  12 , if so desired.  
         [0020]     The dual surge tank  12  includes a divider  52 , which extends across the container  38  to define a first chamber  54  and a second chamber  56 . The divider  52  also preferably provides some heat insulation between the first chamber  54  and the second chamber  56 . This heat insulating may be effected by the divider  52  having a first divider wall  58  spaced from a second divider wall  60  to form an air gap  62  between the two. Then, if the first chamber  54  holds engine coolant, which has a relatively high operating temperature, and the second chamber  56  holds coolant for electronics, which has a lower operating temperature, the divider  52  will minimize the heat transfer from the engine coolant to the electronics coolant. Also, the divider  52  does not necessarily divide the container  38  into equal halves. For example, the first chamber  54  for holding the engine coolant may be about four times the volume of the second chamber  56 .  
         [0021]     Internal walls  64  may extend within each chamber  54 ,  56  of the container  38 . The interior walls  64  may each have one or more holes  65  of various shapes and sizes, as desired, in order to allow fluid to flow through the chambers  54 ,  56  to corresponding outlet ports (discussed below). Also, billows  66  (not shown in  FIGS. 1 and 2 ) may extend around portions of the outer wall  36  and coincide with the interior walls  64  to improve manufacturability and strength.  
         [0022]     A first filler opening  70  extends from the first chamber  54  through the top of the outer wall  36 , and a second filler opening  72  extends from the second chamber  56  through the top of the outer wall  36 . The first filler opening  70  includes a first overflow port  74  extending from the first filler opening  70 . A first pressure cap  78  (shown in  FIGS. 1 and 2 ) mounts on top of the first filler opening  70  adjacent to the first overflow port  74 . The first pressure cap  78  preferably operates similar to conventional radiator caps, with an internal mechanism (not shown) that blocks flow into the first overflow port  74  unless the pressure exceeds a first predetermined pressure, at which point the mechanism will release to allow flow through the first overflow port  74 . The second filler opening  72  includes a second overflow port  76  extending from the second filler opening  72 . A second pressure cap  80  (shown in  FIGS. 1 and 2 ) mounts on top of the second filler opening  72  adjacent to the second overflow port  76 . The second pressure cap  80  operates similar to the first pressure cap  78 , but releasing flow to the second overflow port  76  at a second predetermined pressure. Since the engine coolant and electronics coolant operate in different portions of the cooling system  10  and at different operating temperatures, it is likely that the first predetermined pressure will be different than the second predetermined pressure. As an alternative, internal overflow ports (not shown) may be employed with one or both chambers  54 ,  56  of the tank  12  instead of the first and second overflow ports  74 ,  76 .  
         [0023]     The dual surge tank  12  may also include a first sensor port  82  extending from the outer wall  36  into the first chamber  54  and a second sensor port  84  extending from the outer wall  36  into the second chamber  56 . The sensor ports  82 ,  84  allow for the mounting of sensors (not shown) to sense a condition related to the coolants within each of the chambers  54 ,  56 , if so desired.  
         [0024]     The first chamber  54  includes a first inlet port  86  and a first outlet port  88  extending therefrom. The first inlet port  86  connects to a radiator overflow hose  90  at a first end, with a second end of the radiator overflow hose  90  connected to the overflow port  20  of the radiator  14 . The first outlet port  88  connects to an outlet hose  92  at a first end, with a second end of the outlet hose  92  in fluid communication with the inlet  28  to the water pump assembly  26 .  
         [0025]     The second chamber  56  includes a second inlet port  94  and a second outlet port  96  extending therefrom. The second inlet port  94  may be connected to a hose (not shown) that is in fluid communication with, for example, a traction power inverter (not shown). The second outlet port  96  may be connected to a hose (not shown) that is in fluid communication with, for example, a low temperature electronic water pump (not shown) or electronic coolant pipe assembly (not shown).  
         [0026]     In short, the engine coolant portion of the cooling system  10  is employed to cool engine components similar to a conventional vehicle, and the electronics coolant portion of the cooling system  10  is employed to cool particular electronic components employed, for example, in a hybrid vehicle. The dual surge tank  12 , then, provides the functionality of separate surge tanks, while reducing the cost and packaging requirements associated therewith.  
         [0027]     While certain embodiments of the present invention have been described in detail, those familiar with the art to which this invention relates will recognize various alternative designs and embodiments for practicing the invention as defined by the following claims.