Patent Publication Number: US-6216646-B1

Title: Deaeration bottle for liquid cooling systems for automotive vehicle engines

Description:
BACKGROUND OF THE INVENTION 
     Current active deaeration and degassing systems for automotive cooling systems utilize a coolant bottle having a degassing chamber through which a part of the engine cooling fluid is passed continuously for the purpose of accumulating and separating gas, i.e. air from the coolant. Such deaeration systems work best when there is a designated air space in the coolant bottle for collection of any air removed from the coolant. Such systems work with high efficiency when the coolant bottle is elevated significantly above the level of coolant in the rest of the cooling system particularly the coolant level in the engine so that any air collected is maintained in the coolant bottle. However, due to lower hood lines in modern automobiles, positioning a coolant deaeration bottle above the level of coolant in the rest of the cooling system circuit is usually impossible. When the coolant bottle is not located well above the rest of the circuit, air collected in the coolant bottle can back flow into the engine&#39;s coolant circuit after operation of the engine is terminated. Often when collected air is moved out of the coolant bottle it migrates as air bubbles to the vehicle&#39;s heater used to warm the vehicle&#39;s passenger compartment. These air bubbles may prevent desirable quantities of coolant flow through the heater core, particularly during engine idling. Decreased coolant flow through the heater core prevents the heater system from initially and rapidly warming the cabin of the vehicle. Accordingly, migration of air bubbles from the heater back to the coolant bottle requires an extended operating time of the engine including relatively great engine speeds and corresponding water pump speeds. This procedure repeats itself over and over with each engine start-up/termination cycle and has the effect of diminishing effective warming of the vehicle&#39;s interior. 
     1. Field of the Invention 
     The present invention relates to an improved liquid cooling system for an automotive internal combustion engines and heater system for a vehicle&#39;s cabin which features a multi-celled deaeration bottle with a separate cell in which the location of the inlet and exit creates a liquid level defined air trap which prevents any significant flow of air collected in the bottle back into the engine or the beater. 
     2. Prior Art 
     Prior to the present invention, various vehicle engine cooling systems have employed a wide range of components for improving vehicle engine cooling. Pressurized deaeration or degassing bottles in liquid cooling systems have been used to remove suspended air from liquid coolant to improve heat transfer efficiency. Examples of such prior system are disclosed in: U.S. Pat. No. 5,329,889 issued to D. Caldwell for “Degas Tank for Engine Cooling System”; U.S. Pat. No. 4,723,596 issued to D. Splindleboech et al for “Expansion, Deaeration and Reservoir Tank For the Liquid Cooling System of Internal Combustion Engines”; and U.S. Pat. No. 5,680,833 to G. Smith for “Combination Coolant Deaeration and Overflow Bottle”. 
     SUMMARY OF THE INVENTION 
     While prior deaeration bottles and systems are effective to degas engine coolants, they do not prevent any collected air removed from the liquid coolant from returning to the engine cooling system. Typically, such back flow of air occurs particularly after an engine is shut down, subsequently restarted, and then idled or otherwise run at a relatively low speed. The present invention concerns a new and improved deaeration assembly including a degas bottle operatively connected to the engine&#39;s cooling system which also includes a connected heater for the passenger compartment. The degas bottle can be effectively located at any position relative to the coolant level of the other cooling system components and still is effective in maintaining separation of air from liquid coolant. This prevents migration of air bubbles to the passenger compartment heater core by back flow from the bottle into the active portion of the cooling system, particularly during engine cool-down after termination of engine operation. The heater core can accordingly operate with optimized efficiency even at engine idle and low speed operation. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a pictorial view of an internal combustion engine with cooling components including an associated radiator, a passenger compartment heater assembly, and a coolant deareation and overflow assembly operatively interconnected together in a liquid coolant system. 
     FIG. 2 is an enlarged pictorial view of the coolant deaeration and overflow bottle shown in FIG. 1 with parts broken away to show internal cellular structure thereof; 
     FIG. 3 is a sectioned end view of the deaeration and overflow bottle of FIG. 2 taken generally along sight lines  3 — 3  of FIG.  2  and with a diagram added thereto; and 
     FIGS. 4 and 5 are sectioned views partially broken away taken respectively along sight lines  4 — 4  and  5 — 5  of FIG.  2 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Turning now in greater detail to the drawings, illustrated in FIG. 1 is a liquid cooling system for an internal combustion engine  10  of an automotive vehicle  12 . The engine  10  is a conventional liquid cooled engine including water jackets or compartments through which liquid coolant is pumped. These compartments are connected to a heat-dissipating radiator  14  by inlet and return hoses  16  and  18 . The engine water jacket and other components are also hydraulically connected to an occupant compartment heater assembly  20  by inlet and return hoses  22 ,  24  respectively and further to a liquid coolant deaeration (degassifier) and overflow assembly (bottle)  26  by supply and outlet hoses  28  and  30 . Liquid coolant in the cooling system is pumped by a conventional engine driven pump (internal to engine  10 ) to cause the liquid coolant to flow through the cooling system. 
     Referring now to FIG. 2, the deaeration and overflow assembly or bottle  26  is a closed, multi-part container formed from upper and lower halves preferably made of plastic material which halves are fused together at mid-section horizontal flanges  27 . The bottle  26  has a first operating section providing a degassing chamber portion  34  for the purpose of extracting gas, primarily air, from the liquid coolant which is circulated through the system. Bottle  26  also has a second operating section which acts as a liquid coolant overflow chamber portion  36  for the purpose of collecting any liquid coolant which overflows from the degassifier chamber, particularly as the liquid expands during engine warm-up. The two portions  34 ,  36  are advantageously arranged in a side by side lateral relationship and separated by a common divider wall  37 . Integral brackets  38 , best seen in FIG. 1, are provided to attach the bottle assembly  26  to vehicle support structure  39  in the engine compartment. A desirable attachment for the bottle is disclosed in the above referenced U.S. Pat. No. 5,680,833 assigned to the assignee of this invention and hereby incorporated by reference. 
     Because of vehicle design constraints, such as desirable low hood lines, the deaeration and overflow bottle assembly  26  must often be positioned at an elevation lower than the heater assembly  20  as shown schematically in FIG.  3 . The degas portion or section  34  of the bottle assembly  26  is hydraulically or fluidly connected to the overflow portion or section  36  by a connection passage provided by coolant fill neck  40 . A hose  44  runs from the filler neck  40  to an inlet fitting (not shown) into the overflow chamber  36  as more particularly disclosed by the above referenced U.S. Pat. No. 5,680,833. The coolant fill neck  40  is normally covered by a pressure cap  42  which allows flow therethrough from the interior of degas chamber  34  through hose  44  and into the overflow chamber  36  as coolant expands. Conversely, the pressure cap permits coolant flow from the overflow chamber  36 , through hose  44  and into the degas chamber  34  as coolant in the engine contracts. 
     When the engine is running, the coolant pump passes liquid coolant and any air in the engine through inlet hose  28  into the degas chamber  34 . Conversely, when the engine cools after a shut-down, liquid coolant in the engine contracts and a partial vacuum condition may be created which induces coolant flow from the degas chamber  34 , through hoses  30  and  28  and back into the engine&#39;s water jackets. 
     The degassing portion or chamber  34  is best shown in FIGS. 2-3 and is a multi-cell structure created by being divided in grid-like fashion by internal walls or partitions  50 ,  52  and  54 . Walls  50 ,  52 , and  54  intersect one another substantially at right angles to define a plurality of vertically extending hollow cells  61 ,  62 ,  63 ,  64 ,  65 , and  66 . These cells are enclosed by the outer wall of the degassing chamber portion  34  and by the internal divider wall  37 . These cells are hydraulically interconnected to one another by strategically located flow-through ports or windows  71 ,  72 ,  73 ,  74 ,  75 ,  76 , and  77  formed through the walls  50 ,  52  and  54 . Moreover, these windows are arranged to hydraulically connect the cells in series flow relationship to one another so that the flow path through the degassing chamber portion  34  creates a series of degassing steps to maximize the degassing or deaeration function of the assembly  26 . Specifically, coolant flows through the cells  61 ,  62 ,  63 ,  64 ,  65 , and  66  sequentially starting from the inlet  80  fitting connecting inlet hose  28  to the first cell  61  and ending at the outlet fitting  82  connecting the final cell  66  to the outlet hose  30 . 
     More particularly, the first cell  61  of the degassing section has inlet fitting  80  located adjacent to the top of the container&#39;s side wall where coolant enters first cell  61  from hose  28  as best shown in FIGS. 2 and 3. A strategically located lower flow-through window  71  in interior wall  50  communicates the first cell  61  with adjacent second cell  62 . The portion of wall  50  between adjacent cells  61 ,  62  has no other openings and therefore this arrangement isolates the upper portion of cell  61  and its inlet formed by fitting  80  from the other cells whenever a significant coolant volume fills first cell  61 . The second cell  62  fluidly communicates with adjacent third cell  63  by a window  72  through the upper portion of the common wall portion  52  (and through a lower window  72 ′ described in the following paragraph). The vertical elevation of window  72  is approximately at the same height as the inlet fitting  80  into cell  61 . In turn, coolant in cell  63  communicates with and can flow therefrom into adjacent fourth cell  64  through an upper window  73  (and a lower window  73 ′ described in the next paragraph). Window  73  extends through the upper portion of the common wall  50  dividing cells  63 ,  64 . Likewise, coolant in fourth cell  64  communicates with and can flow therefrom into the adjacent fifth cell  65  through a pair of windows  74  and  75  which are formed in the common portion of the wall  54  which separates cells  64 ,  65 . Again, coolant in cell  65  communicates with and can flow therefrom into the adjacent sixth cell  66  through upper and lower windows  76 ,  77  in the common portion of the wall  50  between these cells  65 ,  66 . 
     The fluid connection between first cell  61  and second cell  62  by window  71  is shown fairly clearly in FIG. 2 due to the broken out section. Likewise, the location and functionality of windows  72 ,  73 ,  74 ,  75 ,  76 , and  77  between various cells  62 ,  63 ,  64 ,  65 , and  66  is readily understood from FIGS. 2 and 3. However, additional windows in the walls  50 ,  52 , and  54  are not visible in these views and therefore reference is made to FIGS. 4 and 5 which disclose the location of additional windows as follows: a lower window  72 ′ (in FIG. 5) between cells  62 ,  63 ; and a lower window  73 ′ (in FIG. 5) between cells  63 ,  64 . 
     With the strategic locations of the various windows, a liquid surface formed air trap space, designated “T”, is created within the degassifier section  34  defined by the surface of the liquid coolant within the first cell  61 . This gas trap space T effectively prevents gas or air bubbles trapped and collected at the top of cells  62 - 66  which are lighter than the liquid coolant from flowing back into the engine cooling system and into the heater core through inlet fitting  80 . Such flow would otherwise occur on engine shut down and contraction of the liquid coolant in the engine&#39;s water jackets which creates a partial vacuum therein. Accordingly, these air bubbles are prevented from collecting in the vehicle&#39;s heater core which is typically located at a higher elevation than the engine. Due to the prevention of the collection of air bubbles in the heater, the flow of engine coolant therethrough is enhanced especially when the engine is substantially restarted. Accordingly, without a restriction to flow by air bubbles, the heater operates with optimized efficiency at all engine speeds including idle so that the vehicle cabin can be efficiently warmed. 
     While a preferred embodiment of the invention has been shown and described, another cell arrangement and flow-through window pattern of other embodiments would now be apparent to those skilled in the art. Accordingly, this invention is not to be limited to that which is shown and described but by the following claims.