Patent Publication Number: US-6708653-B2

Title: Fluid reservoir

Description:
CROSS-REFERENCE 
     This application claims the benefit of priority to U.S. Provisional Patent Application No. 60/286,723 titled “COOLANT RESERVOIR VALVE FOR ENABLING REMOVAL OF RESERVOIR WITHOUT COOLANT LOSS,” filed on Apr. 27, 2001, which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     The present invention relates to a fluid reservoir for a closed loop fluid system such as, for example, is associated with an internal combustion engine. 
     BACKGROUND 
     Closed loop coolant circulation systems are typically used in conjunction with vehicle engines to dissipate heat that builds up in and around the vehicle engine. Because the coolant expands and contracts during normal operation of the coolant circulation system, a coolant reservoir is typically provided to allow excess coolant to flow into the reservoir and allow coolant in the reservoir to flow into the circulation system when additional coolant is required to fill the circulation system. Typically, this occurs as the coolants&#39; temperature fluctuates. Specifically, as the coolant&#39;s temperature decreases, it tends to contract. The use of a coolant reservoir allows the coolant to flow therein as the temperature increases, and also allows the fluid therein to flow back into the system as the temperature decreases. 
     In order for the coolant reservoir to facilitate the flow of coolant between the coolant circulation system and the reservoir, a flow aperture connecting the reservoir to the coolant system is typically disposed at a bottom portion of the reservoir such that the system is gravity fed. Unfortunately, positioning the flow aperture at the bottom of the reservoir makes disconnection and removal of the reservoir from the circulation system difficult to accomplish without spilling at least some coolant. If the coolant circulation system is used in a vehicle having a confined space for the engine components such as a personal watercraft (PWC), the reservoir must often be disposed in a position where it must be removed in order to access the engine. When conventional reservoirs are disconnected from the coolant systems to access the engine, the flow aperture becomes exposed to the ambient environment and coolant leaks out of the reservoir unless and until the user somehow seals the flow aperture. To avoid coolant leaks, conventional coolant systems are drained before removing the coolant reservoir. However, draining the entire coolant system prior to removing the reservoir is both inconvenient and time-consuming. 
     The efficiency of coolant circulation systems depends on maximizing the amount of coolant flowing through the system. Consequently, any bubbles that develop and accumulate in the fluid path reduce the efficiency of the coolant system. To minimize the presence of such bubbles, conventional coolant systems typically have bleed tubes that connect the highest point in the coolant system, which is where bubbles accumulate, to the coolant reservoir in order to encourage the bubbles to flow out of the coolant path and through the bleed tube into the reservoir. Unfortunately, because the reservoir is itself connected to the fluid loop, it is possible for the bubbles to merely flow back into the coolant path through the flow aperture connecting the reservoir to the coolant path. The flow of bubbles back into the coolant path reduces the efficiency of the system and defeats the purpose of the bleed tube. 
     Conventional coolant reservoirs are provided with filling tubes that allow a user to add more coolant to the coolant system. Unfortunately, users may accidentally overfill the reservoir with coolant by filling the reservoir above the maximum desired coolant level or by filling the reservoir above the upper rim of the filling tube. When the reservoir is filled to the maximum desired coolant level, the expansion of the coolant during operation of the coolant system may force even more coolant into the reservoir and cause the coolant to overflow. As a result, when the reservoir is filled by a user above the maximum level, excess coolant may spill out and harm engine components or make a mess. 
     SUMMARY OF THE INVENTION 
     The present invention prevents spills and/or inconveniences from occurring when the reservoir is disconnected by providing a vehicle with a fluid system defining a fluid path through which a fluid flows. The vehicle includes a removable fluid reservoir that has a container defining a fluid receiving interior space and having a flow aperture (or opening). The reservoir is removably connected to the fluid path to allow for fluid communication between the interior space of the container and the fluid path via the flow aperture. A valve is mounted to the container at the flow aperture. 
     The valve may be a manually operable ball valve. Before removing the reservoir from the coolant system, a user need only close the valve to avoid leaks. Alternatively, the valve may be a pressure-activated valve that is mounted at the flow aperture to enable the fluid to flow from the fluid path into the interior space of the container via the flow aperture to compensate for a pressure increase within the fluid path. The pressure-activated valve substantially prevents the fluid in the interior space of the container from flowing out through the flow aperture when the container is disconnected from the fluid system. 
     The present invention substantially prevents bubbles from reentering the coolant path once the bubbles have entered the reservoir by providing a vehicle that has a fluid system defining a fluid path through which a fluid flows. The first end of a bleed tube has first and second ends operatively connected to the fluid path. A fluid reservoir has a container defining an interior space. A barrier partially separates the interior space into first and second lateral interior spaces. A bleed port operatively connects an upper portion of the second interior space to the second end of the bleed tube such that air bubbles that have accumulated in the fluid path flow through the bleed tube and port into the second lateral interior space. The barrier is constructed to discourage air bubbles in the second lateral interior space from entering the first lateral interior space. A fluid passage operatively connects lower portions of the first and second lateral interior spaces to permit a substantially bubbleless fluid in the lower portion of the second interior space to flow into the first lateral interior space. A passage between the lower portion of the first interior space and the fluid path permits the fluid in the first interior space to flow into the fluid path. 
     The present invention discourages overfilling and prevents associated spills by providing a vehicle having a fluid system defining a fluid path through which a fluid is circulated. The vehicle includes a fluid reservoir operatively connected to the fluid path. The fluid reservoir comprises a container defining a fluid receiving interior space and having a flow aperture that allows for communication between the interior space of the container and the fluid path. The reservoir has a hollow filling tube having (a) an upper end into which fluid may be added and (b) a lower end disposed within the interior space at a vertical position generally corresponding to a maximum desired fluid level. The filling tube enables air that is displaced during fluid filling to escape from the interior space to an ambient environment through the lower end until a fluid level in the interior space reaches the lower end. After the fluid level has risen above the lower end, added fluid accumulates in the fluid filling tube. An air escape passage has first and second ends, the first end of which communicates with the interior space. Because the passage has a cross-sectional area substantially smaller than a cross-sectional area of an inside of the filling tube, the escape passage enables air to gradually escape from the interior space through the escape passage and fluid accumulated in the filling tube to gradually flow into the interior space when the fluid level is above the lower end. 
     The reservoir according to the present invention may further include an overflow port at an upper portion of the fluid filling tube to prevent excess coolant from spilling out of the reservoir. An overflow tube is removably operatively connected to an external end of the overflow port to permit excess vapor and fluid in the fluid filling tube to flow through the overflow port and tube into a predetermined location such as the bottom of a hull in the case of a personal watercraft (PWC). 
     The second end of the air escape passage may communicate with a portion of the fluid filling tube intermediate the upper and lower ends thereof. Alternatively, the second end of the air escape passage may be operatively connected to the overflow port and/or tube. 
     Other objects, features, and advantages of the present invention will become apparent from the following description, the accompanying drawings, and the appended claims. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     For a better understanding of the present invention as well as other objects and further features thereof, reference is made to the following description which is to be used in conjunction with the accompanying drawings, where: 
     FIGS. 1A,  1 B,  1 C, and  1 D are front, side, back and top plan views, respectively, of a coolant reservoir according to the present invention; 
     FIG. 2 is a cross-sectional view of the coolant reservoir of FIG. 1D taken along the line  2 — 2 ; 
     FIG. 3 is a schematic diagram of a coolant circulation system according to the present invention; 
     FIG. 4 is a bottom view of a diaphragm valve according to the present invention; 
     FIG. 5 is a cross-sectional view of an alternative embodiment of the present invention; and 
     FIG. 6 is a cross-sectional view of an additional alternative embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION 
     FIGS. 1A,  1 B,  1 C, and  1 D illustrate front, side, back and top plan views, respectively, of a coolant reservoir  10  according to the present invention. FIG. 2 illustrates a cross-sectional view of the coolant reservoir  10  taken along the line  2 — 2  of FIG.  1 D. 
     The coolant reservoir  10  comprises a container that defines a coolant receiving interior space  12 . A main coolant port  14  extends downwardly from the lower end of the coolant reservoir  10  to form a flow aperture (or opening)  16  that connects to the interior space  12 . A coolant filling port  18  extends upwardly from an upper end of the reservoir  10  and defines a hollow filling; tube  20  that allows a user to fill the reservoir  10  with coolant when necessary. An overflow port  22  is disposed at an upper end of the filling tube. A bleed port  24  is also disposed at an upper end of the reservoir  10 . 
     FIG. 3 illustrates a schematic diagram of a coolant circulation system  30  according to the present invention. The illustrated coolant circulation system  30  is a closed loop system that facilitates the circulation of a coolant. The coolant circulation system  30  can be used to cool the engine components  32  of various types of vehicles. In the illustrated embodiment, the coolant system  30  is used to cool the engine components  32  of a PWC. However, the coolant system  30  would be equally applicable to other types of vehicles such as all-terrain vehicles (ATVs) and snowmobiles, among others. The coolant circulation system  30  defines a coolant path  34  that flows through the engine components  32 , a thermostat  36 , and a heat exchanger  38 . The engine components  32  may include an exhaust manifold, cylinder heads, or cylinder housing, etc. When coolant in the coolant path  34  flows through the engine components  32 , the coolant absorbs heat, thereby cooling down the engine components  32 . The heat absorbed by the coolant is subsequently dissipated in the heat exchanger  38 . The volumetric flow of the coolant through the heat exchanger  38  and the engine components may be controlled by a thermostat  36  to regulate the temperature of the engine components  32 . 
     As illustrated in FIG. 3, a connecting tube  40  is operatively connected to the coolant path  34  and removably connected to the main coolant port  14  of the coolant reservoir. When the reservoir is connected to the coolant circulation system  30 , the reservoir  10  is disposed at a higher elevation than the engine  32 . Pressure differences between the coolant path  34  and the reservoir  10  lend to force the coolant out of the reservoir  10  and into the coolant path  34  via the connecting tube  40  when the pressure in the reservoir  10  exceeds the pressure in the coolant path  34 . Conversely, coolant tends to be forced out of the coolant path  34  and into the reservoir  10  via the connecting tube  40  when the pressure in the coolant path  34  exceeds the pressure in the reservoir  10 . 
     Hereinafter, the main coolant port  14  and pressure-activated valve  50  will be described with reference to FIGS. 2,  4 , and  6 . 
     A pressure-activated valve  50  is mounted in the flow aperture  16  defined by the main coolant port  14 . The pressure-activated valve  50  is designed to allow coolant to flow from the interior space  12  of the reservoir  10  out through the main coolant port  14  only when a pressure at an interior end  14   a  of the port  14  exceeds a pressure at an exterior end  14   b  of the port  14  by a first predetermined pressure gradient (or amount). To prevent coolant from leaking out through the port  14  when the reservoir  10  is disconnected from the coolant system  30 , the first predetermined pressure gradient is preferably set such that the first predetermined pressure gradient is greater than a pressure gradient experienced when the reservoir  10  is full of coolant and the exterior end  14   b  of the main port  14  is oriented downwardly and exposed to the ambient environment, as would be the case when the reservoir  10  is being disconnected and removed. At the same time, the first predetermined pressure gradient is set low enough such that when the reservoir  10  is connected to the coolant system  30  and the pressure in the coolant system  30  is reduced (for example because of lack of coolant), the valve  50  will enable coolant in the reservoir  10  to flow through the main coolant port  14  into the coolant path  34  to maintain an adequate supply of coolant in the coolant system  30 . 
     When the main coolant port  14  is operatively connected to the coolant system  30  via the connecting tube  40 , the valve  50  also enables coolant to flow from the coolant path  34  into the interior space of the reservoir via the main coolant port  14  to compensate for a pressure increase within the coolant path  34 . When pressure builds up in the coolant system  30 , the valve  50  allows excess coolant to flow from the coolant system  30  into the reservoir  10  via the main coolant port  14 . The valve  50  opens when a pressure at the exterior end  14   b  of the main coolant port  14  exceeds the pressure inside the reservoir (i.e., at the inside end  14   a  of the port  14 ) by a second predetermined pressure gradient (or amount). The second predetermined pressure gradient may be low or even zero to easily allow coolant to flow from the coolant system  30  into the reservoir  10 . 
     The valve  50  is biased toward allowing coolant to enter the reservoir  10 . To accomplish this, the first predetermined pressure gradient is set greater than the second predetermined pressure gradient. 
     As illustrated in FIGS. 2,  4  and  6 , the pressure-activated valve  50  of this embodiment comprises a flexible diaphragm  51 . As best illustrated in FIG. 4, the diaphragm  51  includes first and second slits  52 ,  54  extending at least partially across a middle portion  56  of the diaphragm  51 . The first and second slits  52 ,  54  are preferably perpendicular to each other. When a sufficient pressure gradient is experienced across the diaphragm  51 , the slits  52 ,  54  spread apart and allow coolant to flow therethrough. It should be noted that just a single slit  52  could also be used without departing from the present invention, depending upon the pressure gradient desired. As would be appreciated by those skilled in the art, the greater the number of slits  52 ,  54 , the easier coolant will flow through the diaphragm  51 . 
     The middle portion  56  of the diaphragm  51  bulges toward the interior space  12  of the reservoir  10  when there is no pressure gradient across the diaphragm  51 . This inward bulge ensures that the diaphragm  51  is biased toward allowing coolant to flow into the reservoir  10  (the first pressure gradient is greater than the second pressure gradient). When coolant pushes outward from inside the reservoir  10  because the pressure therein (at the inside end  14   a  of the port  14 ) is greater than the pressure at the outside end  14   b  of the main coolant port  14  by less than the first pressure gradient, the slits  52 ,  54  are pushed together, keeping the diaphragm  51  closed. However, when the pressure gradient exceeds the first predetermined pressure gradient (for example when the reservoir  10  is connected to the coolant system  30  and a lack of coolant in the coolant path  34  creates a partial vacuum), the slits  52 ,  54  bend outwardly toward the exterior end  14   b  of the main coolant port  14  and allow the coolant to flow therethrough into the connecting tube  40  and the coolant path  34 . 
     While the illustrated embodiment uses a diaphragm  51  as the pressure-activated valve  50 , any other suitable pressure-activated valve that would be known to one skilled in the art could also be used without departing from the spirit of the present invention. For example, a two-way check-valve having predetermined opening pressures could be positioned in the main coolant port  14 . Alternatively, two oppositely-facing one-way check valves could be positioned in parallel relation to each other in the main coolant port  14 . 
     When the reservoir  10  is disconnected and removed from the coolant system  30 , the pressure-activated valve  50  substantially prevents coolant in the reservoir  10  from leaking out through the main coolant port  14 . This non-leak feature is particularly advantageous in vehicles in which the coolant reservoir  10  must be removed in order to gain access to components usually associated with the engine. When a conventional reservoir without the valve  50  is used, a user must drain the coolant system and reservoir before removing the reservoir in order to prevent coolant from leaking out of the reservoir through the flow aperture onto the vehicle and/or engine as soon as the reservoir is disconnected. This non-leak feature is well-suited for use in such closed-loop coolant systems as are common in snowmobiles, personal watercraft, and ATVs, where the ability to remove the reservoir without draining the entire coolant system would be most helpful. 
     FIG. 5 illustrates an alternative embodiment of the invention. Where elements of this embodiment correspond exactly to elements of the previous embodiment, identical reference numerals are used. In this embodiment, a valve  53  is mounted in the main coolant port  55  of the reservoir  57 . When a user connects the reservoir  57  to the coolant system  30 , the valve  53  can be opened to allow coolant to flow between the reservoir  57  and the coolant path  34 , as is required during normal operation of the coolant system  30 . Conversely, when the reservoir  57  is operationally connected to the coolant path  34 , the valve  53  can be closed so that the reservoir  57  can be disconnected without spilling the coolant or first draining the coolant system  30 . 
     In the embodiment illustrated in FIG. 5, the valve  53  is a manually-operated ball valve  61 . Before disconnecting the reservoir  57  from the coolant system  30 , the user closes the ball valve  61 . Conversely, after connecting the reservoir  57  to the coolant system  30 , the user opens the ball valve to allow for coolant communication between the coolant path  34  and the reservoir  57 . 
     While the illustrated valve  53  is a manually-operated ball valve  61 , any other type of valve that would be known to one skilled in the art could also be used without departing from the scope of the present invention. For example, an automatically-closing quick-disconnect valve could be used as the valve  53 . If a quick-disconnect valve is used, disconnecting the reservoir  57  from the coolant path  34  automatically closes the valve. Conversely, connecting the reservoir  57  to the coolant path  34  automatically opens the valve. 
     Hereinafter, the filling tube  20  will be described with reference to FIGS. 2 and 3. 
     The fluid filling port  18  comprises a hollow filling tube  20  that extends upwardly from an upper end of the reservoir  10 . The filling tube  20  has an upper end  20   a  into which coolant may be added. A cap (not shown) is removably connected to the upper end  20   a  to prevent coolant and/or bubbles from spilling out through the upper end  20   a  when the coolant sloshes around in the reservoir  10 . A lower end  20   b  of the filling tube  20  is disposed within the interior space  12  at a vertical position generally corresponding to a maximum desired fluid level. The maximum desired fluid level is preferably disposed at a predetermined position below the top of the interior space  12  so that a pocket of compressible gas is maintained within the coolant reservoir  10 . The maximum desired coolant level  59  for this embodiment is marked on the front of the reservoir  10  as illustrated in FIG.  1 A and generally corresponds to the vertical position of the lower end  20   b . When a user fills the reservoir  10  with coolant through the filling tube  20  and the coolant level in the reservoir  10  is below the lower end  20   b  of the filling tube  20 , displaced air inside the interior space  12  of the reservoir  10  escapes to the ambient environment through the lower end  20   b . However, when the coolant level reaches and rises above the lower end  20   b  of the filling tube  20 , displaced air can no longer escape through the lower end  20   b . Consequently, additional coolant that is poured into the upper end  20   a  of the filling tube  20  accumulates in the filling tube  20 . 
     An air escape passage  60  has a first end  60   a  that is operatively connected to the interior space  12 . A second end  60   b  of the air escape passage  60  is connected to a portion of the filling tube  20  intermediate the upper and lower ends  20   a ,  20   b  thereof. Consequently, fluid and air can flow between the interior space  12  and the intermediate portion of the filling tube  20  via the air escape passage  60 . The escape passage  60  has a cross-sectional area that is substantially smaller than a cross-sectional area of an inside of the filling tube  20 . For example, the diameter of the air escape passage  60  in the illustrated embodiment is approximately 1 mm, as compared to the 22 mm diameter of the filling tube  20 . These dimensions are illustrative only and are not meant to be limiting. As would be understood by one skilled in the art, the precise cross-sectional area of the air escape passage  60  is tuned to match the opening size and shape of the filling tube  20 . For example, the cross-sectional shape of the air escape passage  60  and filling tube  20  will affect the gas and fluid flow rates therethrough. As described in greater detail below, the object is to provide an air escape passage  60  through which air flows at a substantially slower rate than coolant may be introduced into the reservoir  10  through the filling tube  20 . 
     The escape passage  60  enables displaced air to gradually escape from the interior space through the escape passage  60  and upper end  20   a . As a result, when the coolant level is above the lower end  20   b  of the filling tube  20 , fluid accumulated in the filling tube  20  gradually flows into the interior space  12  as the displaced air gradually escapes through the escape passage  60 . 
     When a user fills the reservoir  10  with coolant, the user may not be able to keep careful track of the coolant level in the reservoir  10 . The user may therefore fill the reservoir  10  above the maximum desired coolant level  59 . When this happens, the coolant level rises above the lower end  20   b  and stops displaced air from escaping through the lower end  20   b . As a result, instead of having the coolant level gradually rise in the wide area of the main interior space  12 , the coolant level quickly rises in the relatively narrow cross-sectional space within the filling tube  20 . The coolant level in the filling tube  20  rapidly rises and indicates to the user that the maximum desired coolant level has been reached. The user thereafter stops filling the reservoir  10 , the observed coolant level in the filling tube  20  having informed the user that the maximum desired coolant level has been reached. Finally, the air escape passage  60  allows the coolant that accumulated in the filling tube  20  to flow into the interior space  12  as displaced air escapes through the air passage  60  and upper end  20   a . After filling the reservoir, the user replaces the cap. 
     Hereinafter, the overflow port  22  and tube  58  will be described with reference to FIGS. 2 and 3. The overflow port  22  is operatively connected to the filling tube  20  near but slightly below the upper end  20   a . The overflow tube  58  is removably operatively connected at one end to the external end of the overflow port  22 . The opposite end of the overflow tube  58  is disposed in an area where spilled coolant will do little or no harm. For example, in a PWC, the free end of the overflow tube  58  may be disposed at a bottom of the hull of the PWC (e.g., a bilge area) away from the other components of the PWC. 
     As noted above with respect to the filling tube  20 , the coolant level in the filling tube  20  can rise quickly up to the upper end  20   a . As discussed above, the reservoir  10  in a PWC may be disposed above the engine or other vital component(s). In such a case, it is advantageous to prevent excess coolant from spilling out of the reservoir  10  at the upper end  20   a . The overflow port  22  and tube  58  prevent just such a spill. When the coolant level rises in the filling tube  20  to the level of the overflow port  22  while the user is filling the reservoir and the cap is removed, excess coolant flows through the overflow port  22 , which is disposed below the top rim of the upper end  20   a  of the filling tube  20 , instead of out of the upper end  20   a . The excess coolant flows through the overflow tube  58  and is discharged in a location where damage and mess is minimized. In the case of a PWC, the external end of the overflow tube  58  is disposed at a bottom of the hull (e.g., in the bilge area). 
     The cap (not shown) is preferably a type SAE-J164 cap and serves as a pressure regulator for the reservoir  10 . The cap is a spring-loaded pressure cap that normally covers the overflow port  22  and prevents coolant and air from exiting the reservoir  10  via the overflow port. However, when a predetermined pressure develops in the reservoir  10 , a spring-loaded portion of the cap lifts slightly and uncovers the overflow port  22  such that excess pressurized gas and/or coolant (if the coolant level is sufficiently high) in the reservoir  10  can escape via the overflow port  22 . 
     The positioning of the discharge end of the overflow tube  58  at the bottom of the PWC&#39;s hull serves a second function. If a PWC having the coolant reservoir  10  flips over, coolant would not spill out because the external end of the overflow tube  58  would then be disposed at a higher elevation (now the bottom of the hull of the PWC) than the coolant reservoir  10 , itself. 
     Hereinafter, an alternative embodiment of the present invention will be described with reference to FIG.  6 . Where the embodiment illustrated in FIG. 6 is identical to the previous embodiment, the same reference numerals are used in order to avoid redundant descriptions of the common elements. Like the previous embodiment, an air escape passage  63  according to the present embodiment has a first end  63   a  operatively connected to the interior space  12  of the reservoir  65 . Unlike the previous embodiment, however, a second end  63   b  of the air escape passage  63  is operatively connected to the overflow tube  58  via the overflow port  67 . In the illustrated embodiment, the passage  63  is integrally formed with the reservoir  65 . However, the passage  63  could also comprise a separate tube that connects a port in the overflow port  67  to a port in the interior space  12 . In the present embodiment, a pressure-activated valve (not shown) is preferably disposed in the overflow tube  58  between the second end  63   b  and the discharge end of the overflow tube  58  so that gas and/or coolant does not escape through the escape passage  63  during use of the reservoir  65  unless a predetermined pressure builds up within the reservoir  65 . When the cap is removed and the reservoir  65  is filled with coolant, however, air can escape from the interior space  12  to the upper end  20   a  of the filling tube via the air escape passage  63  and overflow port  67 . 
     While in the illustrated embodiments, the second end  60   b ,  63   b  of the air escape passage  60 ,  63  connects to either the filling tube  20  or the overflow tube  58 , the second end of the air escape passage could also connect to a variety of other places without departing from the scope of the present invention. For example, the second end of the air escape passage could lead directly to the ambient environment outside the reservoir. Regardless of the specific structure employed, the goal of the air escape passage is to allow fluid to be added to the reservoir through the filling tube  20  at a substantially faster rate than air can escape from the reservoir through the air escape passage. 
     Hereinafter, the bleed port  24  and barrier  62  of the coolant reservoir  10  will be described with reference to FIGS. 2 and 3. 
     As can be seen in FIG. 2, a barrier  62  partially separates the interior space  12  of the reservoir  10  into first and second lateral interior spaces  12   a ,  12   b . The barrier  62  extends upwardly from the bottom of the interior space  12 . In the illustrated embodiment, the barrier  62  includes a lower portion  62   a  and an upper portion  62   b  that are separated by a small gap  62   c  formed in the barrier  62 . The lower portion  62   a  terminates below the filling tube  20  at an elevation slightly above a vertical middle of the interior space  12 . The upper portion  62   b  extends upwardly from a top of the gap  62   c  to the lower end  20   b  of the filling tube  20  and structurally reinforces the reservoir  10 . It should be noted that the upper portion  62   b  of the barrier  62  and/or the gap  62   c  may be omitted without deviating from the scope of the present invention. Furthermore, the barrier  62  could extend from and to various other vertical points within the interior space  12 , the purpose being that coolant below the top of the barrier  62  is discouraged from quickly flowing back and forth between the first and second lateral interior spaces  12   a ,  12   b . A coolant passage  64  operatively connects lower portions of the first and second lateral interior spaces  12   a ,  12   b  to allow coolant to gradually flow back and forth between the lower portions of the first and second interior spaces  12   a ,  12   b . The main coolant port  14  is disposed in the lower portion of the first lateral interior space  12   a . A bleed port  24  is operatively connected to an upper end above the second interior space  12   b.    
     As illustrated in FIG. 3, a bleed tube  66  is removably operatively connected to the bleed port  24  and operatively connected to the coolant path  34  at a location on the coolant path  34  just before the coolant leaves the engine  32  to return to the thermostat  36 . This location is the highest and hottest position along the coolant path  34  and is consequently a natural place for bubbles to develop and accumulate. 
     Hereinafter, the functionality of the barrier  62  will be described. The inventors of the present invention developed the barrier  62  and relative positioning of the reservoir  10  components in order to keep the coolant path  34  as bubble-free as possible. The first end of the bleed tube  66  is connected to the coolant path  34  where bubbles accumulate so that the bubbles accumulating in this area flow through the bleed tube  66  and into the second lateral interior space  12   b  via the bleed port  24 . Some of the bubbles may condense in the bleed tube  66  and splash down into the second lateral interior space  12   b  as coolant. The splashing coolant creates additional bubbles in the second lateral interior space  12   b . Because the bleed port  24  is disposed at an upper end of the second lateral space  12   b , the bubbles tend to stay in the upper portion of the interior space  12 . The barrier  62  limits flow between the first and second interior spaces  12   a ,  12   b  in order to discourage bubbles that enter the second lateral space  12   b  through the bleed port  24  from entering the first lateral space  12   a , especially when the coolant level within the reservoir  10  falls below the top of the barrier  62 . Because bubbles tend to move upward, the fluid passage  64 , which connects lower portions of the first and second lateral interior spaces  12   a ,  12   b , permits only a substantially bubbleless coolant in the lower portion of the second interior space  12   b  to flow into the first lateral interior space  12   a . Finally, the main coolant port  14  is disposed at the lower end of the first lateral interior space  12   a , which, for the reasons stated herein, is maintained relatively bubble-free. Consequently, bubbles that are formed in the second lateral space  121 ) or migrate to the second lateral space  12   b  by way of the bleed tube  66  and port  24  tend not to flow back into the coolant path  34  through the main coolant port  14 . 
     While the disclosed embodiment of the present invention is used in conjunction with a closed-loop coolant system  30 , the invention would work equally well with various other fluid systems that are known in the art. 
     The foregoing illustrated embodiments are provided to illustrate the structural and functional principles of the present invention and are not intended to be limiting. To the contrary, the principles of the present invention are intended to encompass any and all changes, alterations and/or substitutions within the spirit and scope of the following claims.