Abstract:
The present invention provides a multi-chamber fluid reservoir including two or more fluid chambers with thermal isolation between the chambers. The multi-chamber fluid reservoir is particularly suited for use in the cooling systems of internal combustion engines and is also suited for use in electric vehicles such as, for example, hybrid vehicles.

Description:
TECHNICAL FIELD 
       [0001]    This disclosure relates to a fluid reservoir particularly suited for closed loop coolant recirculation systems of motor vehicles and, more particularly related to a multi-chamber fluid reservoir providing thermal isolation between fluid chambers. 
       BACKGROUND OF THE INVENTION 
       [0002]    Fluid reservoirs are typically required for the proper operation of closed loop coolant circulation systems of internal combustion engines and hybrid vehicles. Coolant systems are configured to conduct heat away from the engine and drive components. Because many materials including fluids and coolants tend to expand in volume with increasing temperature and then later contract as they cool, it is advantageous to provide a fluid reservoir configured to hold excess fluid that may overflow the coolant system as the coolant temperature increases and then return the coolant into the coolant circulating system as the temperature decreases. 
         [0003]    Combination electric/internal combustion engine vehicles or so called “hybrid” vehicles are typically provided with rechargeable electric storage batteries which supply electrical energy to one or more electric drive motors as the driving source for the vehicle. To extend the operating range, the internal combustion engine may provide battery charging capabilities and/or vehicle drive capabilities when the remaining battery charge is low. 
         [0004]    Often hybrid vehicles require more than one coolant circulation or cooling system. These coolant systems may operate at different temperatures; different pressures and may in some cases utilize different coolant fluids. The internal combustion engine, if present, typically requires a dedicated closed loop coolant system. A separate closed loop coolant circulation system is often required to remove heat from the electrical storage and drive components of the vehicle. These components may include the batteries/battery racks, electric inverters and drive motors. It is typical that the operating coolant temperatures, operating pressures and in some cases even the coolant composition may differ between the coolant systems. 
         [0005]    It is advantageous to provide a fluid reservoir that embodies fluid reservoir and storage capabilities for all vehicle coolant systems within a single component. There remains a need in the art for a multi-chamber fluid reservoir configured to provide thermally and pressure isolated liquid storage and degassing capabilities for vehicles having multiple coolant systems. 
       SUMMARY OF THE INVENTION 
       [0006]    The present invention provides a multi-chamber fluid reservoir including two or more fluid chambers with thermal isolation between the chambers. The multi-chamber fluid reservoir is particularly suited to provide coolant storage and surge capacity to the closed loop cooling systems of motor vehicles, including hybrid vehicles. 
         [0007]    The multi-chamber fluid reservoir apparatus according to the present inventive disclosure includes a first chamber housing defining a first liquid storage chamber within and at least a second chamber housing defining a second liquid storage chamber within. Additional chamber housings may also be included in the reservoir apparatus as needed. At least some of the chamber housings are spatially separated, defining a thermal isolation gap between the chamber housings. To reduce thermal conduction between the fluid chambers, it is preferred that adjacent chamber housings do not share common outer walls. 
         [0008]    A thermal isolation web is provided entending between the first and second housings across the thermal isolation gap. The thermal isolation web maintains the spatial separation of the chamber housings and supportively couples at least the first and second chamber housings. The thermal isolation web is preferably made of a material substantially non-conductive to the transfer of heat and is operative to minimize conductive heat transfer between the liquid chambers. 
         [0009]    Chamber housings may include a fill port fitting arranged on an outer wall and having a flow aperture extending therethrough into the liquid chamber therein to permit fluids such as coolant to be added to the coolant system. The fill port fitting is preferably threaded or adapted to retentively receive a pressure cap or closure cap thereon. Chamber housings may include a liquid outlet fitting preferably arranged on a lower portion of an outer wall and having a flow aperture extending therethrough into the liquid chamber therein. The outlet fitting is typically fluidically connected directly or indirectly to the cooling system to deliver fluid to or receive fluid from the coolant system. 
         [0010]    According to another aspect of the invention, the first and second liquid chambers operate at different pressures and/or differing temperatures. 
         [0011]    According to another aspect of the invention, at least two chamber housings include pressure caps removeably secured to the fill port and the pressure caps are provided with differing defined pressure settings. In this configuration the pressure caps are operative to open and permit flow from the fluid chamber when the defined pressure setting is reached or exceeded, thereby establishing a maximum operating pressure of the chamber housing and connected cooling system. 
         [0012]    According to another aspect of the invention, at least one of the chamber housings may include an overflow fitting preferably arranged on an upper portion of an outer wall and having a flow aperture extending therethrough into the liquid chamber therein. 
         [0013]    According to another aspect of the invention, the fluid reservoir is assembled from a plurality of mated reservoir portions which, when assembled, form the multi-chamber fluid reservoir consistent with the present inventive disclosure. Each portion includes flanges configured to mateably secure to the complimentary configured flanges arranged on the neighboring reservoir portions. Preferably, the mating flanges are of a plastic material that may be secured together by a securing means such as: hot plate welding, vibration welding, laser welding, or adhesives. 
         [0014]    According to another aspect of the invention, the thermal isolation web and connected chamber housings are arranged in a first axial direction and the flanges are aligned transverse to this first axial direction. The transverse aligned flanges advantageously configure the mating reservoir portions to be tooled vertically for plastic injection molding. 
         [0015]    According to another aspect of the invention, the thermal isolation web includes at least one flow passage extending between and interconnecting the first and second chambers. Preferably the flow passage is formed directly into or formed on the thermal isolation web. 
         [0016]    According to another aspect of the invention, at least one of the flow passages is regulated by a first one-way flow valve arranged in the thermal isolation web and configured to permit liquid flow in the flow passage only in one direction. 
         [0017]    According to another aspect of the invention, one of the at least one flow passages includes a second one-way flow valve arranged in the thermal isolation web and configured to permit liquid flow in a direction opposite to the direction of flow in the first one-way valve. 
         [0018]    According to another aspect of the invention, the first one-way flow valve includes a spring operative to hold the one-way valve closed. When a predefined pressure differential across the valve is exceeded, the fluid pressure overcomes the force of the spring permitting the valve to open and the fluid to flow in the flow passage between the connected fluid chambers. 
         [0019]    According to another aspect of the invention, the fluid reservoir is configured to provide pressure and flow isolation between the liquid chambers. 
         [0020]    The above features and advantages and other features and advantages of the present invention are readily apparent from the following detailed description of the best modes for carrying out the invention when taken in connection with the accompanying drawings. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0021]    The accompanying Figures, where like reference numerals refer to identical or functionally similar elements throughout the separate views and which together with the detailed description below are incorporated in and form part of the specification, serve to further illustrate various embodiments and to explain various principles and advantages all in accordance with the present invention. 
           [0022]    Features of the present invention, which are believed to be novel, are set forth in the drawings and more particularly in the appended claims. The invention, together with the further objects and advantages thereof, may be best understood with reference to the following description, taken in conjunction with the accompanying drawings. The drawings show a form of the invention that is presently preferred; however, the invention is not limited to the precise arrangement shown in the drawings. 
           [0023]      FIG. 1A  is an exploded side sectional view of an example embodiment of a multi-chamber fluid reservoir incorporating features of the present inventive disclosure, consistent with the present invention; 
           [0024]      FIG. 1B  is an assembled side view of the reservoir of  FIG. 1A ; 
           [0025]      FIG. 2  is a top view of the reservoir of  FIG. 1B ; and 
           [0026]      FIG. 3  depicts a schematic depiction of a further exemplary embodiment of the multi-chamber reservoir  110  including one-way flow valves, consistent with the present invention. 
       
    
    
       [0027]    Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention. 
       DETAILED DESCRIPTION 
       [0028]    Before describing in detail embodiments that are in accordance with the present invention, it should be observed that the embodiments reside primarily in combinations of method steps and apparatus components related to a multi-chamber fluid reservoir for a vehicle, for example a hybrid vehicle, as disclosed herein. Accordingly, the apparatus components have been represented where appropriate by conventional symbols in the drawings, showing only those specific details that are pertinent to understanding the embodiments of the present invention so as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having the benefit of the description herein. 
         [0029]    In this document, relational terms such as first and second, top and bottom, and the like may be used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. The terms “comprises,” “comprising,” or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. An element preceded by “comprises . . . a” does not, without more constraints, preclude the existence of additional identical elements in the process, method, article, or apparatus that comprises the element.  FIG. 1A  is an exploded side sectional view of a multi-chamber fluid reservoir  10  incorporating features of the present inventive disclosure.  FIG. 1B  is an assembled side view of the reservoir of  FIG. 1A .  FIG. 2  is a top view of the reservoir of  FIG. 1B . The multi-chamber fluid reservoir  10  provides thermally isolated and, in some embodiments, pressure isolated fluid reservoirs within a single unitary component. The multi-chamber fluid reservoir  10  may advantageously be applied to provide fluid surge and storage capacity for a plurality of discrete, independent coolant systems, potentially with each system operating at differing temperatures and/or pressures and potentially utilizing differing coolant fluids. The exemplary illustrated reservoir  10  may include a first chamber housing  12  having outer walls  48  defining a first fluid chamber  12  within. The reservoir  10  includes one or more additional fluid chamber housings, such as second chamber housing  16  having outer walls  50  defining a second fluid chamber  18  within. Although  FIG. 1A  shows flow passage  44  interconnecting chamber housings  12  and  16 , this feature is only present in some embodiments and, when present, the flow passage  44  may advantageously include one-way valves or other control valves to provide pressure and flow isolation in addition to temperature isolation between the fluid chambers. 
         [0030]    In  FIGS. 1A-2 , the first fluid chamber  12  is shown as axially spaced apart from the second fluid chamber  18  in a first axial direction  42 . 
         [0031]    For manufacturing it may be advantageous to configure the multi-chamber reservoir  10  as an assembly of separate reservoir portions, for one example mateable reservoir portions  38 A,  38 B and  38 C as shown in  FIG. 1A . Such a segmentation of the reservoir  10  advantageously adapts the reservoir to be readily injection molded as a series of open cup-shaped or clamshell shaped housing pieces. Although  FIGS. 1A and 1B  depict three mateable reservoir portions  38 A,  38 B,  38 C forming two thermally isolated and spaced apart fluid chambers  14  and  18 , it is to be understood that this simplified configuration is only depicted as an example for enablement and to provide the reader with a better understanding of the inventive concepts presented herein. As may be readily understood, multi-chamber fluid reservoirs according to the present inventive disclosure may be configured with any number of reservoir portions and any number of fluid chambers as may be advantageous to meet the requirements of a particular fluid reservoir application. 
         [0032]    The multi-chamber reservoir  10  may be produced by injection molding of a plastic material such as polycarbonate although other suitable materials may be used instead. 
         [0033]    As can be seen in  FIGS. 1B and 2 , the chamber housings  12  and  16  are illustrated as spaced apart along a first axial direction  42 , the spatial distance identified by a thermal isolation gap  20 . Due to the thermal isolation gap  20  separating the first chamber housing  12  and second chamber housing  16 , advantageously the chamber housings  12  and  16  do not share common outside walls, specifically outer walls  48 A and  50 A are spatially separated walls that do not contact and do not share common wall components. The thermal isolation gap  20  is advantageously operative to minimize the conduction of thermal energy (heat) between the contents of the first fluid chamber  14  and the contents of the second fluid chamber  18 . This is particularly advantageous when the cooling systems to which these chambers are fluidically connected operate at significantly different temperatures. Additionally, fluids in fluid chambers  14  and  18  may flow in and out of their respective chambers only on an infrequent basis, and so these fluids may be expected to remain within the fluid chambers  14  and  18  for an extended period of time. The thermal isolation gap  20  substantially eliminates heat transfer between the chamber housings  12  and  16 , thereby preventing heat transfer between what may be relatively static fluids (fluids with long residence times) within the first  14  and second  18  fluid chambers. 
         [0034]    In the exemplary embodiment depicted in  FIGS. 1A-2 , the chamber housings  12  and  16  are supportively and structurally interconnected by a thermal isolation web  22  such that the multi-chambers are realized as a single one-piece component. The thermal isolation web  22  is secured at one end to the outer wall  48 A of the first chamber housing  12  as well as at its opposing end to the outer wall  50 A of the second chamber housing  16 , thereby structurally interconnecting these chambers to form a unitary multi-chamber reservoir  10 . 
         [0035]    Preferably, the thermal isolation web  22  is realized as a thin cross-section component such as, for one example, a thin plate-like sheet. The thin cross-section of the thermal isolation web  22  is best seen in  FIG. 2 . The thin cross section is advantageous to further reduce heat conduction between the chamber housings  12  and  16  through the thermal isolation web  22 . While the thermal isolation web may be provided with other cross sectional shapes such as for structural strength reasons, it is advantageous to maintain the cross section as thin as practical. Further thermal isolation of the chamber housings  12  and  16  is provided by the spatial separation of the chamber housings provided by the length of the thermal isolation web  22 . 
         [0036]    In the embodiment depicted in  FIGS. 1A-2 , advantageously the thermal isolation web  22  may be formed as a unitary component with the separated outer walls  48 A and  50 A during the injection molding process. 
         [0037]    It is further envisioned that in some embodiments the thermal isolation web  22  may be provided with one or more fluid flow passages formed thereon or therein, for example fluid flow passage  44 . In the embodiment illustrated in  FIG. 1A , fluid flow passage  44  fluidically interconnects the first fluid chamber  12  to the second fluid chamber  18 , permitting the overflow or other passage of fluid between the first  12  and second  18  fluid chambers. 
         [0038]    In cases where the fluid reservoir chambers operate at differing pressures or temperatures and when on one or more flow passages  44  interconnect the chambers, it may be advantageous to limit or regulate potential fluid flow between the chambers by providing, for example, a one-way flow valve or alternately a pressure relief valve in any of the flow passages, such as flow passage  44 . 
         [0039]    For a further example,  FIG. 3  provides a schematic depiction of a further exemplary embodiment of a multi-chamber reservoir  110  having two isolated reservoir chambers  114  and  116 . Multi-chamber reservoir  110  includes a first chamber housing  112  and a spatially separated second chamber housing  116  interconnected by a thermal isolation web  122 . Thermal isolation web  122  includes two flow passages  44 A and  44 B configured to fluidically interconnect the fluid chambers  114  and  116 . In one advantageous embodiment, flow passage  44 A maybe include a one-way flow valve  54  permitting fluid to flow through one-way flow valve  54  from the first chamber housing  112  to the second chamber housing  116 . One-way flow valve  54  may be configured as a pressure relief valve by including a spring selected to hold the one-way valve  54  in a closed position until a pre-defined pressure differential across the valve  54  is exceeded, thereby overcoming the closing force of the spring. In this case, the one-way flow valve  54  and flow passage  44 A provide the first chamber housing with a fluid pressure relief or overflow path into the second chamber housing  116 . 
         [0040]    For a further example, the flow passage  44 B is depicted with another one-way flow valve  56  configured to permit fluid to flow from chamber housing  116  into chamber housing  112 , but not permitting fluid to flow in the reverse direction. If the one-way flow valve  56  is adapted to open with a relatively low pressure differential, that is it functions more like a check valve or one-way flow valve, then the combination of flow passages  44 A and  44 B permit the chamber housing  116  to provide the function of an overflow reservoir to housing chamber  112 . Fluid may overflow from chamber housing  112  into chamber housing  116  through flow passage  44 A with fluid later returning to chamber housing  112  through flow passage  44 B of thermal isolation web  122 . The one-way valves regulate flow between the chambers in normal operating conditions, thereby assuring the chambers remain pressure and temperature isolated. In other embodiments the valves  54  and  56  may be configured to open at a very low or a more elevated pressure as may be advantageously suited to the intended application. 
         [0041]    In the foregoing specification, specific embodiments of the present invention have been described. However, one of ordinary skill in the art appreciates that various modifications and changes can be made without departing from the scope of the present invention as set forth in the claims below. Accordingly, the specification and figures are to be regarded in an illustrative rather than a restrictive sense, and all such modifications are intended to be included within the scope of the present invention. The benefits, advantages, solutions to problems, and any element(s) that may cause any benefit, advantage, or solution to occur or become more pronounced are not to be construed as critical, required, or essential features or elements of any or all the claims. The invention is defined solely by the appended claims including any amendments made during the pendency of this application and all equivalents of those claims as issued.