Patent Publication Number: US-2011073285-A1

Title: Multi-Zone Heat Exchanger for Use in a Vehicle Cooling System

Description:
BACKGROUND OF INVENTION 
     The present invention relates generally to fluid cooling systems employed with automotive vehicles. 
     A condenser, radiator, fan module (CRFM) for an automotive vehicle typically includes several separate heat exchangers for cooling fluids that flow through various vehicle subsystems. In more recent vehicles, such as hybrid vehicles, with an increase in the number of subsystems the number of cooling loops has increased, and thus the number of heat exchangers in the CRFM has also increased. Moreover, each of these heat exchangers is sized to meet the cooling requirements for its respective cooling loop under that particular loop&#39;s peak load conditions. These heat exchangers, then, take up more packaging space in the CRFM than is desired. Consequently, it is desirable to meet the peak cooling demands for each of the cooling loops while reducing the packaging space required for heat exchangers in the CRFM. 
     SUMMARY OF INVENTION 
     An embodiment contemplates a multi-zone cooling system for use in a vehicle. The cooling system may comprise a multi-zone heat exchanger, a first cooling loop and a second cooling loop. The multi-zone heat exchanger may have a first zone, a second zone and a third zone, a first one-way check valve between the first zone and the second zone configured to only allow fluid flow from the first zone to the second zone and a second one-way check valve between the third zone and the second zone configured to only allow fluid flow from the third zone to the second zone, a zone one fluid inlet, a zone one fluid outlet, a zone three fluid inlet, a zone three fluid outlet, a first zone two fluid outlet and a second zone two fluid outlet. The first cooling loop may include a first three-way valve having a first inlet for receiving fluid flow from the zone one fluid outlet, a second inlet for receiving fluid flow from the first zone two fluid outlet and a valve outlet, with the first three-way valve being controllable to selectively block fluid flow from one or the other of the first inlet and the second inlet. The second cooling loop may include a second three-way valve having a third inlet for receiving fluid flow from the zone three fluid outlet, a fourth inlet for receiving fluid flow from the second zone two fluid outlet and a valve outlet, with the second three-way valve being controllable to selectively block fluid flow from one or the other of the third inlet and the fourth inlet. 
     An embodiment contemplates a multi-zone cooling system for use in a vehicle that may comprise a multi-zone heat exchanger having a first zone, a second zone and a third zone; a first cooling loop that provides a flow of a fluid through a first vehicle component to cool the first vehicle component, with the first cooling loop configured to direct fluid flow from the first cooling loop into the first zone; a second cooling loop that provides a flow of the fluid through a second vehicle component to cool the second vehicle component, with the second cooling loop configured to direct fluid flow from the second cooling loop into the third zone; a first valve that selectively allows for fluid flow from one or the other of the first zone and the second zone into the first cooling loop; a second valve that selectively allows for fluid flow from one or the other of the third zone and the second zone into the second cooling loop; and a controller engaging the first and second valves to control switching of the first and second valves. 
     An embodiment contemplates a method of operating a multi-zone cooling system in a vehicle including a first cooling loop for providing cooling for a first vehicle component and a second cooling loop for providing cooling for a second vehicle component, the method comprising the steps of: (a) directing fluid flow from the first cooling loop into a first zone of a multi-zone heat exchanger and back into the first cooling loop from the first zone during a first operating condition for the first vehicle component; (b) directing fluid flow from the second cooling loop into a third zone of the multi-zone heat exchanger and back into the second cooling loop from the third zone during a first operating condition for the second vehicle component; (c) directing fluid flow from the first cooling loop into the first zone of the multi-zone heat exchanger, from the first zone to a second zone of the multi-zone heat exchanger and back into the first cooling loop from the second zone during a first cooling loop peak operating condition where peak cooling for the first vehicle component is needed; (d) while performing step (c), directing fluid flow from the second cooling loop into the third zone of the multi-zone heat exchanger and back into the second cooling loop from the third zone during the first operating condition for the second vehicle component; (e) directing fluid flow form the second cooling loop into the third zone of the multi-zone heat exchanger, from the third zone to the second zone of the multi-zone heat exchanger and back into the second cooling loop from the second zone during a second cooling loop peak operating condition where peak cooling for the second vehicle component is needed; and (f) while performing step (e), directing fluid flow from the first cooling loop into the first zone of the multi-zone heat exchanger and back into the first cooling loop from the first zone during the first operating condition for the first vehicle component. 
     An advantage of an embodiment is that a reduced number of heat exchangers is employed in the CRFM of the vehicle while still providing adequate cooling for peak cooling loads of the various cooling loops. This reduced number of heat exchangers may reduce the cost and improve the packaging of the CRFM in the vehicle. 
     An advantage of an embodiment is that two separate coolant loops using the same coolant and seeing peak loads typically under distinct operating conditions will operate through different zones of a single heat exchanger, with a shared zone that provides the additional cooling capacity to account for the distinct peak load conditions of the two loops. In effect, additional reserve cooling capacity is available for either loop when a high cooling load condition arises for one of the two loops, allowing for variable cooling capacity for each of these two loops. In effect, this one multi-zone heat exchanger acts as essentially four heat exchangers, while minimizing the packaging space. 
     An advantage of an embodiment may be that the use of the multi-zone heat exchanger may allow for a reduction in vehicle drag, a reduction in engine fan coolant pump power consumption, and a reduced overall pressure drop in the fluids across the CRFM. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a schematic diagram of a portion of a vehicle. 
         FIG. 2  is a schematic diagram of portions of a multi-zone cooling system operating in a first mode. 
         FIG. 3  is a schematic diagram similar to  FIG. 2 , but shown operating in a second mode. 
         FIG. 4  is a schematic diagram similar to  FIG. 2 , but shown operating in a third mode. 
     
    
    
     DETAILED DESCRIPTION 
     Referring to  FIGS. 1 and 2 , a portion of a vehicle  20  is schematically illustrated. The vehicle  20  may include several types of cooling systems, such as, for example, a transmission oil cooling system  22 , a refrigerant system  24  for a heating ventilation and air conditioning (HVAC) system, and a multi-zone cooling system  26 . Typically, these cooling systems will have heat exchangers mounted near a front opening of the vehicle in what is commonly called a condenser, radiator, fan module (CRFM)  28 . The transmission oil cooling system  22  may include a heat exchanger  30  (oil cooler) mounted in the CRFM  28  for cooling oil in a transmission oil loop  32  that brings transmission oil from and sends it back to a transmission (not shown). The refrigerant system  24  may include a condenser  34  mounted in the CRFM  28  for removing heat from refrigerant flowing through a refrigerant loop  36 . The CRFM  28  also includes a fan  38  that is employed to draw air through the heat exchangers in the CRFM  28 . 
     The multi-zone cooling system  26  includes a multi-zone heat exchanger  40  that may be contained in the CRFM  28  and is connected to two different cooling loops, a first cooling loop  42  and a second cooling loop  44 . The first cooling loop  42  may be, for example, an internal combustion engine coolant loop and may contain a conventional type of coolant mixture, such as water and ethylene glycol. This coolant loop  42  may direct the coolant through, for example, an internal combustion engine  50  and an HVAC heater core (not shown). This cooling loop may be employed to cool a different component or subsystem, if so desired, such as, for example, a battery pack or battery related electronics components. The term “component” as used herein when referring to items cooled by the cooling loop includes a subsystem or subsystems and just refers to one or more items being cooled by the fluid in that particular loop. The first cooling loop  42  may include an electronically controllable pump  46  for pumping the coolant through the loop  42 , and an electronically controllable 3-way valve  48  for redirecting the coolant flow through the loop  42 . 
     The second cooling loop  44  may be a powertrain electronics cooling loop containing the same coolant mixture as the first cooling loop  42 . This coolant loop  44  may direct the coolant through, for example, powertrain electronics such as a traction power inverter module  52 . The second cooling loop  44  may include an electronically controllable pump  54  for pumping the coolant through the loop  44 , and an electronically controllable 3-way valve  56  for redirecting the coolant flow through the loop  44 . The valves  48 ,  56  may be separate from, mounted on or mounted in the multi-zone heat exchanger  40 . 
     An electronic controller  58  may be connected to and control the operation of the pumps  46 ,  54  and the valves  48 ,  56  (as indicated by dotted lines in  FIG. 1 ). The controller may be separate from or part of another vehicle controller, such as a powertrain control module, and may be made up of any combination of hardware and software as is known to those skilled in the art. 
     The multi-zone heat exchanger  40  interacts with both the first and second cooling loops  42 ,  44 . This heat exchanger  40  is a single heat exchanger that is divided up into three zones, a first zone  60 , a second zone  62  and a third zone  64 . The coolant in the heat exchanger  40  cannot flow from the first zone  60  into the second zone  62  except through a zone  1 - 2  one-way check valve  66 , and cannot flow from the second zone  62  directly back into the first zone  60  (i.e., without flowing through the first cooling loop  42 ). The coolant in the heat exchanger  40  cannot flow from the third zone  64  into the second zone  62  except through a zone  3 - 2  one-way check valve  68 , and cannot flow from the second zone  62  directly back into the third zone  64  (i.e., without flowing through the second cooling loop  44 ). In addition, the heat exchanger  40  does not allow for coolant flow directly between the first zone  60  and the third zone  64 . 
     The multi-zone heat exchanger  40  also includes a zone one inlet  70  into the first zone  60  that receives fluid flow from the pump  46  in the first cooling loop  42 , a zone one outlet  72  that directs fluid flow from the first zone  60  toward a first inlet of the 3-way valve  48  in the first cooling loop  42 , and a first zone two outlet  74  that directs fluid flow from the second zone  62  toward a second inlet of the 3-way valve  48  in the first cooling loop  42 . An outlet  76  from the 3-way valve  48  directs the fluid into the rest of the first cooling loop  42  (such as the internal combustion engine  50 ). Alternatively, the pump  46  may be located between the 3-way valve  48  and the internal combustion engine  50  rather than between the engine  50  and the zone one inlet  70 , if so desired. 
     A zone three inlet  78  into the third zone  64  receives fluid into the third zone  64  from the pump  54  in the second cooling loop  44 , a zone three outlet  80  directs fluid flow from the third zone  64  toward a first inlet of the 3-way valve  56  in the second cooling loop  44 , and a second zone two outlet  82  directs fluid flow from the second zone  62  toward a second inlet of the 3-way valve  56 . An outlet  84  from the 3-way valve  56  directs the fluid into the rest of the second cooling loop  44  (such as the traction power inverter module  52 ). Alternatively, the pump  54  may be located between the 3-way valve  56  and the traction power inverter module  52  rather than between the inverter module  52  and the zone three inlet  78 , if so desired. 
     Thus, for fluid flow, the first zone  60  is always connected to the first cooling loop  42 , the third zone  64  is always connected to the second cooling loop  44  and the second zone  62  may be connected to one of the first or second loops  42 ,  44  or to neither of the cooling loops. This allows for three distinct modes of coolant cooling for the multi-zone heat exchanger  40  as it interacts with the first and second cooling loops  42 ,  44 . 
     The arrow heads on the fluid lines in  FIGS. 1 and 2  show the flow of fluids for a first operating mode. In this mode, the first and second cooling loops  42 ,  44  are both operating under normal cooling loads. The pumps  46 ,  54  are activated, the first 3-way valve  48  is set to direct fluid flow from the zone one outlet  72  through to the 3-way valve outlet  76  and block flow from the first zone two outlet  74 , and the second 3-way valve  56  is set to direct fluid flow from the zone three outlet  80  through to the 3-way valve outlet  84  and block flow from the second zone two outlet  82 . Accordingly, the coolant in the first cooling loop  42  only flows through the first zone  60  and the coolant in the second cooling loop  44  only flows through the third zone  64 . Fluid is not flowing through the second zone  62  and so this zone does not contribute to the cooling of the coolant. While the cooling capacity of the first zone  60  is less than the peak needed for cooling in the first cooling loop  42  under peak load conditions, the heat exchanger capacity in first zone  60  is sized to be sufficient to meet the cooling demands under normal load conditions for the first cooling loop  42 . The same is true for the third zone  64  and the second cooling loop  44 . 
       FIG. 3  illustrates a second operating mode where the first cooling loop  42  is operating under peak cooling load conditions and the second cooling loop is operating under normal cooling load conditions. For example, the engine  50  may require peak cooling while the traction power inverter module  52  only requires normal cooling. In this operating mode, the pumps  46 ,  54  are activated, the first 3-way valve  48  is switched to direct fluid flow from the first zone two outlet  74  through to the 3-way valve outlet  76  and block flow from the zone one outlet  72 , and the second 3-way valve  56  is set to direct fluid flow from the zone three outlet  80  through to the 3-way valve outlet  84  and block flow from the second zone two outlet  82 . Accordingly, the coolant in the second cooling loop  44  only flows through the third zone  64  of the multi-zone heat exchanger  40 . However, the coolant in the first cooling loop  42  now flows through the first zone  60 , through the zone  1 - 2  check valve  66  and through the second zone  62 . This flow through two zones of the heat exchanger  40  significantly increases the cooling capacity, thus meeting the peak cooling requirements for the first cooling loop  42 . The zone  2 - 3  check valve  68  will block the flow of the coolant from the second zone  62  into the third zone  64 . Also, if so desired, the pump  46  may be variable capacity and be adjusted to further improve the cooling in the first cooling loop  42  under peak cooling load conditions. 
       FIG. 4  illustrates a third operating mode where the first cooling loop  42  is operating under normal cooling load conditions and the second cooling loop is operating under peak cooling load conditions. For example, the engine  50  may only require normal cooling while the traction power inverter module  52  requires peak cooling. In this operating mode, the pumps  46 ,  54  are activated, the first 3-way valve  48  is set to direct fluid flow from the zone one outlet  72  through to the 3-way valve outlet  76  and block flow from the first zone two outlet  74 , and the second 3-way valve  56  is set to direct fluid flow from the second zone two outlet  82  through to the 3-way valve outlet  84  and block flow from the zone three outlet  80 . Accordingly, the coolant in the first cooling loop  42  only flows through the first zone  60  of the multi-zone heat exchanger  40 . However, the coolant in the second cooling loop  44  now flows through the third zone  64 , through the zone  3 - 2  check valve  68  and through the second zone  62 . This flow through two zones of the heat exchanger  40  significantly increases the cooling capacity, thus meeting the peak cooling requirements for the second cooling loop  44 . The zone  1 - 2  check valve  66  will block the flow of the coolant from the second zone  62  into the first zone  60 . Also, if so desired, the pump  54  may be variable capacity and be adjusted to further improve the cooling in the second cooling loop  44  under peak cooling load conditions. 
     For operation of this multi-zone cooling system  26  in the vehicle  20 , the first and second cooling loops will have the same coolant mixture and the peak load conditions of these loops will have little to no overlap (i.e., when one loop demands peak cooling capacity the other can be managed with a much more reasonable cooling capacity). In addition, while this embodiment has been discussed with two cooling loops interacting with the multi-zone heat exchanger  40 , it is contemplated that another embodiment could have, for example, a third cooling loop and the addition of another zone, check valve, pump, 3-way valve and corresponding inlets and outlets from the heat exchanger  40 . 
     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.