Abstract:
A thermal management module includes a motor with an output shaft, and a gear train connecting the output shaft to a driven gear connected to a valve for controlling coolant flow in a coolant system. At least one grille shutter is movable between an open position allowing air through the grille shutter and a dosed position preventing air through the grille shutter. A linkage connects the at least one grille shutter to the output shaft or the gear train, so that the motor is operable to control a valve operating position of the valve and a shutter operating position of the at least one shutter.

Description:
FIELD OF INVENTION 
     The present invention relates to a thermal management module of a cooling system of an internal combustion engine that controls both coolant flow within the cooling system and air flow. 
     DESCRIPTION OF THE PRIOR ART 
     US 2011/0162595 is an example of a heat management module for a cooling system of an internal combustion engine. This reference discloses switching between two coolant circuits. A bypass circuit returns coolant to the internal combustion engine and a radiator circuit directs to coolant through the radiator. The coolant flow is directed to either one or both of circuits by specific distribution to adjust the internal combustion engine to an optimum coolant temperature. 
     US 2010/0243352 discloses a further type of heat management for a motor vehicle referred to as active grill shutters (AGS). According to this reference, a plurality of louvers or shutters is disposed on the motor vehicle to control air flow through a front grille opening into an engine compartment. The AGS system allows airflow through the grille when demand on the cooling system or air conditioning is high. In addition, the active grille shutters may also be activated at higher speeds to reduce drag. 
     To utilize both the heat management module and the AGS system in a vehicle, two separate motors, cabling, and power electronics must be added to vehicles that are already complex and crowded. 
     SUMMARY OF THE INVENTION 
     An object of the present invention is to provide a heat management module and an AGS system while minimizing the installation space, mass, and cost. 
     The object of the present invention is met by a thermal management module comprising a motor having an output shaft, a gear train connecting the output shaft to a driven gear connected to a valve for controlling coolant flow in a coolant system, at least one grille shutter movable between an open position allowing air through the grille shutter and a closed position preventing air through the grille shutter, and a linkage connecting the at least one grille shutter to at least one of the output shaft and the gear train, so that the motor is operable to control a valve operating position of the valve and a shutter operating position of the at least one shutter. 
     According to an embodiment of the invention, the year train is an existing gear train for a Thermal Management Module that is adapted to control an AGS system. The existing gear train includes a worm gear meshed with a driven gear connected to drive the valve. An extension of the worm gear shaft is added and is operatively connected to drive the linkage, which comprises a crank driven to rotation by the extension. The crank is connected to the extension by a one way clutch so that a clockwise rotation causes the crank to rotate and a counter clockwise rotation causes the one way clutch to freewheel. Instead of an existing gear train, the module may include another gear train optimized for driving both a Thermal Management Module valve and shutters of an AGS system. Instead of a worm gear, such module may alternatively use a pinion gear. 
     A gear ratio of the worm gear or pinion gear rotation to the driven gear is configured so that multiple rotations of the worm gear or the pinion gear are required to move the valve from an open valve position to a closed valve position. The grille shutter cycles between the open shutter position and the closed shutter position during each of the multiple rotations. As an alternative, a different gear ratio between the grille shutter cycles and worm gear or pinion gear may be used. However, the ratio of the grill shutter cycle to the valve stroke should be relatively large such that small adjustments can be made to the grille shutter operating position with minimal changes to the valve operating position. 
     According to another embodiment, a controller is operatively connected to the motor to control the valve operating position and the shutter operating position. A latching mechanism includes a spring with a tab, and a protrusion on the crank that interacts with the tab during each cycle of the crank. During each rotation of the crank, the interaction of the tab and the protrusion causes an increase in electric power drawn by the motor that is sensed by the controller. The controller uses this cyclical power increase to determine the point at which the tab releases the crank and thus determine a position of the crank and the shutter. 
     Instead of the latching mechanism, a sensor may alternatively be used to monitor the crank position. 
     Instead of using the one way clutch, a clutch may be configured to selectively connect the motor output shaft to the linkage and the gear train. According to one embodiment, a solenoid acts on one of the motor output shaft and the clutch, such that the clutch connected to drive the gear train when the solenoid is not actuated and the clutch is connected to drive the linkage when the solenoid is actuated. In a preferred embodiment, the solenoid is actuated when it is energized. However, the solenoid may alternatively be de-energized to actuate. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       In the drawings, wherein like references denote similar elements throughout the several views: 
         FIG. 1A  is a schematic diagram of a cooling system for an internal combustion engine with a thermal management module; 
         FIG. 1B  is a schematic perspective view of the thermal management module of  FIG. 1A ; 
         FIG. 2  is a schematic diagram showing the thermal management module according to an embodiment of the present invention; 
         FIG. 3A  is a top view of a latching mechanism according to an embodiment of the present invention; 
         FIG. 3B  is a side view of the latching mechanism according to  FIG. 3A ; 
         FIG. 3C  is a graph illustrating the shutter position and the torque during two revolutions of the crank; 
         FIG. 4  is a block diagram of an embodiment of the present invention; and 
         FIG. 5  is a schematic diagram of another embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       FIG. 1A  shows a cooling system for an internal combustion engine (ICE)  101  that includes a radiator circuit  102  and a bypass circuit  103 . The radiator circuit  102  conducts fluid that has been heated by the ICE  101  to a radiator  104 , which cools the fluid. The fluid is returned to the ICE  101  by a pump  105 . The bypass circuit  103  is used to heat up the ICE  101  by bypassing the radiator  104 . A heat management module  106  receives feeds from both the radiator circuit  102  and the bypass circuit  103  and outputs fluid from the radiator circuit  102 , the bypass circuit  103 , or a mixture thereof to the ICE  101 . 
       FIG. 1B  shows that the heat management module  106  includes a valve housing  107  having a first feed connection  108  receiving fluid from the bypass circuit  103  and a second feed connection  109  receiving fluid from the radiator circuit  102 . Depending on the position of valve member  3 , the first and second feed connections  108 ,  109  are selectively connected to discharge connection  111 , which is connected to the ICE  101 . 
       FIGS. 1B and 2  show that the heat management module includes a motor driven worm gear  1  connected to a driven gear  2  of the valve member  3 . The valve member  3  offers the ability to control coolant flow to the radiator and ICE as described above, and may additionally or alternatively control flow to a heater, and/or a turbo charger, to enable faster warmup of the engine and transmission and improving fuel economy. A shaft  7  of the worm gear  1  is driven by a motor  4  to control the position or the valve member  3 . 
     As shown in  FIG. 2 , the shaft  7  of the worm gear is also connected to a crank  5  by a one-way clutch (OWC)  6 . The worm gear shaft  7  drives the crank  5  in only one direction (see the arrow A in  FIG. 3A ) via the OWC  6 . As explained in more detail below, the crank  5  is connected by a linkage to an active grille shutter (AGS) system. Thus, the motor  4  is used to operate both the valve member  3  and the AGS system, 
     A controller  25  is operatively connected to the motor  4  to control the position of the valve member  3  and of the AGS system (see also  FIG. 4 ). When the controller  25  controls the motor  4  to rotate the worm shaft clockwise (ref.  FIG. 3A ), the OWC  6  is in freewheel mode and the crank  5  does not rotate. The crank  5  is maintained in position to hold the AGS system at a constant position during the freewheel mode by a friction washer  15  disposed between the crank  5  and a housing  8 . A spring  17 , such as a plate spring, is mounted between the crank  5  and a stop disk  18  arranged on the shaft  7  to urge the crank  5  against the friction washer  15 . The crank  5  is connected to at least one shutter  24  of the AGS system by a cable  9 , i.e., a Bowden cable. While the preferred embodiment includes the cable  9 , a plastic rod or any other known or hereafter developed linkage may alternatively be used to connect the crank  5  to the AGS system. When controller  25  controls the motor  4  to rotate the worm shaft  7  counter clockwise, the OWC  6  is engaged and the crank  5  is rotated and the linkage cable  9  is moved to change the position of the AGS shutter  24  that is moved between an open shutter position and a dosed shutter position. 
     In the embodiment shown, a gear ratio of the worm clear  1  to the driven gear  2  is configured so that the worm gear  1  rotates a plurality of times during movement of the valve member  3  from an open valve position to a closed valve position. Thus, when the worm shaft  1  is rotated counter clockwise the crank  5  creates a cyclic motion between the open shutter position and the dosed shutter position. To select independent positions of the valve member  3  and AGS shutters  24 , the controller  25  operates the motor  4  so that the desired valve position is over shot during a counter clockwise rotation to the desired position of the AGS shutter  24 , and is then rotated clockwise back to the desired valve position without further affecting the position of the AGS shutter  24 . When the valve member  3  must be adjusted by a clockwise rotation, the controller  25  operates the motor  4  so that the valve member  3  is adjusted past the desired valve position by the change in AGS position desired. When the shaft  7  is rotated clockwise, the AGS position is adjusted. If no adjustment of the shutter position is required during a clockwise adjustment of the valve, the valve can simply be adjusted to the desired position. 
     A position error to the valve introduced by the adjustment of the AGS system is minimized by increasing the ratio between the worm gear  1  and the valve member  3 . That is, a higher ratio requires the worm  1  and the crank  5  to rotate much more than the valve member  3 . Thus, the AGS shutter  24  can be brought into position with minimal disturbance of the valve position. Also, the time required to achieve a desired AGS shutter position can be as high as several seconds without affecting temperatures. Therefore, the priority for position is valve position, with a follow up position control for the AGS shutters. 
     Because the OWC  6  is arranged between the crank  5  and the worm gear shaft  7 , there is no fixed relationship between the crank  5  and the worm gear shaft  7 . Therefore, it is desirable for the controller  25  to periodically determine a zero point, i.e., a fully closed point of the AGS shutter  24 . This determination may be accomplished using a latching mechanism  10  as shown in  FIGS. 3A and 3B , which includes a flat spring  11  with a tab  12  and a friction interface between the flat spring  11  and the crank  5 . The flat spring  11  is mounted so that is movable relative to a housing  8 . Motion of the flat spring  11  is limited to a linear translation relative to the housing  8  by mounts  19 . The friction interface may, for example, comprise a tab  13  resting with resilient force on the crank. A knob  14  on the crank  5  interfaces with tab  12  on the flat spring as follows. When the crank  5  rotates, the knob  14  strikes the tab  12  causing the flat spring  11  to move in the direction of arrow B in  FIG. 3A  until the spring contacts friction washer  15  and/or shaft  7 . This contact stops the linear motion of the flat spring  11  and the rotation of the motor. At this point, power drawn by the motor will peak as described above, and the reference position relating to a specific position of the AGS shutters, can be stored in the controller  25 . 
     As the flat spring  11  moves, a section of the flat spring  11  proximate the tab  12  slides up a ramp  16  and the tab  12  is raised relative to the knob  14 . However, friction between the knob  14  and the tab  12  prevents the tab from clearing the knob  14 . That is, even though the ramp pulls up on the tab  12 , torque produced by the motor urges the knob  14  against the tab  12  and the frictional force therebetween prevents the tab from clearing the knob  14  (see, e.g.,  FIG. 3B ). Once the reference point is recorded, the controller  25  turns off power to the motor momentarily, thereby removing the friction force between the tab  12  and the knob  14  and the tab  12  clears the knob  14 . 
     Further rotation of the motor rotates the crank  5  until the knob  14  contacts the tab  13 , pushing the flat spring  11  in the direction C (opposite the direction B) until the flat spring  11  returns to its original position. The AGS shutter position can be referenced in this way once per revolution of the crank  5 . The controller  25  may rotate the crank  5  through one or more cycles periodically to ensure a proper position of the shutter  24 . For example, the controller  25  may rotate the worm shaft  7  through one or more clockwise rotations after a predetermined period in which no adjustments are made to ensure that the shutter  24  is maintained in the proper position. After the one or more clockwise rotations, the shutter  24  is moved to the desired position and the shaft  7  is then rotated back to the desired position of the valve member  3  by counter clockwise revolutions. 
       FIG. 3C  shows a graph illustrating the shutter position and the torque during two revolutions of the crank. In the top part of the graph, the crank is rotated through two cycles from the closed position of the shutters to the open position of the shutters and back. The reference position is when the shutters are shut half way on the way to the closed position. The knob  14  first contacts the tab during rotation at point  30 ,  30 ′. Further rotation of the crank increases the torque required to move the crank until the spring motion stops when the flat spring  11  contacts the shaft  7  or the friction washer  15 , i.e., at positions  32 ,  32 ′. The controller  25  will then associate the position of the worm gear shaft  7  with a half closed position of the shutters at points  32 ,  32 ′. Instead of using the flat spring  11 , the latching mechanism may also be realized using a leaf spring or a coil spring. 
     The referencing function may be achieved in a variety of alternative ways. For example, an additional sensor  26  (see  FIG. 4 ) may be used to monitor the crank position instead of the latching system  10 . The sensor may, for example, be a rotary encoder or a hall effect sensor measuring rotation of the shaft  7  or a proximity sensor or infrared beam sensor monitoring a position of the crank  5 . 
     As an alternative to the OWC  6 , a solenoid and small clutch could be used to selectively connect the motor  4  to the valve member  3  or the crank  5 .  FIG. 5  schematically shows a solenoid SOL operatively connected to an output shaft of motor  4 . The output shaft is connected to a clutch  28  that is normally connected to the worm gear  1 . When the solenoid SOL is energized the clutch  28  connects the output shaft to the crank  5  so that the shutter  24  can be adjusted. This embodiment would avoid the small errors in the valve position discussed above. 
     The present invention has been described with reference to a preferred embodiment. It should be understood that the scope of the present invention is defined by the claims and is not intended to be limited to the specific embodiment disclosed herein. For example, elements of specific embodiments may be used with other embodiments without deviating from the scope of the present invention.