Patent Publication Number: US-2013247862-A1

Title: Grille shutter opening/closing control device

Description:
TECHNICAL FIELD 
     This invention relates to an opening/closing control device for a grille shutter which controls opening and closing of a grille opening provided at a front portion of a vehicle. 
     BACKGROUND OF THE TECHNOLOGY 
     In a vehicle, a grille opening is provided at a front face of the vehicle for introducing outside air to the front side of a radiator installed in an engine compartment of the vehicle. A grille shutter is provided at the grille opening for opening or closing the grille opening to allow or interrupt the introduction of the outside air into the engine compartment. As such conventional devices, the Patent Documents 1 and 2 disclose conventional technology for such devices. 
     DOCUMENT LIST OF STATE OF ART 
     Patent Document 
     Patent Document 1: JP2008-6855 A 
     Patent Document 2: JP1993-50861 A 
     DISCLOSURE OF INVENTION 
     Problems to be Solved 
     According to the above type grille shutter opening/closing device, the operation noise is generated when the fins of the shutter contact the frame of the opening at the closing ends thereof and the noise is transmitted to the frame of the vehicle which gives the occupant in the vehicle an unpleasant feeling. Particularly, such noise may annoy the occupant of the HV (Hybrid Vehicle) or an electric vehicle (EV) which generates a low running noise. 
     In order to reduce such operation noise, in a conventional device, a cushioning material was provided at the noise transmitting portion, such as fins of the shutter to block the noise transmission or the operation speed of the shutter was reduced to make a noise small as possible. However, according to the former structure, the manufacturing cost increases due to the addition of material and another issue arises that the deterioration with age of the cushioning material reduces the effect of noise blocking and according to the latter structure, due to insufficient torque, a gear biting in the operating device for opening and closing the grille shutter may not be disengaged. In any case above, a satisfactory result has not been achieved yet. 
     Accordingly, this invention was made considering the above conventional drawbacks and it pertains to a grille shutter opening/closing control device which can reduce an operation noise generated at the time of closing operation of the grille shutter without increasing any manufacturing cost. 
     Means for Solving the Problems 
     In order to solve the above problems the feature of the invention associated with claim  1  is characterized in that the grille shutter opening/closing control device is comprised of a grille shutter for opening and closing a grille opening through which the air is introduced into an engine compartment of a vehicle, a shutter opening/closing operating portion with a drive source for operating the grille shutter to open and close, a closing operation judging portion for judging whether the grille shutter is to be operated in a closing direction or not on an inputted vehicle information and a drive source torque controlling portion for controlling the drive source of the shutter opening/closing operating portion to operate the grille shutter first by a high torque and thereafter by a low torque which is lower than the high torque when the grille shutter is judged to be operated in the closing direction by the closing operation judging portion. 
     According to a feature of the invention associated with claim  2 , in claim  1 , the drive source torque controlling portion controls the drive source of the shutter opening/closing operating portion to operate the grille shutter until the grille shutter moves to a position before a set distance to the closing end of the shutter by the high torque. 
     Effects of the Invention 
     According to the invention of claim  1 , upon closing operation of the grille shutter, the drive source of the shutter opening/closing operating portion is controlled to operate the grille shutter first by a high torque and thereafter by a low torque which is lower than the high torque. Accordingly, the operation noise generated at the closing end of the grille shutter can be reduced and even when a gear biting is generated in the gear portion of the shutter opening/closing operating portion at the start of the operation, the grille shutter can be surely and stably closed by driving by a high torque at the start of operation. 
     According to the invention of claim  2 , the drive source torque controlling portion is controlled to operate the grille shutter to move to a position until before a set distance to the closing end of the grille shutter, in addition to the advantages of the invention of claim  1 , the closing speed of the shutter can be raised to shorten the closing time of the shutter. 
    
    
     
       BRIEF EXPLANATION OF ATTACHED DRAWINGS 
         FIG. 1  is a schematically illustrated cross sectional view of a grille shutter of an embodiment of the invention showing an assembled state into an engine compartment of a vehicle; 
         FIG. 2  shows an exploded perspective view of the grille shutter of the embodiment showing an overall structure; 
         FIG. 3  is a plane view of the grille shutter of the embodiment; 
         FIG. 4  is a view showing the grille shutter opening/closing operating portion; 
         FIG. 5  is a control block view for controlling the grille shutter opening/closing operating portion; 
         FIG. 6  is a flowchart for controlling the grille shutter opening/closing operation; and 
         FIG. 7  is a schematic view of the grille shutter according to another embodiment of the invention. 
     
    
    
     THE EMBODIMENTS FOR IMPLEMENTING THE INVENTION 
     The embodiments of the invention will be explained with reference to the attached drawings.  FIG. 1  shows a schematically illustrated grille shutter of an embodiment of the invention showing an assembled state into an engine compartment  2  of a vehicle. A radiator  3  is housed in the engine compartment for cooling the coolant of the engine and is attached to a vehicle body  4 . A grille opening  6  is provided at a lower side of the vehicle body under a bumper  5 . The opening  6  faces to the front side at lower portion of the radiator  3 . A grille shutter  1  is provided in the opening  6  for opening and closing the grille opening  6 . 
     As shown in  FIG. 2 , the grille shutter  1  is provided with a base frame  7  arranged at the grille opening  6 , a plurality of fins  11  through  14  (in this embodiment, the number of fins is four) and an actuator  15  as a shutter opening/closing portion with a motor  60  (see  FIG. 4 ) as a drive source. The base frame  7  is formed to be of an elongated shape extending in a vehicle width direction and a central portion  7   a  thereof in the extending direction is most closely positioned in a vehicle front side direction. Both sides  7   b  and  7   c  of the base frame  7  in the extending direction are bent to be off-set in a vehicle rear side direction from the position of the central portion  7   a.  An actuator attaching portion  16  is provided at the central portion  7   a  for attaching the actuator  15  therein. A plurality of fin attaching portions  17  through  20  corresponding to the first fin  11 , the second fin  12 , the third fin  13  and the fourth fin  14  is provided at both sides in the vehicle width direction relative to the actuator attaching portion  16 . The fin attaching portions  17  through  20  are arranged at the both sides, each of the two portions  17 ,  19 ;  18 ,  20  being in parallel to each other in an up/down direction. 
     The first fin  11  includes a first supporting linear shaft  21  extending in a vehicle width direction and a fin portion  11   a  integrally formed with the first linear shaft  21 . Similarly, the second fin  12  includes a second supporting linear shaft  22  extending in a vehicle width direction and a fin portion  12   a  integrally formed with the second linear shaft  22 , the third fin  13  includes a third supporting linear shaft  23  and a fin portion  13   a  integrally formed with the third linear shaft  23  and the fourth fin  14  includes a fourth supporting linear shaft  24  and a fin portion  14   a  integrally formed with the fourth linear shaft  24 , respectively. 
     One end portion  7   b  in a vehicle width direction (right side as viewed in  FIG. 2 ) of the base frame  7  is provided with a first holding portion  25  for holding the first supporting shaft  21  of the first fin  11  and a third holding portion  26  for holding the third supporting shaft  23  of the third fin  13 . The other end portion  7   c  in a vehicle width direction (left side as viewed in  FIG. 2 ) of the base member  7  is provided with a second holding portion  27  for holding the second supporting shaft  22  of the second fin  12  and a fourth holding portion  28  for holding the fourth supporting shaft  24  of the fourth fin  14 . A first output shaft  32  and a third output shaft  33  are provided at a right side surface  31  of the actuator  15  and a second output shaft  35  and a fourth output shaft  36  are provided at a left side surface  34  of the actuator  15 . 
     One tip end  41  of the first supporting shaft  21  of the first fin  11  is rotatably supported on the first holding portion  25  and the other tip end  42  of the first supporting shaft  21  is rotatably connected to the first output shaft  32  as viewed in  FIG. 3 . Similarly, one tip end  43  of the second supporting shaft  22  of the second fin  12  is rotatably supported on the second holding portion  27  and the other tip end  44  of the second supporting shaft  22  is rotatably connected to the second output shaft  35 , the one tip end  45  of the third supporting shaft  23  of the third fin  13  is rotatably held on the second holding portion  26  and the other tip end  46  is rotatably connected to the third output shaft  33  and the one tip end  47  of the fourth supporting shaft  24  is rotatably held on the fourth holding portion  28  and the other tip end  48  is rotatably connected to fourth output shaft  36 . The first and the second fins  11  and  12  are arranged with the third and the fourth fins  13  and  14  facing to one another and operated to open/close symmetrically relative thereto (see two dotted chain lines  8 A and  8 B in  FIG. 1 ). 
     As shown in  FIG. 4 , the actuator  15  is provided with a housing  71  and a motor  60  as the drive source is housed in the housing  71 . An output shaft of the motor  60  is connected with a worm gear  61  which is in engagement with a worm wheel  62 . A first pinion gear  63  is integrally and coaxially formed with the worm gear  62 . The first pinion gear  63  is engaged with a gear  64  and a second pinion gear  65  is integrally and coaxially formed with the gear  64 . The second pinion gear  65  is engaged with a sector gear  66 . A second output gear  67  is integrally and coaxially formed with the sector gear  66  and a first output gear  68  is engaged with the second output gear  67  at an upper portion of the second output gear  67 . 
     When the motor  60  thus structured is rotated forwardly and reversely, the second output gear  67  is rotated in one direction through the worm gear  61 , worm wheel  6 , first pinion gear  63 , gear  64 , second pinion gear  65  and sector gear  66  and at the same time the first output gear  68  is rotated in the opposite direction to the second output gear  67  through the second output gear  67 . 
     The first and the second output gears  68  and  67  are provided with one pair each in the rotation shaft direction relative to the worm wheel  62 , gear  64  and the sector gear  66 . The each of the pair of first output gears  68  is connected to the first and the second output shafts  32  and  35 , respectively. Each tip end of the first and the second output shafts  32  and  35  is provided with a projection  54  with a width across flat, respectively and each tip end of the third and the fourth output shafts  33  and  36  is provided with a projection  69  with a width across flat, respectively. 
     The projections  54  with width across flats formed on the first and the second output shafts  32  and  35  are not shown in the attached drawings, but these projections  54  are to be engaged with recessed portions formed at the other tip ends  42  and  44  of the first and the second supporting shafts  21  and  22  of the first and the second fins  11  and  12  thereby rotatably connecting the first and the second output shafts  32  and  35  with the first and the second supporting shafts  21  and  22 . Similarly, the projections  69  with the width across flats formed on the third and the fourth output shafts  33  and  36  are to be engaged with recessed portions formed at the other tip ends  46  and  48  of the third and the fourth supporting shafts  23  and  24  of the third and the fourth fins  13  and  14  thereby rotatably connecting the third and the fourth output shafts  33  and  36  with the fourth supporting shafts  23  and  24 . 
     According to thus structured embodiment, each first output gear  68  and each second output gear  67  are rotated oppositely to each other by the motor  60  of the actuator  15 . Therefore, the supporting shafts  21  and  22  of the first and the second fins  11  and  12  are rotated oppositely with the rotation of the supporting shafts  23  and  24  of the third and the fourth fins  13  and  14  to open or close the grille opening  6  by the operation of the grille shutter  1 . When the grille shutter  1  is under closing operation, the grille opening  6  is closed by the contact of the fins  11  through  14  with the each end surface  7   d  and  7   e  of the base frame  7  (see  FIG. 1 ). Accordingly, if the speed of the closing operation of the fins  11  through  14 , an operation noise may be generated. 
     The shutter opening/closing operating portion (actuator  15 ) id formed by the above motor  60 , worm gear  61 , worm wheel  62 , first pinion gear  63 , gear  64 , second pinion gear  65 , sector gear  66 , second output gear  67  and first output gear  68 . 
       FIG. 5  shows a control device  80  which controls the operation of the shutter opening/closing operating portion  15 . The control device  80  includes CPU  81 , ROM  82 , RAM  83  and the bus line  84  which connects the components of the control device. An input/output interface  85  is connected to the bus line  84 . The input/output interface  85  is connected to a motor control circuit  86  for controlling the motor  60  and a position sensor  87  for detecting the rotation position (corresponding to the rotation angle of the motor  60 ) of the grille shutter  1 . Further, the vehicle information, such as vehicle speed, water temperature of the radiator  3 , engine (EG) operation state and hybrid motor (HV motor) operation state is inputted to the input/output interface  85  through communication circuit  88 . 
     In the ROM  82 , a program for opening and closing the grille shutter  1  is stored and a set value for setting a rotational position where the grille shutter  1  is changed from the high torque operation to the low torque operation when the shutter  1  is inclosing operation is memorized in the ROM  82 . Further, in the ROM  82 , a high torque set value set in advance for driving the motor  60  of the shutter opening/closing operating portion  15  by a high torque and a low torque set value set in advance for driving the motor  60  by a low torque are memorized. It is noted here that the low torque set value is set to be a noise level so that the operation noise generated by the contact of the fins  11  through  14  with the end surfaces  7   d  and  7   e  upon closing operation of the grille shutter  1  by the motor  60  by the low torque set value may not make the driver of the vehicle feel unpleasant. 
     In the RAM  83 , the inputted vehicle speed is memorized and the position information detected by the position sensor  87  is also memorized. Based on the position information, the state of the grille shutter  1  is judged whether the shutter is in fully closed state or in fully opened state. 
     An operation of the embodiment explained above will be explained based on the flowchart in  FIG. 6 . In normal condition, the grille opening  6  is opened. Under this normal state, the rise of temperature of the engine coolant is suppressed by introducing the air into the engine compartment  2  through the grille opening  6  on to the front surface of the radiator  3 . 
     The flowchart in  FIG. 6  is started by the engine ignition being turned ON. At step  100 , the vehicle information, such as the vehicle speed, ambient temperature, temperature of coolant in the radiator  3  and the engine (EG) operation state is inputted and at the next step  102 , it is judged whether the opening/closing operation condition of the grille shutter  1  is established or not based on the inputted vehicle information. 
     For example, when the temperature of the coolant in the radiator  3  is below the set temperature and the radiator is not necessary to be further cooled down or when the engine is operated and the ambient temperature and the temperature of the radiator are both below the set values, under such conditions, the engine temperature should be raised promptly, the shutter closing condition is judged to be established. Vice versa, if the temperature of the coolant in the radiator  3  exceeds the set value, the shutter opening condition is judged to be established. At the step  102 , if the condition is established and the judgment result is “YES”, at the step  104 , whether the grille shutter  1  is to be closed (closing operation of the shutter  1 ) or to be opened is judged. If the result is “YES (Closing)”, at the next step  106 , the motor  60  of the shutter opening/closing operating portion  15  is driven by a high torque value set in advance to operate the grille shutter  1  by a high torque (high speed operation) so that the fins  11  through  14  of the grille shutter  1  are respectively rotated about the respective supporting shafts  21  through  24  with a high speed. 
     Next at the step  108 , it is judged whether or not the grille shutter  1  is operated to be moved to a position before a set distance to the closing end of the grille shutter  1  based on the detection signal of the position sensor  87  and If the judgment result is “YES”, at the next step  110 , the motor  60  of the shutter opening/closing operating portion  15  is switched over to be driven by a low torque value set in advance to operate the grille shutter  1  by a low torque (low speed operation) so that the fins  11  through  14  of the grille shutter  1  are respectively rotated about the respective supporting shafts  21  through  24  with a low speed. 
     On the other hand, at the step  104 , if the judgment result is “NO” (open operation), the program goes to the step  112 . At the step  112 , the motor  60  of the shutter opening/closing operating portion  15  is driven by a high torque value set in advance to operate the grille shutter  1  by a high torque (high speed operation) so that the fins  11  through  14  of the grille shutter  1  are respectively rotated about the respective supporting shafts  21  through  24  with a high speed. In other words, when the grille not in contact with the base frame  7  and accordingly, no issue is raised since there is no operation noise generated when the grille shutter  1  is opened with a high speed. 
     At each step  110  and  112 , when the grille shutter  1  is operated by a low torque or a high torque, the program goes to the next step  114  or  116 . At the step  114  or  116 , whether the grille opening  6  is fully opened or fully closed by the grille shutter  1  is judged based on the detecting signal from the position sensor  87 . If the judgment result is “YES”, the motor  60  is stopped at the step  118  and if the result is “NO” at the step  114  or  116 , the program goes back to the step  110  or  112  to repeat the operation until the grille opening  6  is fully closed or fully opened. 
     On the other hand, under the state that the grille opening  6  is closed, when the temperature of coolant in the radiator  3  rises to or exceeds a preset temperature degree, at the step  102  the condition of opening/closing operation (here, opening operation) of the shutter  1  is judged to be established and the judgment result at the next step  104  becomes “NO”. Then the program goes to the step  112  to start opening operation (high speed operation) of the grille shutter  1 . 
     The closing operation judging portion is formed by the judging step  104  in which whether the grille shutter  1  should be operated in a closing direction or not based on the vehicle information is judged. The motor torque controlling portion is formed by the steps  106 ,  108  and  110  in which the motor  60  (drive source) of the actuator  15  (shutter opening/closing operating portion) is controlled to operate the grille shutter  1  to perform closing operation first by a high torque and thereafter by a low torque lower than the high torque in the closing direction. 
     According to the embodiment of the invention, when the grille shutter is operated in a closing direction, the motor  60  of the shutter opening/closing operating portion  15  is controlled to operate the grille shutter  1  to perform closing operation by a high torque until the grille shutter  1  is moved to a position before a set distance to the closing end thereof and thereafter by a low torque which is lower than the high torque. Accordingly, the operating noise generated at the closing ends of the shutter  1  can be reduced without adding cushioning material i.e., without increasing the manufacturing cost and without giving a driver of the vehicle an unpleasant feeling. Further, at the beginning of closing operation, the shutter is operated by a high torque and accordingly, even if any gear biting trouble should occur, the grille shutter  1  can be surely and stably closed. In addition, since the grille shutter  1  is operated by a high torque, the closing speed of the shutter is raised and the time for closing operation of the shutter can be shortened. 
       FIG. 7  shows another embodiment of the invention. The grille shutter  1  for opening and closing the grille opening  6  is formed by a plurality of (four in the embodiment in  FIG. 8 ) fins  111  through  114  each of which can be in contact with another in up-down direction. Each fin  111  through  114  has a supporting shaft  121  through  124  at the center thereof and the fins are rotatable about the shafts. Each supporting shaft  121  through  124  is connected to each one end of link members  91  through  94 . The link members  91  through  94  are connected to a link operating mechanism  95  with a motor as a drive source. The fins  111  through  114  are rotated together with the link members  91  through  94  by the link operating mechanism  95  thereby to open and close the grille opening  6 . 
     An operating noise is generated by the structure of this modified embodiment. The operating noise is caused by the contact of the each end portion of the fins  111  through  114  to close the grille opening  6  upon closing operation of the grille shutter  1 . Accordingly, the application of the invention is not limited to the structure shown in  FIGS. 1 and 2 , but the invention can be applied to such structure of the grille shutter  1  other than the structure of the grille shutter  1  shown in  FIGS. 1 and 2 . 
     According to the embodiments of the invention explained above, the grille shutter  1  is opened and closed by a high torque or a low torque. However, the grille shutter  1  may be opened and closed with a high speed or a low speed thereby to change the opening or closing torque. Accordingly, the invention includes the motor torque controlling portion for controlling the shutter with a high speed or a low speed. 
     Further, according to the embodiments explained above, the grille opening  6  is fully opened or fully closed by the grille shutter  1  based on the vehicle information. However, an opening degree of the grille opening  6  may be controlled based on the vehicle speed. For example, if a vehicle is running with a high speed, since the amount of air introduced into the engine compartment is greater than the state that vehicle running with a low speed or a medium speed, a sufficient air flow can be ensured even the area of opening is small. For this reason, by controlling to lessen the opening degree of the grille opening  6 , the air resistance can be reduced to thereby improve the fuel efficiency. 
     On the other hand, according to the embodiment, the motor  60  is used as the drive source of the shutter opening/closing operating portion  15 . In addition to the motor, a mechanism for opening and closing the grille shutter  1  by a biasing member such as a spring may be used. Further, in addition to the motor, a vacuum actuator utilizing the intake vacuum of the engine or a hydraulic actuator utilizing the operation fluid used in the engine or a transmission of the vehicle may be used in combination with the motor to control opening and closing of the grille shutter  1 . 
     The embodiments of the invention are explained hitherto, however, the invention is not limited to the explained embodiments but other modifications or alterations of the embodiments can be included in the invention within the subject matter of the invention. 
     INDUSTRIAL APPLICABILITY OF THE INVENTION 
     The grille shutter opening/closing control device of this invention is applicable to a vehicle with engine, or a hybrid vehicle with engine and hybrid motor having a grille shutter for opening and closing a grille opening provided at a front portion of the vehicle. 
     EXPLANATION OF REFERENCE NUMERALS 
     In the drawings:  1 : grille shutter,  2 : engine compartment,  3 : radiator,  6 : grille opening,  11 - 14 : fins,  15 : shutter opening/closing operating portion (actuator),  60 : motor (drive source),  80 : control device,  104 : closing operation judging portion,  106 ,  108 ,  110 : motor torque controlling portion (drive source torque controlling portion)