Patent Publication Number: US-8543297-B2

Title: Method of limiting a closing force of a motorized opening

Description:
REFERENCE TO RELATED APPLICATION 
     This application claims priority to French Patent Application No. 0804806 filed Sep. 2, 2008. 
     BACKGROUND OF THE INVENTION 
     The present invention relates to a method of limiting a closing force of a motorized opening on a sealing line of a motor vehicle, such as a window regulator window in a door seal, an opening/tilting roof, a motorized sliding side door, or a motorized swinging door (tailgate or trunk lid), etc. 
     In particular, a motorized window regulator makes it possible to open or close, by a window, an opening situated in a motor vehicle door. While the window is closing, a top edge of the window penetrates, for example, into a seal situated at a top of an opening of the door. 
     The force needed to raise the window in a door frame, called a transfer force, is roughly constant before the top edge of the window reaches the seal. 
     An additional force, called a closing force, is the force added to the transfer force to enable the top part of the window to penetrate into the seal in order to completely close the window, then to enable the seal to be squashed by the top edge of the window in order to ensure air and water tightness. The sum of the transfer force and the closing force is called a total force. 
     When the seal is squashed so that its reaction force no longer allows the window to advance, the window is subjected to a so-called blocking force. It is then at a top mechanical end stop. 
     However, the blocking force depends on the power supply voltage to the window regulator&#39;s electric motor. Thus, if the window is closed when the motor of the motor vehicle is switched off, the window has reached a mechanical end stop position. If the power supply voltage to the window regulator&#39;s electric motor is increased, for example when the engine of the motor vehicle is running, the blocking force increases. Now, because the window is in a mechanical end stop position, the increase in voltage is translated into an increase in the mechanical stresses on the components of the window regulator located between the window regulator&#39;s electric motor and the window, such as, for example, the sliders, and, for a cable-operated window regulator, the pulleys, the drum and the cables. This excess blocking force provides no additional benefit in the sealing process and unnecessarily limits the life of the window regulator. It is therefore advantageous to limit the closing force in order to increase the life of the window regulator. 
     The document U.S. Pat. No. 6,208,101 proposes a method for limiting surplus force of an electronically controlled window regulator when a top edge of a window abuts against a seal. This method includes the continuous detection of the positions of the window during the displacement of the window. This method also includes the recording of at least one measured value. This measured value is correlated with a total force applied to the window after a top edge of the window has entered to a depth of at least 25% of a seal area. The measured value is increased by a predetermined quantity to define a stop criterion so that the window regulator is stopped when this criterion is reached or exceeded. The stop criterion is therefore generated on the basis of at least one quantity measured after the top edge of the window has penetrated into the seal. 
     One drawback of this method is that the stop criterion depends on the total force applied to the window in the seal. In very cold weather, the total force applied to the window in the seal is very great. The closing force will not therefore be limited, or will be limited only very little in very cold weather, which means that the mechanical stresses on the components of the window regulator cannot be avoided. 
     There is therefore a need to limit the closing force regardless of the climatic or operating conditions of the motor vehicle. 
     SUMMARY OF THE INVENTION 
     The invention provides a method of limiting a closing force of a motorized opening on a sealing line of a motor vehicle. A driving system for the motorized opening includes an electric motor driving the opening having an edge. The method includes the step of calculating a closing force at each instant in a displacement of the opening while closing. The closing force is calculated by a difference between a total force applied to the opening when the edge of the opening is situated in an area of the sealing line or squashes the sealing line and the transfer force applied to the opening just before the edge of the opening penetrates into the area of the sealing line or squashes the sealing line. The method also includes the step of stopping the electric motor driving the opening when the closing force reaches a predetermined value, the predetermined value being a constant. 
     According to another particular feature, the method also includes the step of determining the force applied to the opening at each instant. According to another particular feature, the total force and the transfer force are determined according to a speed of the electric motor and a voltage applied to the electric motor. According to another particular feature, the method also includes the step of continually measuring a position of the opening. According to another particular feature, the step of stopping the electric motor includes recording the position of the opening at the moment of stopping the electric motor, called a software closing position. According to another particular feature, when the opening is actuated to be closed when the edge of the opening is situated in the area of the sealing line or squashes the sealing line, the opening is positioned in the software closing position recorded last. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Other characteristics and benefits of the invention will become apparent from the following detailed description of the embodiments of the invention, given purely by way of example and with reference to the drawings, which show: 
         FIG. 1  illustrates a curve representing a force applied to a window of a motorized window regulator according to a position of the window; 
         FIG. 2  illustrates a curve representing a speed of the window regulator&#39;s electric motor according to the force applied to the window in the event of a voltage fluctuation; 
         FIG. 3  illustrates a curve representing the speed of the window regulator&#39;s electric motor according to the force applied to the window in the event of a temperature fluctuation; 
         FIG. 4  illustrates a vehicle door; and 
         FIG. 5  illustrates a vehicle. 
     
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
     The invention relates to a method of limiting a closing force of a motorized opening  12  on a sealing line of a motor vehicle  90  (shown in  FIG. 5 ). As shown in  FIG. 4 , a driving system for the opening  12  includes an electric motor  20  driving the opening  12 , and the opening  12  includes an edge. The method includes the step of calculating a closing force at each instant in a displacement of the opening  12  while closing and the step of stopping the electric motor  20  driving the opening  12  when the closing force reaches a predetermined value. The closing force is calculated by the difference between a total force applied to the opening  12  when the edge of the opening  12  is situated in an area of the sealing line or squashes the sealing line and a transfer force applied to the opening  12  just before the edge of the opening  12  penetrates into the area of the sealing line or squashes the sealing line. The predetermined value is a constant. 
     The closing force according to the invention does not depend on the transfer force, unlike the method of U.S. Pat. No. 6,209,101. The closing force is a constant. Thus, the closing force does not depend on the climatic or operating conditions of the motor vehicle  90 . The closing force is therefore well limited regardless of the climatic conditions or the operating conditions of the motor vehicle  90 . The seal area is the area situated inside a seal  16 , delimited by two sides of the seal  16  and a bottom of the seal  16 . 
     Hereinafter in the description, the motorized opening  12  described as an example will be a motorized window regulator window  10 . However, the invention also relates to other motor vehicle motorized openings  12 , such as an opening/tilting roof, a motorized sliding side door, a motorized swinging door (tailgate or trunk lid), etc. Thus, the description of the window  10  and of the window regulator  22  should not be taken to be limiting. 
     The sealing line associated with the window  10  is a seal  16  including two edges and a bottom. In other cases, such as for a motorized swinging door, for example, the sealing line is, for example, a seal  16  of cylindrical section. Hereinafter in the description, only a seal  16  including two edges and a bottom will be described, in a nonlimiting manner. 
       FIG. 1  shows a curve representing a force applied to a window  10  of a motorized window regulator  22  according to a position of the window  10 . The curve is plotted for a given temperature. 
     A window regulator  22  includes an electric motor  20  suitable for a window  10  being raised or lowered. In one example, the window  10  is used to close an opening  12  formed in a motor vehicle door  18 . In this case, the window  10  includes a top edge  14  adapted to penetrate into a seal  16  situated at a top of the opening  12  formed in a door  18  of a motor vehicle  90 . However, the invention also relates to the windows  10  actuated by motorized window regulators  22  in doors  18  without a frame. In this case, the top edge  14  of the window  10  penetrates into a seal  16  situated in a roof of the motor vehicle  90 . 
     The electric motor  20  of the window regulator  22  applies a force to the window  10  via different components of the window regulator  22 , such as, for example, in the case of a cable-operated window regulator, pulleys, sliders, etc. This force enables the window  10  to be raised or lowered in order to release or close the opening  12  formed in the door  18  of the motor vehicle  90 . 
     The force applied to the window  10  by the electric motor  20  is directly correlated to the operating conditions of the electric motor  20 . Thus, in the method of limiting the closing force, the force applied to the window  10  by the electric motor  20  is determined according to a speed of the electric motor and a voltage applied to the electric motor  20 . The force is therefore determined simply by direct correlation with the window regulator&#39;s  22  electric motor  20 . 
     The force applied to the window  10  is determined at each instant while the window regulator  22  is operating. Thus, the value of the force is available at each instant. This makes it possible to select force values that are of interest for the method, in particular, the value of the force applied to the window  10  just before the top edge  14  of the window  10  penetrates into the seal area and the value of the force applied to the window  10  when the top edge  14  of the window  10  is in the seal area or squashes the seal  16 . 
     The method of limiting the closing force also includes the step of continually measuring the position of the window  10 . Thus, the position of the window  10  is also known at each instant. This also makes it possible to select force values that are of interest for the method, in particular the value of the force applied to the window  10  just before the top edge  14  of the window  10  penetrates into the seal area and the value of the force applied to the window  10  when the top edge  14  of the window  10  is in the seal area or squashes the seal  16 . Thus, the speed can be determined according to the force, as represented in  FIGS. 2 and 3 , by derivation of the position. 
     In  FIG. 1 , the window begins to rise toward the door seal  16  at the point O. The window is subject to a transfer force, which enables the window  10  to rise before it reaches the seal  16 . As  FIG. 1  shows, the transfer force is substantially constant. Between the points O and A, the window  10  is at least partially open. 
     At the point A, the top edge  14  of the window  10  reaches the seal  16 . Between the points A and B, the top edge  14  of the window  10  is in the seal area. The penetration of the top edge  14  of the window  10  into the seal area makes it possible to completely close the opening  12  formed in the door  18  of the motor vehicle  90 , but without ensuring its seal-tightness. As  FIG. 1  shows, the force applied to the window  10  for the window to be able to penetrate into the seal area, called a penetration force, increases relative to the transfer force to overcome the friction forces against the sides of the seal  16 . 
     At the point B, the top edge  14  of the window  10  reaches the bottom of the seal  16 . As  FIG. 1  shows, the force applied to the window  10  for the window to be able to compress the seal  16 , called a squashing force, is even higher than the penetration force. This makes it possible to ensure the seal-tightness of the opening  12  formed in the door  18  of the motor vehicle  90 . However, a non-zero minimum squashing force is necessary to ensure the seal-tightness of the opening  12 . 
     The limiting method includes the step of calculating the closing force at each instant while the window  10  is rising. The closing force is calculated by the difference between the force applied to the window  10  when the top edge  14  of the window  10  is situated in the seal area or squashes the seal  16 , called a total force, and the transfer force Ft. 
     When the closing force reaches a predetermined value Ff, the window regulator&#39;s  22  electric motor  20  is stopped. The predetermined value Ff is a constant. This constant is supplied by the user of the method, for example by an automobile manufacturer. This predetermined value is preferably sufficient for the opening  12  formed in the door  18  of the motor vehicle  90  to be completely closed and air-tight and water-tight. The predetermined value Ff generally corresponds to the minimum closing force defined by the user of the method. Thus, the closing force does not depend on climatic conditions or on the operating conditions of the motor vehicle  90 , as will be seen later with  FIGS. 2 and 3 . 
     The total force on stopping the electric motor  20 , when the closing force reaches the predetermined value Ff, is the sum of the transfer force Ft and the predetermined value Ff. The total force when the electric motor  20  is stopped is called a software top end stop force Fbhl, or even a software closing force. The software top end stop force Fbhl is less than the blocking force Fb at the usual voltages (see Figures). The blocking force is the force applied to the window  10  when the window  10  is in a mechanical end stop position, that is to say, when the seal  16  is squashed by the top edge  14  of the window  10 , so that the reaction force of the seal  16  no longer allows the window  10  to advance. When the software top end stop force Fbhl is applied to the window  10 , the window  10  is in the software top end stop position or else in the software closure position. 
     At the point C of  FIG. 1 , the window  10  is in the software top end stop position. The software top end stop position is below the mechanical end stop position; Fbhl is less than Fb 1  or Fb 2 . Fb 1  and Fb 2  are blocking forces for two different voltages. Fb 1  corresponds, for example, to a voltage applied to the window regulator&#39;s  22  electric motor  20  of 14V and Fb 2  corresponds, for example, to a voltage applied to the window regulator&#39;s  22  electric motor  20  of 16V. Thus, in the sealing area, the locking force increases very rapidly while the top edge  14  of the window  10  progresses only very little into the seal  16 . This is why it is important to limit the closing force in order to increase the life of the window regulator  22 . 
     In the event of an increase in the power supply voltage to the electric motor  20 , for example when the engine of the motor vehicle  90  is running, the method of limiting the closing force makes it possible to avoid the mechanical stresses on the components of the window regulator  22  located between the electric motor  20  of the window regulator  22  and the window  10 , such as, for example, the sliders, pulleys, drum for a cable-operated window regulator  22 . Thus, if the window  10  had been closed when the engine of the motor vehicle  90  was switched off, the window  10  has reached a software top end stop position. In the event of an increase in the power supply voltage to the window regulator&#39;s  22  electric motor  20 , for example if a user once again orders the window  10  to rise when the engine of the motor vehicle  90  is running, the window  10  will remain in the software top end stop position and therefore not lead to additional stresses on the elements of the window regulator  22 . 
       FIG. 2  shows a curve representing the speed of the window regulator&#39;s  22  electric motor  20  according to the force applied to the window  10  in the event of a fluctuation in the power supply voltage to the electric motor  20 . 
     Two different power supply voltages U 1  and U 2  for the electric motor  20 , U 2  being greater than U 1 , give different corresponding transfer speeds S 1  and S 2 . In particular, the higher the power supply voltage becomes, the faster the speed becomes. On the other hand, the transfer force Ft does not vary with the power supply voltage to the electric motor  20 . Thus, the software top end stop force, which is the sum of the transfer force Ft and of the predetermined closing force value Ff, does not vary with the power supply voltage. As can be seen in  FIG. 2 , the blocking force Fb increases with the power supply voltage to the window regulator&#39;s  22  electric motor  20 , but not the software top end stop force Fbhl. 
       FIG. 3  represents a curve representing the speed of the window regulator&#39;s  22  electric motor  20  according to the force applied to the window  10  in the event of a fluctuation in temperature. 
     For an electric motor  20  power supply voltage U, two temperatures T 1  and T 2 , T 1  being greater than T 2 , lead to different corresponding transfer speeds S T1  and S T2  and different transfer forces Ft T1  and Ft T2 . In particular, the lower the temperature becomes, the lower the speed becomes and the more the transfer force Ft increases. The software top end stop force, which is the sum of the transfer force Ft and of the predetermined closing force value Ff, increases when the temperature drops. However, as can be seen in  FIG. 3 , the software top end stop force Fbhl T2  for the highest temperature remains very much less than the blocking force Fb. This makes it possible to avoid the mechanical stresses on the components of the window regulator  22  located between the window regulator&#39;s  22  electric motor  20  and the window  10 . 
     In practice, the predetermined value Ff of the closing force is chosen so that it is both sufficient to ensure the seal-tightness of the opening  12  and not too great to allow the software top end stop force to still be less than the blocking force, regardless of the conditions, in particular temperature conditions. 
     Moreover, the position of the software top end stop is recorded each time the window regulator&#39;s  22  electric motor  20  is stopped according to the method of limiting the closing force. 
     The record of the position of the software top end stop is useful in particular when the window regulator  22  is actuated to raise the window  10  when the top edge  14  of the window  10  is already in the seal area or squashing the bottom of the seal  16 . 
     In practice, in this particular case, the closing force cannot be calculated since the transfer force is not known. When the window  10  is actuated to be closed when the top edge  14  of the window  10  is situated in the seal area or squashing the seal  16 , the window  10  is positioned in the software top position recorded last. 
     Obviously, the present invention is not limited to the examples and to the embodiment described and represented, but lends itself to numerous variants accessible to those skilled in the art. Thus, as mentioned hereinabove, the method of limiting a closing force applies equally to a motorized window regulator window and to a motorized opening/tilting roof, a motorized sliding side door, a motorized swinging door (tailgate or trunk lid), etc. 
     The foregoing description is only exemplary of the principles of the invention. Many modifications and variations are possible in light of the above teachings. It is, therefore, to be understood that within the scope of the appended claims, the invention may be practiced otherwise than using the example embodiments which have been specifically described. For that reason the following claims should be studied to determine the true scope and content of this invention.