An automotive door system includes a hinge supporting a door. A door check module interconnects to one of the vehicle and the door by a linkage assembly. An output shaft is connected to the linkage assembly and rotates relative to a door check module housing. The output shaft provides an output torque to check the door in a desired door position. A sensor detects rotation of the shaft and produces a signal in response thereto. A brake assembly includes a shaft member operatively connected to the output shaft. The brake assembly has a normally closed position in which the shaft member is grounded to the housing in a door check mode. The brake assembly includes an open position that corresponds to one of a door closing mode and a door opening mode. The brake assembly moves from the normally closed position to the open position in response to the signal.

BACKGROUND 
       [0001]    This disclosure relates to a door check for a vehicle door, and more particularly, for a vehicle passenger door. 
         [0002]    Passenger doors are conventionally held opened and closed using a door check. A passenger pushes a button or engages a handle, which unlatches the door enabling it to swing open. The door check is interconnected between the frame and door and includes detents that define discrete door open positions, which hold the door open. When the door is opened or closed the holding force of the detent is overcome. 
         [0003]    A conventional door check only provides a few discrete door hold open positions that may not coincide with the most convenient door open angle for the passenger to ingress or egress the vehicle. Passive infinite door checks solutions such as U.S. Pat. No. 5,410,777 have been proposed to address this shortcoming. However even such a device can provide an inconsistent feel when the holding force of the detent is “released” depending on the attitude of the vehicle. For example, if the vehicle is parked on an incline, when released from a hold position, the door may feel as if it may suddenly close due to the weight of the door. A further shortcoming of the prior art is that door checks cannot be used to prevent the door hitting an obstacle when the door is swung open in a tight parking situation, which is desirable to prevent costly repair to the door. 
       SUMMARY 
       [0004]    In one exemplary embodiment, an automotive door system includes a hinge that is configured to support a door. A door check module is configured to be interconnected to one of the vehicle and the door by a linkage assembly. The door check module includes a housing. An output shaft is connected to the linkage assembly and configured to be rotatable relative to the housing. The output shaft is configured to provide an output torque to check the door in a desired door position. A sensor is configured to detect rotation of the shaft and produce a signal in response to the detected rotation. A brake assembly includes a shaft member that is operatively connected to the output shaft. The brake assembly has a normally closed position in which the shaft member is grounded to the housing in a door check mode. The brake assembly includes an open position that corresponds to one of a door closing mode and a door opening mode. The brake assembly is configured to move from the normally closed position to the open position in response to the signal. 
         [0005]    In a further embodiment of the above, a controller is in communication with the sensor and the brake assembly. The controller is configured to command the brake assembly to move from the normally closed position and release the shaft in response to the signal. The signal is indicative of slippage of the shaft member in the normally closed position. The controller is configured to command the brake assembly to the normally closed position in response to the signal falling below a threshold value and provide a holding torque in the desired door position. 
         [0006]    In a further embodiment of any of the above, an obstacle sensor is in communication with the controller. The obstacle sensor is configured to detect an obstacle, and the controller commands the door to stop with the brake assembly in the normally closed position in response to the detected obstacle. 
         [0007]    In a further embodiment of any of the above, a gearbox interconnects the output shaft and the shaft member. The gearbox multiplies the holding torque. 
         [0008]    In a further embodiment of any of the above, the brake assembly is arranged between the gearbox and the sensor. 
         [0009]    In a further embodiment of any of the above, the linkage assembly is configured to be interconnected to a door pillar and to transmit the output torque to the door pillar. 
         [0010]    In a further embodiment of any of the above, the position sensor is integrated with the brake assembly. The position sensor is configured to detect rotation of the shaft member, which is indicative of rotation of the output shaft. 
         [0011]    In a further embodiment of any of the above, the brake assembly includes a permanent magnet grounding the shaft member to the housing in the normally closed position. A coil is configured to overcome a magnetic flux of the permanent magnet to provide an open position that permits the shaft member to freely rotate relative to the housing. 
         [0012]    In a further embodiment of any of the above, the coil is modulated to provide a desired release of the brake assembly corresponding to a desired door feel. 
         [0013]    In a further embodiment of any of the above, the brake assembly includes a holding torque in the normally closed position, and the coil is configured to be modulated to decay the holding torque in relation to a pulse width modulation average voltage supplied to the coil. 
         [0014]    In a further embodiment of any of the above, the controller is configured to reverse a polarity of current to the coil to supplement the magnetic flux in the normally closed position and is configured to increase the door arresting torque. 
         [0015]    In a further embodiment of any of the above, an attitude sensor is in communication with the controller. The attitude sensor is configured to provide an attitude of the vehicle. The controller is configured to regulate the brake assembly in response to a signal from the attitude sensor. 
         [0016]    In another exemplary embodiment, an infinite door check includes a housing. An output shaft is configured to be rotatable relative to the housing. The output shaft is configured to provide an output torque to check a door in a desired door position. A sensor is configured to detect rotation of the shaft and produce a signal in response to the detected rotation. A brake assembly includes a shaft member operatively connected to the output shaft. The brake assembly has a normally closed position in which the shaft member is grounded to the housing in a door check mode. The brake assembly includes an open position that corresponds to one of a door closing mode and a door opening mode. The brake assembly is configured to move from the normally closed position to the open position in response to the signal. The signal is indicative of slippage of the shaft member in the normally closed position. 
         [0017]    In a further embodiment of any of the above, a gearbox interconnects the output shaft and the shaft member. The gearbox multiplies the holding torque. 
         [0018]    In a further embodiment of any of the above, a linkage assembly interconnects to the output shaft. The linkage assembly is configured to transmit the output torque from the output shaft to a door pillar. 
         [0019]    In a further embodiment of any of the above, the position sensor is integrated with the brake assembly. The position sensor is configured to detect rotation of the shaft member, which is indicative of rotation of the output shaft. 
         [0020]    In a further embodiment of any of the above, the brake assembly includes a permanent magnet that grounds the shaft member to the housing in the normally closed position. A coil is configured to overcome a magnetic flux of the permanent magnet to provide an open position that permits the shaft member to freely rotate relative to the housing. 
         [0021]    In a further embodiment of any of the above, a reverse polarity of current to the coil supplements the magnetic flux in the normally closed position and is configured to increase the door arresting torque. 
         [0022]    In another exemplary embodiment, a method of checking a door includes the steps of holding a door in an open position with an electric brake assembly and manually pivoting the door in a direction about a hinge to provide a manual input. The manual input is detected and the electric brake assembly is released in response to the manual input. 
         [0023]    In a further embodiment of any of the above, the detecting step includes back-driving a gearbox via an output shaft and detecting rotation of the output shaft. 
         [0024]    In a further embodiment of any of the above, the detecting step includes indirectly sensing rotation of the output shaft by sensing rotation of an electric brake assembly shaft member. 
         [0025]    In a further embodiment of any of the above, the manual input includes pushing or pulling on the door and exceeding a slip torque of a brake assembly that holds the door. The releasing step is performed in response to the slip torque. 
         [0026]    In a further embodiment of any of the above, the method includes the step of detecting a door obstacle. The door holding step is performed in response to the detected obstacle. 
         [0027]    In a further embodiment of any of the above, the door holding step includes reversing a polarity of current to a coil in the electric brake assembly to supplement the magnetic flux in a normally closed brake position and is configured to increase the door arresting torque. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0028]    The disclosure can be further understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein: 
           [0029]      FIG. 1A  is a perspective view of a vehicle door with an infinite door check mounted to a door pillar. 
           [0030]      FIG. 1B  is an enlarged perspective view of the door illustrating a linkage assembly of the infinite door check. 
           [0031]      FIG. 2  is a schematic view of an example door system embodiment that uses the infinite door check. 
           [0032]      FIG. 3A  is a perspective view of the infinite door check. 
           [0033]      FIG. 3B  is a cross-sectional view of the infinite door check taken along line  3 B- 3 B of  FIG. 3A . 
           [0034]      FIG. 4  is a cross-sectional view of a brake assembly for the infinite door check. 
           [0035]      FIG. 5  is a flow chart depicting the operation of the infinite door check. 
           [0036]      FIG. 6  is another flow chart depicting the operation of the infinite door check. 
           [0037]      FIG. 7A  is a graph illustrating brake assembly voltage versus time. 
           [0038]      FIG. 7B  is a graph illustrating brake assembly holding torque versus time according to the voltage-time relationship shown in  FIG. 7A . 
       
    
    
       [0039]    The embodiments, examples and alternatives of the preceding paragraphs, the claims, or the following description and drawings, including any of their various aspects or respective individual features, may be taken independently or in any combination. Features described in connection with one embodiment are applicable to all embodiments, unless such features are incompatible. 
       DETAILED DESCRIPTION 
       [0040]    A conventional automotive vehicle  10  (only a portion shown) typically includes multiple doors  12  (one shown) used for egress and ingress to the vehicle passenger compartment and/or cargo area. In the example, the door  12  is a passenger door. The door  12  is pivotally mounted by hinges  15  (one shown) to a door pillar  14 , such as an A-pillar or B-pillar, about which the door is movable between opened and closed positions. The door  12  has a cavity  16  that typically includes an impact intrusion beam, window regulator, and other devices. A door check module  18  is arranged within the cavity  16 , although the door check module  18  can instead be arranged in the door pillar  14 , if desired. Mounting the door check module  18  near the hinges  15  minimizes the impact on door inertia. 
         [0041]    The door check module  18  is part of a door system  20  ( FIG. 2 ) that holds the door  12  in an open position without the discrete detents typically found in conventional door checks. Instead the system  20  is capable of holding the door in an infinite number of open positions. Moreover, the system  20  can provide a consistent feel during release of the door regardless of vehicle attitude and be used to actively stop the door when an obstacle is detected in the swing path of the door using an obstacle detection sensor. 
         [0042]    Referring to  FIG. 1B , the door check module  18  is connected to the door pillar  14  by a linkage assembly  21 . The linkage assembly  21  transmits the opening and closing forces to the door check module  18  and also stops and holds or only holds the door  12  open when desired. 
         [0043]    Referring to  FIG. 2 , the system  20  includes a controller  22 , or electronic control unit (ECU), that receives inputs from various components as well as sends command signals to the door check module  18  to selectively hold the door  12  open. A direct current (DC) power supply  24  is connected to the controller  22 , which selectively provides electrical power to the door check module  18  in the form of commands. A latch  26 , which is carried by the door  12  ( FIG. 1A ), is selectively coupled and decoupled to a striker  28  mounted to the door pillar  14 . The latch  26  may be a power pull-in latch in communication with the controller  22 , but a conventional mechanical latch may also be used. In one embodiment, the latch  26  includes a sensor that can communicate its open or closed state to the controller  22 . 
         [0044]    A vehicle attitude sensor  29  is in communication with the controller  22  and is used to detect the attitude of the vehicle, which is useful in controlling the motion of the door  12  when released by the door check module  18 . 
         [0045]    In one example, an obstruction sensor  32 , such as an ultrasonic sensor, is in communication with the controller  22  and is used to generate a stop command if an obstruction is detected while the passenger is opening the door. The obstruction sensor  32  is mounted on the outer sheet metal of the door  12 , for example. It should be understood that other sensors, such as optical sensors, can also be used and that other sensor locations, such as in the vehicle's door mirror base, can also be used to sense an obstruction. 
         [0046]    Referring to  FIGS. 2 and 3B , the door check module  18  includes a housing  33 , which may be provided by one or more discrete structures secured to one another. A brake assembly  38  is grounded to the door  12  via the housing  33  and is selectively connected to a shaft member  39 . One suitable brake assembly is available from Sinfonia NC, Model No. ERS-260L/FMF. This brake assembly  38  provides a relatively small amount of holding torque, for example, 8 Nm. 
         [0047]    A gearbox  36  is used to multiply the holding torque provided by the brake assembly  38 . In the example one gearbox is used, although more gearboxes may be used. The gearbox  36  is arranged within the housing  33  and is coupled to the brake assembly  38  by the shaft member  39 . In one example, the gearbox  36  is a spur gear set providing a 6.25:1 reduction. Of course, it should be understood that other gear configurations and gear reductions may be provided. The total holding torque provided by the door check module  18  in the example embodiment is 50 Nm. Any torque applied to the brake assembly  38  above this threshold holding torque will cause the brake to slip, permitting the shaft member  39  to rotate. 
         [0048]    The brake assembly  38  has a normally closed position in which the shaft member  39  is grounded to the housing  33  and prevented from rotating. The brake assembly  38  also includes an opened position corresponding to one of a door closing mode and a door opening mode. In the open position, the brake assembly  38  permits the shaft member  39  to rotate freely. Otherwise, the brake assembly  38  holds or “checks” the door  12  in its current position. 
         [0049]    A position sensor  40 , which is in communication with the controller  22 , monitors the rotation of a component of the door check module  18 , for example, the shaft member  39 . In one example, the position sensor  40  is an integrated Hall effect sensor that detects the rotation of the shaft member  39 . 
         [0050]    Referring to  FIG. 3A , an output shaft  41  of the gearbox  36  is coupled to the linkage assembly  21 . A lever  42  is mounted to the output shaft  41  at one end and to a strap  44  at the other end. The strap  44  is pinned to a bracket  46  fastened to the door pillar  14 . The linkage assembly  21  is designed to provide a holding torque of approximately the same as the desired door holding moment. 
         [0051]    One example brake assembly  38  is shown in more detail in  FIG. 4 . The shaft member  39  is carried by a bearing  50  mounted to the housing  33 . One end  52  communicates with the position sensor  40 , and the other end  54  is connected to the gearbox  36 . A drive ring  56  is secured to the end  54  and supports a permanent magnet  58 . A spring  60 , which may be a leaf spring in one example, is arranged between the drive ring  56  and permanent magnet  58  to bias the permanent magnet  58  away from the housing  33 . A magnetic field generated by the permanent magnet  58  pulls the drive ring  56  with a much greater force than the spring  60  toward the housing  33 . Friction material  62  is supported by the housing  33  and engages the permanent magnet  58  in the normally closed position to provide the torque at which the permanent magnet  58  will slip with respect to the housing  33 , again, about 8 Nm. 
         [0052]    A magnetic flux circuit, or coil  64 , is arranged within the housing  33  and communicates with the controller  22  via wires  66 . When energized with a defined polarity current, the coil  64  creates a counteracting magnetic flux to the permanent magnet  58  that is sufficient to overcome the magnetic field of the permanent magnet  58 , thus allowing the spring  60  to move the permanent magnet  58  out of engagement with the friction material  62  to the position shown in  FIG. 4 . In this opened position, the shaft member  39  is permitted to rotate freely relative to the housing  33 . The brake assembly components can be reconfigured in a manner different than described above and still provide desired selective brake hold torque. 
         [0053]    The magnetic flux circuit, or coil  64  can also be powered in reverse polarity to add to the magnetic flux of the permanent magnet  58 . This is advantageous when a stop command is generated by the controller  22  due to the detection of an obstruction. It has been shown that the addition coil generated magnetic flux increase the maximum holding torque by ˜50%, for example. Therefore, the brake arresting torque increases to 12 Nm in such an example, which in turn provides a maximum arresting torque of 75 Nm. 
         [0054]    One example operating mode  70  is shown in  FIG. 5 . With the brake assembly  38  in the normally closed position, a holding torque is generated to maintain the door  12  in its current position. In the absence of slippage in the brake assembly  38 , the door velocity is detected as zero via the position sensor  40 . 
         [0055]    The door  12  is pushed or pulled further open or closed by the user, which causes the linkage assembly  21  to rotate the output shaft  41  and back-drive the gearbox  36  and shaft member  39 . When enough torque has been applied to slip the brake torque of the normally closed brake assembly  38  (in the example, 50 Nm), the shaft member  39  will rotate. An angular movement of the shaft member  39  is thus detected by the position sensor  40 , which is indicative of rotation of the output shaft  41 . 
         [0056]    A detected threshold angular movement, for example, 2°, provides an input that is interpreted as a desired door motion command by the controller  22 . Of course, other angular thresholds can be used, if desired. The position sensor  40  is used to detect the angular position of the door  12  as well as door velocity, which may be useful in controlling the brake assembly  38  based upon vehicle attitude. 
         [0057]    Thus, in response to the input from the position sensor  40 , the controller  22  will command the brake assembly  38  to release the shaft member  39 , which will then rotate freely relative to the housing  33 , permitting the door  12  to move. Once the shaft member  39  angular movement and/or velocity has been detected by the position sensor  40  to be about 0 (indicative of arrested door motion), the coil  64  is de-energized to reengage the brake assembly  38  and hold the door  12  in its current position. 
         [0058]    Door motion is arrested at the fully open and fully closed positions. Additionally, the user can physically hold the door  12  in a desired position, preventing further movement of the door  12 , which will be detected by the position sensor  40 . The controller  22  then de-energizes the brake assembly  38 , which will hold the door  12  where the user stopped the door  12 , providing an “infinite” door check. That is, the door  12  can be held by the door check module  18  in any position rather than only in discrete detent positions. This feature is particular useful in tight parking situations where a door cannot be fully opened. The door can then be positioned in close proximity to an obstacle adjacent to the door and held by the user, at which point the brake assembly  38  will hold the door position, thus providing a maximum opening for the user to enter and exit the vehicle. 
         [0059]    In a further example operating mode  80  is shown in  FIG. 6 . whereby a stop command is generated by the controller  22  due to an obstacle signal from obstacle sensor  32 . This stop command includes a reverse polarity current to the break that increase the break holding torque to 12 Nm, which in turn results in a door arresting torque of 75 Nm by multiplication of the gearbox  36 . The arresting torque ensures a rapid arresting of the door to prevent contact with the obstacle. When the door velocity is detected as zero via the position sensor  40  the reverse polarity current is dropped and the holding torque of the door check module  18  reverts to 50 Nm. The holding torque decay of the brake assembly  38  can be adjusted with pulse-width modulation of the coil  64 . For example the nominal break holding torque can be reduced to 6.4 Nm by applying approximately 4 V to the coil through pulse width modulation and thus provide a door check hold torque of approximately 40 Nm on level ground. In a further example, the vehicle attitude is detected with the attitude sensor  29  to vary the holding torque provided by the brake assembly  38  to provide a consistent holding torque regardless of vehicle incline or decline, which creates predictable door motion for the user. For example, a greater holding torque would be applied by the brake assembly  38  when the vehicle is on an incline than when the vehicle is on level ground. 
         [0060]    In a second example it may be desirable to “soft” release the brake assembly  38  to prevent an abrupt door movement that may cause an undesirable door feel for the customer. For example, 50 Nm of holding torque may produce a force in the linkage assembly  21  at the door pillar  14  of 700-900 N, which is capable of producing an audible sheet metal popping sound due to the sudden release of the stored hold moment energy. To address this potential undesired scenario, a soft release function is used, as shown in  FIG. 7A , to ramp the pulse-width modulation signal from the controller  22  over, for example, 0.2 seconds, to full strength. As a result, the electrical counter field to the permanent magnetic field is slowly increased, thus reducing the brake hold torque from full strength to released, as shown in  FIG. 7B , over the 0.2 seconds, which provides a “soft” release of the brake action. In the example, a gradual, linear increase in voltage provides a smooth, non-linear decay of holding torque. However, it should be understood that other voltage-torque-time relationships may be provided electrically and/or mechanically to provide a desired door feel. 
         [0061]    It should also be understood that although a particular component arrangement is disclosed in the illustrated embodiment, other arrangements will benefit herefrom. Although particular step sequences are shown, described, and claimed, it should be understood that steps may be performed in any order, separated or combined unless otherwise indicated and will still benefit from the present invention. 
         [0062]    Although the different examples have specific components shown in the illustrations, embodiments of this invention are not limited to those particular combinations. It is possible to use some of the components or features from one of the examples in combination with features or components from another one of the examples. 
         [0063]    Although an example embodiment has been disclosed, a worker of ordinary skill in this art would recognize that certain modifications would come within the scope of the claims. For that reason, the following claims should be studied to determine their true scope and content.