Patent Publication Number: US-2010117438-A1

Title: Seatbelt device

Description:
BACKGROUND 
     The present application relates to a seatbelt device for holding an occupant such as a driver to a seat in an automobile, for example, a seatbelt controller for controlling retracting of the seatbelt, a seatbelt control method, and a program. 
     In vehicles such as an automobile, a seatbelt device constituted by a seatbelt or the like for holding an occupant such as a driver to a seat, for example, is equipped in general. As such seatbelt devices, those provided with a seatbelt retractor, for example, are known (see e.g., Japanese Unexamined Patent Application Publication No. 2005-231594, incorporated by reference herein). The seatbelt retractor is constituted by, for example, an electric motor for retracting a seatbelt, a seatbelt controller for controlling the motor, and a return spring for urging a belt retracting shaft (torsion bar) coupled to a rotating shaft of the motor in a retracting direction through a clutch or the like. 
     However, depending on driving start timing of the motor, a noise might occur in the clutch or the like, which still leaves room for improvement. 
     SUMMARY 
     One disclosed embodiment relates to a seatbelt device comprising a seatbelt, a spool for retracting the seatbelt, and a motor for rotating and driving the spool. The seatbelt device further includes urging means for urging the seat belt in a retracting direction, first retracting means for starting retracting of the seatbelt by the urging means, and second retracting means for starting the retracting of the seatbelt by the motor. The second retracting means starts the retracting of the seatbelt if, after the retracting of the seatbelt by the first retracting means is started, a retracting speed thereof is at a predetermined value or less and the retracting of the seatbelt has not been stopped. 
     Another embodiment relates to a seatbelt controller for controlling a device including a seatbelt, a spool for retracting the seatbelt, a motor for rotating and driving the spool, and urging means for urging the seatbelt in a retracting direction. The urging means comprises first retracting means for starting retracting of the seatbelt by the urging means, and second retracting means for starting the retracting of the seatbelt by the motor. The second retracting means starts the retracting of the seatbelt if, after the retracting of the seatbelt by the first retracting means is started, a retracting speed thereof is at a predetermined value or less and the retracting of the seatbelt has not been stopped. 
     Yet another embodiment relates to a seatbelt control method for controlling a device including a seatbelt, a spool for retracting the seatbelt, a motor for rotating and driving the spool, and urging means for urging the seatbelt in a retracting direction. The method comprises a first step for starting retracting of the seatbelt by the urging means; and a second step for starting the retracting of the seatbelt by the motor, provided that after the retracting of the seatbelt by the first step is started, a retracting speed thereof is at a predetermined value or less and the retracting of the seatbelt has not been stopped. 
     Still another embodiment relates to a program for controlling a device including a seatbelt, a spool for retracting the seatbelt, a motor for rotating and driving the spool, and urging means for urging the seatbelt in a retracting direction. The program has a computer execute a first step for starting retracting of the seatbelt by the urging means; and a second step for starting the retracting of the seatbelt by the motor, provided that after the retracting of the seatbelt by the first step is started, a retracting speed thereof is at a predetermined value or less and the retracting of the seatbelt has not been stopped. 
     It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only, and are not restrictive of the invention as claimed. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       These and other features, aspects, and advantages of the present invention will become apparent from the following description, appended claims, and the accompanying exemplary embodiments shown in the drawings, which are briefly described below. 
         FIG. 1  is a block diagram illustrating a configuration example and a connection state thereof of a seatbelt retractor according to an exemplary embodiment. 
         FIG. 2  is a perspective view illustrating a configuration of a motor retractor. 
         FIG. 3  is a perspective view illustrating a configuration of a seatbelt device. 
         FIG. 4  is a flowchart illustrating contents of belt retracting control. 
         FIG. 5  is a graph illustrating an operation example of the seatbelt device. 
         FIG. 6  is a flowchart illustrating contents of belt retracting control according to another exemplary embodiment. 
         FIG. 7  is a graph illustrating an operation example of a seatbelt device. 
     
    
    
     DETAILED DESCRIPTION 
     The disclosed embodiments were made in view of the above circumstances and has an object to provide a seatbelt device which can suppress a noise when a belt is retracted, a seatbelt controller, and a seatbelt control method. 
     According to an exemplary embodiment, a seatbelt device includes a seatbelt, a spool for retracting the seatbelt, and a motor for rotating and driving the spool. The seatbelt device further includes urging means for urging the seat belt in a retracting direction, first retracting means for starting retracting of the seatbelt by the urging means, and second retracting means for starting the retracting of the seatbelt by the motor. The second retracting means starts the retracting of the seatbelt if, after the retracting of the seatbelt by the first retracting means is started, a retracting speed thereof is at a predetermined value or less and the retracting of the seatbelt has not been stopped. 
     In the seatbelt device, it may be so configured that the second retracting means starts retracting of the seatbelt by the motor, provided that a retracted amount of the seatbelt is a predetermined value or more in addition to the condition. 
     According to another exemplary embodiment, a seatbelt controller controls a device including a seatbelt, a spool for retracting the seatbelt, a motor for rotating and driving the spool, and urging means for urging the seatbelt in a retracting direction. The urging means comprises first retracting means for starting retracting of the seatbelt by the urging means, and second retracting means for starting the retracting of the seatbelt by the motor. The second retracting means starts the retracting of the seatbelt if, after the retracting of the seatbelt by the first retracting means is started, a retracting speed thereof is at a predetermined value or less and the retracting of the seatbelt has not been stopped. 
     According to an exemplary embodiment, a seatbelt control method for controls a device including a seatbelt, a spool for retracting the seatbelt, a motor for rotating and driving the spool, and urging means for urging the seatbelt in a retracting direction. The method comprises a first step for starting retracting of the seatbelt by the urging means; and a second step for starting the retracting of the seatbelt by the motor, provided that after the retracting of the seatbelt by the first step is started, a retracting speed thereof is at a predetermined value or less and the retracting of the seatbelt has not been stopped. 
     According to an exemplary embodiment, a program controls a device including a seatbelt, a spool for retracting the seatbelt, a motor for rotating and driving the spool, and urging means for urging the seatbelt in a retracting direction. The program has a computer execute a first step for starting retracting of the seatbelt by the urging means; and a second step for starting the retracting of the seatbelt by the motor, provided that after the retracting of the seatbelt by the first step is started, a retracting speed thereof is at a predetermined value or less and the retracting of the seatbelt has not been stopped. 
     According to the present invention, a seatbelt controller, a seatbelt control method, and a program for a seatbelt device are provided that are configured to suppress a noise when a belt is retracted. 
     An embodiment of a seatbelt device, a seatbelt controller, a seatbelt control method, and a program according to the present invention will be described below referring to the attached drawings. 
     According to one embodiment, a seatbelt control apparatus is installed in an ECU (Electronic Control Unit)  11  of a motor vehicle as shown in  FIG. 1 . The ECU  11  controls a motor  121  of a motor retractor  12 . The ECU  11  and the motor retractor  12  are provided in a seatbelt retractor  10  for automatically retracting a seatbelt. As shown in  FIG. 1 , the ECU  11  has a CPU (Central Processing Unit)  111 , a motor driver  112 , a current sensor  113 , and a data storage section  114 . Although not illustrated, the ECU  11  also includes ROM (Read Only Memory) and RAM (Random Access Memory) and the like. 
     The CPU  111  controls at least a portion of the operation of the seatbelt. Various types of sensors such as a seatbelt fastening sensor  22  (to be detailed later) and the like are connected to the CPU  111  (e.g., via a cord, wire, cable, etc.). To perform vehicle control, the CPU  111  executes a control program stored in the ROM or the like while causing, for example, the RAM to temporarily store various types of data. At this time, sensor information is used, if needed. 
     The data storage section  114  includes a writable memory such as an EEPROM (Electrically Erasable PROM) or a flash memory. The data storage section  114  (e.g., data storage portion) includes a parameter, a table, a flag, and the like for use in control stored or updated in advance or during control. 
     The motor driver  112  is electrically connected to the CPU  111  and a power supply  21 . The motor driver  112  drives the motor  121  in accordance with a control signal from the CPU  111 . The power supply  21  (e.g., an in-vehicle battery) supplies a power supply voltage to the motor driver  112 . The current sensor  113  is disposed between, for example, the motor driver  112  and the motor  121 . The current sensor  113  detects the value of a current flowing through the motor  121  and outputs the detected value to the CPU  111 . 
     As shown in, for example,  FIG. 2 , the motor retractor  12  controlled by the ECU  11  includes the motor  121 , a frame  122 , a spool  123 , a return spring  124  (urging means), and a power transmission mechanism  125 . The frame  122  is a substantially U-shaped framework of the motor retractor  12 . The frame  122  supports various components such as the ECU  111  and the motor  121 , that are secured to the frame  122  in the form as shown in  FIG. 2 . 
     The motor  121  is an electric motor with a rotating shaft coupled to the spool  123 . The motor  121  is rotatable in both forward and backward directions. The motor  121  rotatably drives the spool  123 . 
     The spool  123  retracts a belt  31 . The spool  123  is rotatably fixed to the frame  122 . The lock mechanism portion  123  is coupled to the spool  123 . A spool sensor  23  is supported by the frame  122  proximate to the outer periphery of the spool  123 . The spool sensor  23  is configured to detect a rotating direction and a rotation speed of the spool  123 . According to one exemplary embodiment, the spool sensor  23  includes two lead switches. The spool sensor  23  generates a pulse as it detects a magnetic field from a magnet rotated in conjunction with the rotation of the spool  123 . A spool counter, such as the CPU  111 , counts the pulses to detect the rotation speed of the spool  123 . The two lead switches are arranged while being displaced in the rotating direction so that the pulse widths are overlapped and the phases are different. As a result, the CPU  111  can detect the rotating direction of the spool  123  on the basis of which of the lead switches generates the pulse first. 
     A lock mechanism  123   a  is connected to the spool  123 . The lock mechanism  123   a  has a torsion bar (not illustrated). A lock gear and a cam are coupled to one end of the torsion bar while the spool  123  is coupled to the other end of the torsion bar. The cam is coupled to the spool  123  directly or through reduction gears. An ELR (emergency locking retractor) switch  123   b  is provided proximate to the outer periphery of the cam such that it is in contact with the circumferential surface of the cam. The ELR switch  123   b  switches an inner contact (to the on or off position) in conjunction with the rotational position (projections of the cam) of the cam. The ELR switch  123   b  is positioned such that it is tripped by the cam connected to the spool  123  when the belt  31  is retracted an amount exceeding a predetermined level or value. The ELR switch  123   b  is used to lock rotational operation of the torsion bar in the event of, for example, an emergency. Also, the ELR switch  123   b  can detect the retracted amount of the belt  31 . 
     The power transmission mechanism  125  includes a return spring  124 , a predetermined number of gears, and, for example, a clutch mechanism consisting of a one-way clutch that engages in the retraction direction of the belt  31 . The power transmission mechanism  125  transmits power generated by the motor  121  to the torsion bar and the spool  123  through a clutch or the like. The power transmission mechanism  125  is secured to, for example, the frame  122 . The return spring  124  is directly connected to the spool  123 . The motor  121  is coupled with the spool  123  via the clutch mechanism of the power transmission mechanism  125 . 
     The motor retractor  12  can take up the belt  31  with the spool  123  through the rotation of the torsion bar. The return spring  124  is connected to the end of the torsion bar opposite the lock gears. According to an exemplary embodiment, the return spring  124  is a flat spiral spring. The return spring  124  is incorporated in the power transmission mechanism  125 . The return spring  124  biases the spool  123  in the retraction direction of the belt  31 . If the motor  121  is not activated and no withdrawing force is applied to the belt  31 , the urging force of the return spring  124  acts on the belt  31 , causing the belt  31  to be retracted. The return spring  124  is loosened or relaxed when the motor  121  rotates in the retraction direction of the belt  31 . Greater retracted amount of the belt  31  results in weaker retracting force of the return spring  124 . The retracting force is configured such that it does not give an occupant a feeling of tightness. In contrast, retracting force of the motor  121  is set greater than that of the return spring  124 . 
     A seatbelt retractor  10  ( FIG. 2 ) as described above is used in, for example, a seatbelt apparatus  30  as shown in  FIG. 3 . The seatbelt apparatus  30  includes the seatbelt retractor  10 , a belt  30  (e.g., seatbelt, webbing, etc.), a belt anchor  32 , a guide anchor  33 , a tongue plate  34 , and a buckle  35  (belt fastening and releasing means). The seatbelt retractor  10  is installed in, for example, a vehicle seat  100  (driver&#39;s seat, a passenger seat, a rear seat, and the like). The seatbelt retractor  10  is secured to, for example, the inside of the side of a vehicle body. 
     The belt  31  restrains an occupant in a seat. The belt  31  extends between the seatbelt retractor  10  and the belt anchor  32 . The belt anchor  32  secures one end of the belt  31  to the passenger compartment of a vehicle, such as to the floor of the vehicle body or the seat. The belt  31  is folded back the belt  31  in the vicinity of the shoulder of an occupant by the guide anchor  33 . The guide anchor  33 , through which the belt  31  is inserted, is secured to the side of a vehicle. 
     The belt  31  is fastened down to restrain the occupant with the tongue plate  34  and the buckle  35 . The tongue plate  34  is slidably supported on the belt  31  that is folded back at the guide anchor  33 . The buckle  35  has an insertion opening (slot)  35   a  formed in the vicinity of the waist of an occupant. When the tongue plate  34  is inserted into the insertion opening  35   a , the tongue plate  34  is releasably engaged with the buckle  35 . 
     The seatbelt fastening sensor  22  ( FIG. 1 ) is provided in the buckle  35  for detecting that the tongue plate  34  is engaged. While the tongue plate  34  is engaged with the buckle  35 , a signal detected by the seatbelt fastening sensor  22  is outputted to the seatbelt retractor  10  (specifically the CPU  111  as shown in  FIG. 1 ) through a cord. For this reason, the ECU  111  can detect that the belt  31  is fastened or released (whether the buckle  35  is released or not) according to the presence of the signal from the seatbelt fastening sensor  22 . 
     The seatbelt retractor  10  repeatedly executes a series of processing steps (belt retracting control) shown in  FIG. 4 , for example. According to an exemplary embodiment, the processing steps are executed by the CPU  111  reading a predetermined program from the ROM in the ECU  11 . 
     In a first Step S 11  of the exemplary processing shown in  FIG. 4 , the CPU  111  senses a signal from the seatbelt wearing sensor  22 , for example, to determine if the buckle  35  has been released. If the buckle  35  has been released, processing Step S 12  is executed. Then, at Step S 12 , the return spring  124  begins to retract (e.g., take-up) the belt  31 . In the following step S 13 , the CPU  111  detects a retracting speed  51  (corresponding to a rotation speed of the spool  123 ) on the basis of the signal from the spool sensor  23 . 
     Subsequently, at Step S 14 , the CPU  111  reads a predetermined retracting speed S 0  stored in the data storage portion  114 . The retracting speed S 0  is set at a retracting speed at which no noise is generated at the clutch of the power transmission mechanism portion  125 . The retracting speed S 0  may determined, for example, by experiments and the like. In Step S 14 , the CPU  111  compares the retracting speed S 1  to the predetermined retracting speed S 0 . The CPU  111  repeats the processing at Steps S 13  and S 14  until the retracting speed S 1  falls to the retracting speed S 0  or lower. More specifically, it is set so that a period when the retracting speed of the belt  31  caused by the return spring  124  is larger than the rotation speed of the motor  121  (e.g., the period when the noise can easily occur) lasts for a short time at the beginning of motor driving. 
     Once the retracting speed S 1  falls to the retracting speed S 0  or less, the CPU  111  determines if the retracting operation has not been stopped (e.g., the retracting speed S 1  is not “0”) at the subsequent Step S 15 . If it is determined that the retracting operation has been stopped at Step S 15 , the CPU  111  finishes the processing in  FIG. 4 . In this case, even if the retracting operation has been stopped since the belt  31  is caught by a human body or the like during the retracting, it is considered that the belt  31  is not completely stored. If it is determined that the belt  31  is not completely stored, the CPU  111  executes predetermined failsafe processing such as lighting of an alarm lamp or retracting processing with a low output by the motor  121 . 
     If it is determined at Step S 15  that the retracting operation of the belt  31  has not been stopped, the retracting processing of the belt  31  by the motor  121  is started by the CPU  111  at the subsequent Step S 16 . Specifically, the CPU  111  reads a control parameter according to a situation at that time from a table stored in the data storage portion  114 . Then, the CPU  111  generates a PWM (Pulse Width Modulation) signal of a predetermined duty ratio according to the control parameter. Subsequently, the CPU  111  outputs the PWM signal and a control signal directing a rotation direction of the motor  121  to the motor driver  112 , respectively. Then, the motor driver  112  having received the signal generates a driving voltage by adjusting the supply voltage by the PWM signal. The motor driver  112  applies the driving voltage to the motor  121 . As a result, the motor  121  is rotated at a speed on the basis of the duty ratio of the driving voltage, and the belt  31  is retracted by the spool  123 . The retraction processing in  FIG. 4  is finished when the belt  31  has been completely stored and processing at Step S 16  is finished. 
     Referring now to  FIG. 5 , when the buckle  35  is released by the user at timing t 1 , by means of the processing in  FIG. 4 , the belt  31  is retracted by the return spring  124  as indicated by a line L 11 . If the retracting speed (retracting speed S 1 ) has fallen to a predetermined level (retracting speed S 0 ) or less and the retracting has not been stopped yet, the motor  121  is driven at timing t 2  to retract of the belt  31 , as indicated by a line L 12 . 
     It may be so configured that the CPU  111  performs reading of the control parameters when an ignition key of a vehicle is turned on, for example, and stores them in a register of the RAM or the like. 
     As described above, the seatbelt retractor  10  does not drive the motor  121  while the retracting speed of the belt  31  by the return spring  124  is still relatively fast and a noise might occur if the motor  121  is to be driven. The driving of the motor  121  is started after the retracting speed of the belt  31  by the return spring  124  has become sufficiently slow. Therefore, according to the seatbelt retractor  10 , the noise during the belt retracting can be suppressed. 
     A seatbelt apparatus, a seatbelt control apparatus, a seatbelt control method, and a program according to another exemplary embodiment will be described below. The apparatus configuration of this embodiment is similar to the embodiment described above, and, therefore, repeated descriptions of the same sections are omitted for the sake of simplicity. 
     According to an exemplary embodiment, the seatbelt retractor  10  repeatedly performs a series of processing steps (belt retraction control) in  FIG. 6 , in place of the processing in  FIG. 4 , at predetermined time intervals according to, for example, a program. In the processing steps in  FIG. 6 , the CPU  111  performs the processing steps in steps S 21  through S 24  which are the same as those in steps S 11  through S 14  shown in  FIG. 4 . 
     Subsequently, at Step S 25 , the CPU  111  uses the ELR switch  123   b  to determine if a retracted amount M 1  of the belt  31  meets or exceeds a predetermined value M 0 . Specifically, the ELR switch  123   b  is arranged so that it is switched by a cam coupled to the spool  123  when the retracted amount M 1  reaches the predetermined value M 0  or more. Thus, at a position where the ELR switch  123   b  is switched, the retracted amount M 1  becomes the predetermined value M 0 . Therefore, the CPU  111  determines that the retracted amount M 1  becomes the predetermined value M 0  or more when the ELR switch  123   b  is switched after the buckle  35  is released, for example. The retracting speed S 0  and the predetermined value M 0  are set at a retracting speed and a retracted amount in advance (e.g., by experiments and the like) such that the retracting force of the return spring  124  becomes sufficiently weak to a degree that a noise will not occur in the clutch of the power transmission mechanism portion  125  or the like. Because both the retracting speed and the retracted amount are considered, it can be detected with higher accuracy that the retracting force of the return spring  124  has weakened or not to such a degree that a noise will not occur. 
     Step S 25  continues until the retracted amount M 1  of the belt  31  meets or exceeds the predetermined value M 0 . The CPU  111  then executes processing at Steps S 26  and S 27 , which is the processing similar to Steps S 15  and S 16 . That is, similarly to Step S 15 , the CPU  111  determines at Step S 26  if the retracting operation has not been stopped yet. If it is determined at Step S 26  that the retracting operation of the belt  31  has not been stopped yet, the CPU  111  starts retracting processing of the belt  31  by the motor  121  at the subsequent Step S 27  similarly to Step S 16 . This retracting processing is finished when the processing at Step S 27  is finished and when the belt  31  is completely stored, for example. 
     If the buckle  35  is released by the user at the timing t 1  in  FIG. 7 , for example, the retracting of the belt  31  by the return spring  124  as indicated by the line L 11  in  FIG. 7  is started. Then, at timing t 2 , the retracting speed (retracting speed S 1 ) falls to the predetermined level (retracting speed S 0 ) or less. After that, at timing t 3 , if the retracted amount M 1  of the belt  31  becomes the predetermined value M 0  or more and the retracting has not been stopped yet, the motor  121  is driven, and by means of the motor  121 , the retracting of the belt  31  as indicated by a line L 12  in  FIG. 7  is performed. 
     As described above, the seatbelt retractor  10  can detect with higher accuracy whether or not the retracting force of the return spring  124  has weakened by taking into account of not only the retracting speed but also the retracted amount. Therefore, according to the seatbelt retractor  10 , the noise during the belt retracting can be suppressed more reliably. 
     The processing according to the program in each of the above embodiments is not limited to the order shown in each flowchart but its order can be changed arbitrarily within a range not departing from the gist of the present invention. The device configuration shown in  FIGS. 1 to 3  can be changed as appropriate according to an application or the like. 
     For example, a method for detecting the retracted amount is arbitrary. In addition to the ELR switch  123   b , another switch may be provided in the vicinity of the outer periphery of the cam so as to calculate more precisely whether or not the retracted amount of the belt  31  is at the predetermined value or more or not. Also, the CPU  111  may acquire the amount by calculation from a driven amount of the motor  121 , a rotated amount of the spool  123  and the like. 
     The above embodiments show examples in which the seatbelt device  30  is provided at the seat of a vehicle, but not limited to the vehicle, the present invention may be applied to a seat of an aircraft or the like. 
     The program in each of the above embodiments may be those that can be stored in a computer-readable recording medium such as flexible disk, CD-ROM (Compact Disk Read-Only Memory), DVD (Digital Versatile Disk), MO (Magneto-Optical Disk) and the like for distribution. In this case, by installing the program in a predetermined computer, the above-mentioned processing can be executed. Also, the program in each of the above embodiments may be those that can be stored in a storage device (hard disk or the like) in a server provided on a communication network (the Internet, intranet and the like, for example), superimposed on a carrier wave, for example, and downloaded to a local computer or read out of the server any time and started and executed at the local computer. If a part of the function is handled by an OS (Operating System), only the portion other than the function handled by the OS may be distributed or transferred. 
     Means for realizing the function of the ECU  11  is not limited to software but a part of or the whole of it may be realized by dedicated hardware. 
     The priority application, Japanese Patent Application N. 2008-287209, filed Nov. 7, 2008 including the specification, drawings, claims and abstract, is incorporated herein by reference in its entirety. 
     The construction and arrangements of the seatbelt apparatus, as shown in the various exemplary embodiments, are illustrative only. Although only a few embodiments have been described in detail in this disclosure, many modifications are possible (e.g., variations in sizes, dimensions, structures, shapes and proportions of the various elements, values of parameters, mounting arrangements, use of materials, colors, orientations, etc.) without materially departing from the novel teachings and advantages of the subject matter described herein. Some elements shown as integrally formed may be constructed of multiple parts or elements, the position of elements may be reversed or otherwise varied, and the nature or number of discrete elements or positions may be altered or varied. The order or sequence of any process, logical algorithm, or method steps may be varied or re-sequenced according to alternative embodiments. Other substitutions, modifications, changes and omissions may also be made in the design, operating conditions and arrangement of the various exemplary embodiments without departing from the scope of the present disclosure.