Patent Publication Number: US-2010121533-A1

Title: Seatbelt control apparatus

Description:
BACKGROUND 
     The present application relates to a seatbelt apparatus for restraining an occupant of a vehicle, a seatbelt control apparatus for controlling the retraction of a seatbelt, a seatbelt control method. 
     A vehicle such as a motor vehicle is generally provided with a seatbelt apparatus consisting of a seatbelt and the like for restraining an occupant such as a driver. As such a seatbelt apparatus, a seatbelt apparatus having, for example, a seatbelt retractor is known (see e.g., Japanese Unexamined Patent Application Publication No. 2005-231594, incorporated by reference herein). Such a seatbelt retractor consists of, for example, an electric motor for retracting a seatbelt, a seatbelt control apparatus for controlling the motor, and a return spring for urging a belt retraction shaft (a torsion bar) connected to the rotating shaft of the motor via a clutch or the like toward the retraction direction. However, such a seatbelt apparatus may experience abnormal noise emission from the clutch, depending on the timing on when the motor starts to drive. 
     SUMMARY 
     One disclosed embodiment relates to a seatbelt apparatus including a seatbelt, a spool for retracting the seatbelt, a motor for rotatably driving the spool, and urging mechanism for urging the seatbelt toward a retracting direction. The seat belt apparatus further includes belt attaching/detaching mechanism, a belt releasing detecting mechanism and, a motor control mechanism or motor controller. The belt attaching/detaching mechanism fastens or releases the seatbelt. The belt releasing detecting mechanism detects that the seatbelt is released from the belt attaching/detaching mechanism. The motor controller causes the motor to start to take up the seatbelt on the condition that a predetermined amount of time passes since the belt releasing detecting mechanism detects that the seatbelt is released. 
     Another disclosed embodiment relates to a seatbelt control apparatus that controls an apparatus including a seatbelt, a spool for retracting the seatbelt, a motor for rotatably driving the spool, urging mechanism for urging the seatbelt toward a retracting direction; and belt attaching/detaching mechanism adapted to attach/detach the seatbelt for fastening or releasing the seatbelt. The seatbelt control apparatus comprises belt releasing detecting mechanism, and motor control mechanism or motor controller. The belt releasing detecting mechanism detects that the seatbelt is released from the belt attaching/detaching mechanism. The motor control mechanism or motor controller causes the motor to start to take up the seatbelt on the condition that a predetermined amount of time passes since the belt releasing detecting mechanism detects that the seatbelt is released. 
     Still another disclosed embodiment relates to a seatbelt control method for controlling an apparatus which includes a seatbelt, a spool for retracting the seatbelt, a motor for rotatably driving the spool, urging mechanism for urging the seatbelt toward a retracting direction, and belt attaching/detaching mechanism adapted to attach/detach the seatbelt for fastening or releasing the seatbelt. The seatbelt control method comprises a first step, a second step, and a third step. The first step involves determining an amount of time during which an urging force of the urging mechanism becomes weaker than a predetermined level. The second step involves detecting that the seatbelt is released from the belt attaching/detaching mechanism. The third step involves causing the motor to start to take up the seatbelt on the condition that the amount of time determined in the first step passes since the second step detects that the seatbelt is released. 
     Yet another disclosed embodiment relates to a program or method for controlling an apparatus which includes a seatbelt, a spool for retracting the seatbelt, a motor for rotatably driving the spool, urging mechanism for urging the seatbelt toward a retracting direction, and belt attaching/detaching mechanism adapted to attach/detach the seatbelt for fastening or releasing the seatbelt. The method enables a computer to carry out processing comprising a belt releasing detecting step, and a motor control step. The belt releasing detecting step involves detecting that the seatbelt is released from the belt attaching/detaching mechanism. The motor control step involves causing the motor to start to take up the seatbelt on the condition that a predetermined amount of time passes since the belt releasing detecting step detects that the seatbelt is released. 
     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 showing an example of a configuration and connection of a seatbelt retractor with regard to the seatbelt apparatus, the seatbelt control apparatus, and the seatbelt control method according to an embodiment. 
         FIG. 2  is a perspective view showing the configuration of the motor retractor. 
         FIG. 3  is a perspective view showing the configuration of a seatbelt apparatus. 
         FIG. 4  is a flowchart illustrating belt retraction control. 
         FIG. 5  is a graph showing an example of the operation of a seatbelt apparatus. 
         FIG. 6  is a flowchart illustrating belt retraction control with regard to the seatbelt apparatus, the seatbelt control apparatus, and the seatbelt control method according to another exemplary embodiment. 
         FIG. 7  is a graph showing an example of the operation of a seatbelt apparatus. 
     
    
    
     DETAILED DESCRIPTION 
     According to a first aspect, a seatbelt apparatus includes a seatbelt, a spool for retracting the seatbelt, and a motor for rotatably driving the spool. The seat belt apparatus further includes urging mechanism, belt attaching/detaching mechanism, belt releasing detecting mechanism, and motor control mechanism or motor controller. The urging mechanism biases the seatbelt toward a retraction direction. The belt attaching/detaching mechanism fastens or releases the seatbelt. The belt releasing detecting mechanism detects that the seatbelt is released from the belt attaching/detaching mechanism. The motor controller causes the motor to start to take up the seatbelt on the condition that a predetermined amount of time passes since the belt releasing detecting mechanism detects that the seatbelt is released. In the seatbelt apparatus, the motor controller may be configured to cause the motor to start to take up the seatbelt on the condition that the retracted amount of the seatbelt is equal to or greater than a predetermined level, in addition to the condition described above. 
     According to the second aspect, a seatbelt control apparatus controls a seatbelt apparatus including a seatbelt, a spool for retracting the seatbelt, and a motor for rotatably driving the spool. The seat belt apparatus further includes urging mechanism, belt attaching/detaching mechanism, belt releasing detecting mechanism, and motor control mechanism or motor controller. The urging mechanism biases the seatbelt toward a retraction direction. The belt attaching/detaching mechanism fastens or releases the seatbelt. The belt releasing detecting mechanism detects that the seatbelt is released from the belt attaching/detaching mechanism. The motor controller causes the motor to start to take up the seatbelt on the condition that a predetermined amount of time passes since the belt releasing detecting mechanism detects that the seatbelt is released. 
     According to the third aspect, a seatbelt control method controls an apparatus including a seatbelt, a spool for retracting the seatbelt, and a motor for rotatably driving the spool. The seat belt apparatus further includes urging mechanism, belt attaching/detaching mechanism, belt releasing detecting mechanism, and a motor control mechanism or motor controller. The urging mechanism biases the seatbelt toward a retraction direction. The belt attaching/detaching mechanism fastens or releases the seatbelt. The belt releasing detecting mechanism detects that the seatbelt is released from the belt attaching/detaching mechanism. The motor controller causes the motor to start to take up the seatbelt on the condition that a predetermined amount of time passes since the belt releasing detecting mechanism detects that the seatbelt is released. 
     According to the fourth aspect, a method controls an apparatus including a seatbelt, a spool for retracting the seatbelt, and a motor for rotatably driving the spool. The seat belt apparatus further includes urging mechanism, belt attaching/detaching mechanism, belt releasing detecting mechanism, and motor control mechanism or motor controller. The urging mechanism biases the seatbelt toward a retraction direction. The belt attaching/detaching mechanism fastens or releases the seatbelt. The belt releasing detecting mechanism detects that the seatbelt is released from the belt attaching/detaching mechanism. The motor controller causes the motor to start to take up the seatbelt on the condition that a predetermined amount of time passes since the belt releasing detecting mechanism detects that the seatbelt is released. 
     The present application discloses a seatbelt apparatus, a seatbelt control apparatus, and a seatbelt control method which can suppress abnormal noise emitted during the retraction of a belt. Also, the disclosed apparatus and methods can drive a motor more efficiently. 
     According to one embodiment, a seatbelt controller includes 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  includes 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 method 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 , an urging mechanism (e.g., a return spring  124 ), 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  is a component around which a belt  31  is wound. The spool  123  is rotatably secured to the frame  122 . 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 belt fastening and releasing mechanism (e.g., a buckle  35 ). 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 performs, for example, a series of processing steps (belt retraction control) as shown in  FIG. 4 . In these processing steps, the CPU  111  in, for example, the ECU  11  reads out and executes a predetermined method from the ROM. 
     In step S 11  of the processing steps in  FIG. 4 , the CPU  111  detects a signal from the seatbelt fastening sensor  22  to determine if the buckle  35  is released. If the buckle  35  is released, (e.g., released by a user), the CPU  111  determines in step S 11  that the buckle  35  is released. Then, in 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  starts a counter, beginning counting from the reset state (counter=0). The counter may be mechanical or may be formed in a method. 
     In the following step S 14 , the CPU  111  checks a predetermined time T 1  stored in the data storage section  114  and determines whether or not the counter value passes the predetermined time T 1 . The CPU  111  repeats processing of step S 14  until the time T 1  passes. Time T 1  is set in advance (e.g., by experiment) to a time to cause retracting force of the return spring  124  to become weak to the point where no abnormal noise is emitted from the clutch or the like of the power transmission mechanism  125 . More specifically, time T 1  is set so that a period (period likely to cause abnormal noise) in which the retraction speed of the belt  31  by the return spring  124  is greater than the rotating speed of the motor  121  falls within a short period of an initial motor driving period. 
     In the following step S 15 , the CPU  111  causes the motor  121  to start retracting the belt  31 . Specifically, the CPU  111  reads out a control parameter from, for example, a table stored in the data storage section  114 , depending on the situation. Then the CPU  111  generates a PWM (Pulse Width Modulation) signal having a predetermined duty ratio in accordance with the control parameter. The CPU  111  outputs the PWM signal and a control signal for specifying the rotational direction of the motor  121  to the motor driver  112 . The motor driver  112  receiving these signals creates a drive voltage by regulating the supply voltage with the PWM signal. Then the motor driver  112  applies the drive voltage to the motor  121 . This causes the motor  121  to rotate at speeds based on the duty ratio of the drive voltage, causing the belt  31  to be retracted onto the spool  123 . This retraction processing ends, for example, when the belt  31  is completely retracted. 
     The processing steps in  FIG. 4  end when the processing steps in step S 15  are terminated. 
     According to a series of the processing steps, if the buckle  35  is released by a user at, for example, timing t 1  as shown in  FIG. 5 , the retraction of the belt  31  by the return spring  124  is started, as shown in Line L 11  in  FIG. 5 . When time T 1  passes after the beginning (timing t 1 ) of the retraction, the motor  121  is driven at timing t 2 , causing the motor  121  to perform the retraction of the belt  31  as shown in Line L 12  in  FIG. 5 . 
     The CPU  111  may read out all control parameters, for example, when a vehicle ignition key is turned on, and may store them in the register or the like of the RAM. 
     As just described above, the seatbelt retractor  10  according to an exemplary embodiment does not cause the motor  121  to be driven while the return spring  124  has retracting force strong enough to cause the abnormal noise when the motor  121  is driven. When the retracting force of the return spring  124  becomes sufficiently weak, driving the motor  121  is started. Accordingly, the seatbelt retractor  10  can suppress the abnormal noise emitted during the retraction of the belt. 
     A seatbelt apparatus, a seatbelt control apparatus, a seatbelt control method, and a method 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 . 
     In the following step S 25 , the CPU  111  uses, for example, an ELR switch  123   b  to determine whether or not the retracted amount of the belt  31  is equal to or greater than a predetermined level M 1 . Specifically, the ELR switch  123   b  is disposed so as to be switched by a cam connected to the spool  123  when the retracted amount the belt exceeds the predetermined level M 1 . Accordingly, the CPU  111  determines that the retracted amount of the belt exceeds the predetermined level M 1  when the ELR switch  123   b  is switched after, for example, the buckle  35  is released. Time T 1  and the predetermined level M 1  are determined in advance (e.g., by experiment) to the time and the retracted amount, respectively, to cause the retracting force of the return spring  124  to become weak to the point where no abnormal noise is emitted from the clutch or the like of the power transmission mechanism  125 . As just described above, by considering the retracted amount in addition to the time, determination can be made with a higher degree of accuracy as to whether or not the retracting force of the return spring  124  becomes weak to the point where no abnormal noise is generated. 
     The processing steps in step S 25  are repeated until it is determined that the retracted amount of the belt  31  exceeds the predetermined level M 1 . In step S 26 , the CPU  111  starts to cause the motor  121  to perform retraction processing for the belt  31 , like those in step S 15 . This retraction processing ends, for example, when the belt  31  is completely retracted. 
     According to a series of the processing steps, if the buckle  35  is released by a user at, for example, timing t 1  as shown in  FIG. 7 , the retraction of the belt  31  by the return spring  124  is started, as shown in Line L 11  in  FIG. 5 . Following timing t 2  when time T 1  passes after the beginning (timing t 1 ) of the retraction, at timing t 3  when the retracted amount of the belt  31  exceeds the predetermined level M 1 , the motor  121  is driven, causing the motor  121  to perform the retraction of the belt  31  as shown in Line L 12  in  FIG. 7 . 
     As just described above, by taking into consideration not only the time but also the retracted amount, the seatbelt retractor  10  according to an exemplary embodiment can determine with a higher degree of accuracy whether or not the retracting force of the return spring  124  becomes weak to the point where no abnormal noise is generated. Consequently, the seatbelt retractor  10  can more securely suppress the abnormal noise emitted during the belt retraction. 
     The order of the processing steps related to the embodiments above is not limited to the order shown in the flowcharts. Changes may be made to the order for efficiency reasons, for example. 
     The programs according to the embodiments above may be distributed in the form of computer readable recording media, such as a flexible disk, a CD-ROM (Compact Disk Read-Only Memory), a DVD (Digital Versatile Disk), and an MO (Magneto-Optical disk). In this case, the processing steps described above may be performed by installing the programs in a predetermined computer. Also, the programs according to the embodiments above may be stored in the storage unit (hard disk or the like) of a server provided on a communication network (for example the Internet or an intranet), and may be down-loaded to a local computer through, for example, superimposing on a carrier wave or may be read out from the server as needed to a local computer in which the programs are activated and executed. If part of the functions are performed by an OS (Operating System), only part of the functions other than performed by the OS may be distributed or transferred. 
     Means for implementing the functions of the ECU  111  is not limited to software, and a part or the whole of them may be implemented by dedicated hardware. 
     Depending on applications, the apparatus configuration as shown in  FIGS. 1 to 3  may be accordingly changed. 
     Any method of detecting, for example, the retracted amount, namely, any retracted amount detecting mechanism may be used. For example, in addition to the ELR switch  123   b , another switch may be provided in the circumferential vicinity of the cam, thereby determining with a higher degree of accuracy whether or not the retracted amount of the belt  31  exceeds the predetermined level. Alternatively, the CPU  111  may calculate the retracted amount from the driving amount of the motor  121  or the rotating amount of the spool  123 . 
     Although the embodiments above are described using an example where a seatbelt apparatus  30  is installed on the seat of a motor vehicle, the embodiments are not limited to a motor vehicle, and may be applied to the seats of other vehicles such as aircraft. 
     The priority application, Japanese Patent Application No. 2008-287208, 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.