JP2013159190A - Seat belt control device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a seat belt control device in which, when a behavior of a vehicle is brought into an instable state, a posture of an occupant can be kept appropriate without giving a sense of incompatibility to the occupant in accordance with a degree of instability.SOLUTION: When it is determined that a vehicle behavior is in an instable state, a seat belt control device winds webbing around a reel by supplying a current to a motor and a posture of a driver is kept by the tension thereof. In that case, an initial value of an addition term ΔECM of a supply current ECM to the motor is set to a larger value as a degree of instability in the case that the vehicle behavior is brought from a stable state into the instable state is higher (S42). Thereafter, the addition term ΔECM is multiplied by a gradual decrease coefficient RDEC iteratively, thereby gradually decreasing the addition term ΔECM and the supply current ECM (S45, S49).

Description

  The present invention relates to a seat belt control device that winds webbing using a motor.

  As a conventional control device for this type of seat belt, for example, one disclosed in Patent Document 1 is known. The seat belt includes a reel that winds up webbing and a motor that rotationally drives the reel. In this control device, when a seat belt is newly mounted, by supplying current to the motor, the motor is operated, the webbing is taken up, and the slack is removed. Further, during the traveling of the vehicle, the webbing target position is set stepwise in accordance with the traveling state at that time. For example, in a normal state where the webbing is not slack, in a G-linked state while the vehicle is accelerating or turning, a position where the occupant's posture is maintained. The target position is set to a position where it is strongly restrained.

  Further, when the traveling state of the vehicle changes to a state with a higher degree of instability, the webbing is further wound by setting the target position to a position corresponding to the traveling state after the change. At that time, the target position is gradually changed from the position before the change in the traveling state of the vehicle to the position after the change. In addition, the change time is set according to the change pattern of the running state, and the webbing take-up speed is set according to the set change time, thereby appropriately maintaining the posture of the occupant. I have to.

JP 2008-195093 A

  As described above, in this conventional control device, the webbing target position and the like are set in accordance with the traveling state of the vehicle and the change thereof. However, even if such a setting is made, there is a possibility that the occupant's posture cannot be properly maintained. For example, when the running state of the vehicle changes from the normal state to the G-linked state, when the change time of the target position is long and the webbing take-up speed is constant, the webbing tension is insufficient particularly at the beginning of the change period. As a result, the posture of the occupant cannot be properly maintained. In order to avoid this problem, for example, it is conceivable to shorten the change time of the target position. However, in that case, since the great tension of the webbing acts on the occupant abruptly, there is a great abrupt feeling and there is a possibility of giving the occupant an uncomfortable feeling.

  The present invention has been made to solve the above-described problems. When the behavior of the vehicle becomes unstable, the occupant does not give the occupant an uncomfortable feeling according to the degree of instability. It is an object of the present invention to provide a seat belt control device capable of appropriately maintaining the posture of the vehicle.

  In order to achieve the above object, the invention according to claim 1 is mounted on a vehicle V, operates when supplied with an electric current, and rotates the reel 8 to wind the webbing 5 around the reel 8. A control device 1 for a seat belt having a motor 9, and behavior determination means for determining whether or not the behavior of the vehicle V is in an unstable state including the degree of instability (hereinafter referred to as this section). In step 3) of FIG. 3 and the ECU 2 and the behavior of the vehicle V is determined to be in an unstable state, the initial value (first initial value) of the current (supply current ECM) supplied to the motor 9 is determined. The initial value setting means (ECU2, step 42 in FIG. 5, step 62 in FIG. 6) sets EINIH, the second initial value EINIM) to a larger value as the determined degree of instability of the behavior of the vehicle V is higher. When When it is determined that the behavior of the vehicle V is in an unstable state, a current is supplied to the motor 9 to wind the webbing 5 around the reel 8, and the supplied current is gradually decreased from the set initial value. Current control means (ECU 2, steps 45 and 49 in FIG. 5, steps 67 and 71 in FIG. 6) for executing current gradual reduction control.

  According to this seat belt control device, when it is determined that the behavior of the vehicle is in an unstable state, the webbing is wound around the reel by supplying current to the motor. As a result, when the behavior of the vehicle becomes unstable, the tension of the webbing is increased, and the occupant's posture is maintained by restraining the occupant with the webbing.

  Further, the current supplied to the motor at this time is gradually decreased from the initial value by the current gradually decreasing control. In this way, by starting the supply current to the motor from a larger initial value, when the occupant's posture begins to collapse immediately after the behavior of the vehicle becomes unstable, a greater webbing tension is applied to the occupant. By making it act, a passenger | crew can be restrained effectively. Thereafter, since the current supplied to the motor gradually decreases, the webbing tension does not become excessive, thereby preventing the passenger from being over-tightened and avoiding the passenger from feeling uncomfortable.

  Furthermore, since the initial value of the current supplied to the motor is set to a larger value as the degree of instability of the determined vehicle behavior is higher, the instability becomes unstable when the vehicle behavior becomes unstable. Depending on the degree, the webbing tension can be appropriately secured, and thereby the occupant's posture can be appropriately kept.

  According to a second aspect of the present invention, in the seatbelt control device 1 according to the first aspect, the behavior determining means determines the degree of instability of the behavior of the vehicle V in a stepwise manner, and the current control means is a current gradually decreasing control. Even when the instability of the behavior of the vehicle V changes to a higher level during the execution of the control, the current gradually decreasing control is continued (ECU 2, steps 63 to 67 in FIG. 6).

  According to this configuration, even when the determined degree of instability of the behavior of the vehicle changes to a higher level during execution of the current gradual decrease control, the current gradual decrease control is continued. As the degree of instability of vehicle behavior increases, the webbing tension required to restrain the occupant increases. However, when the degree of instability becomes high during the current gradual reduction control, the webbing tension according to the degree of instability before the change is ensured by supplying the current. For this reason, for example, when switching from current gradual reduction control to control for increasing current, the webbing tension may become excessive.

  Therefore, even in the above situation, by continuing the current gradual reduction control, it is possible to prevent the occupant from being overtightened due to excessive webbing tension and to prevent the occupant from feeling uncomfortable. Further, by continuing the current gradually decreasing control, the webbing is further wound and the webbing tension is further increased, so that the occupant's posture can be appropriately maintained.

  According to a third aspect of the present invention, in the seatbelt control device 1 according to the second aspect, the current control means is after the level of instability of the behavior of the vehicle V has changed to a higher stage than before the change. In the current gradual decrease control, the current gradual decrease degree (gradual decrease coefficient RDEC) is reduced (step 66 in FIG. 6).

  According to this configuration, during the execution of the current gradual reduction control, after the degree of instability of the behavior of the vehicle changes to a higher stage, the current gradual reduction degree in the current gradual reduction control is made smaller than before the change. As a result, the posture of the occupant can be better maintained by securing a larger webbing tension.

  According to a fourth aspect of the invention, in the seatbelt control apparatus 1 according to the second or third aspect, the current control means is in a stage where the degree of instability of the behavior of the vehicle V is lower during the execution of the current gradual reduction control. When the change is made, the current gradual decrease control is terminated and the current supplied to the motor 9 is controlled to a predetermined value (basic value EREFB) smaller than that during the current gradual decrease control (steps 48 and 49 in FIG. 5, FIG. 6). Steps 70 and 71).

  According to this configuration, the current supplied to the motor is controlled to a smaller predetermined value and the webbing tension is reduced as the degree of instability of the behavior of the vehicle changes to a lower stage during the current gradually decreasing control. Therefore, the posture of the occupant can be appropriately maintained while preventing the occupant from being overtightened.

1 is a side view schematically showing a vehicle seat belt to which the present invention is applied together with a driver's seat and a driver. It is a figure showing a seat belt and its control device roughly. It is a flowchart which shows the control process of the motor performed by a control apparatus. It is a flowchart which shows the attitude | position holding control process which hold | maintains a passenger | crew's attitude | position. It is a flowchart which shows the high current control process among attitude | position maintenance control processes. It is a flowchart which shows the medium current control process among attitude | position maintenance control processes. It is a flowchart which shows the low electric current control process among attitude | position maintenance control processes. It is a figure which shows the change of the supply current to the motor set by the high current control process and the high current control process.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the drawings. The seat belt 3 shown in FIG. 1 is of a so-called three-point type, and includes a webbing 5 for restraining the driver DR to the driver's seat SE and a retractor 6 for winding the webbing 5. The retractor 6 is attached to the lower part of the center pillar CP on the right side of the vehicle V. The webbing 5 extends upward from the retractor 6 and is passed through a through anchor TA attached to the upper portion of the center pillar CP. The front end portion of the webbing 5 is connected to the lower portion of the center pillar CP and an outer anchor (not shown). It is fixed through. The webbing 5 extends in the vertical direction along the center pillar CP in a non-wearing state where the webbing 5 is not applied to the driver DR.

  The webbing 5 is provided with a tongue plate TP between the through anchor TA and the outer anchor. The tongue plate TP is slidable in the length direction of the webbing 5 and is detachable from the buckle BU. The buckle BU is fixed to the front floor FF of the vehicle V, and is disposed near the passenger seat near the driver seat SE. In the seat belt 3 having the above configuration, the driver DR seated on the driver's seat SE pulls out the webbing 5 from the retractor 6 and engages the tongue plate TP with the buckle BU, whereby the webbing 5 is hung on the driver DR. . In this wearing state, the driver DR is restrained by the driver's seat SE by the webbing 5.

  As shown in FIG. 2, the retractor 6 includes a frame 7 fixed to the center pillar CP, a reel 8 around which the webbing 5 is wound, a motor 9 for rotating the reel 8, and the like. The reel 8 is rotatably supported by the frame 7 and is urged by a return spring (not shown) in a direction in which the webbing 5 is wound (hereinafter referred to as “winding direction”). By urging by the return spring, the webbing 5 is wound around the reel 8 after the seat belt 3 is released and stored in the center pillar CP.

  Further, the shaft portion 8 a of the reel 8 is connected to the output shaft 9 a of the motor 9 via the power transmission mechanism 10. The motor 9 is composed of, for example, a DC motor, converts the supplied current into motive power, and outputs it from the output shaft 9a. The power transmission mechanism 10 includes a mechanical clutch, a planetary gear device (none of which are shown), and the like.

  With the above configuration, when the motor 9 rotates in the forward direction, the output shaft 9a of the motor 9 is connected to the shaft portion 8a of the reel 8 by the clutch, and the power of the motor 9 is generated by the planetary gear unit of the power transmission mechanism 10. It is transmitted to the reel 8 in a decelerated state. Thereby, the reel 8 is rotationally driven in the winding direction. On the other hand, when the motor 9 rotates in the reverse direction, the output shaft 9a and the shaft portion 8a are blocked by the clutch.

  The retractor 6 is provided with a rotation angle sensor 21. The rotation angle sensor 21 has a plurality of magnetic poles formed at equal intervals along the circumferential direction, and is arranged in the vicinity of a magnetic disk (not shown) that rotates integrally with the reel 8 and the outer peripheral edge of the magnetic disk. A pair of Hall elements (not shown) are provided, and a pulse signal is output to the ECU 2 at every predetermined angle as the reel 8 rotates.

  The vehicle V is provided with a buckle switch 22. The buckle switch 22 outputs an ON signal to the ECU 2 when the tongue plate TP of the webbing 5 is engaged with the buckle BU, that is, when the seat belt 3 is attached.

  The ECU 2 is composed of a microcomputer including a CPU, a RAM, a ROM, an I / O interface (all not shown), and the like. The ECU 2 executes various arithmetic processes based on the control program stored in the ROM in accordance with the detection signal of the rotation angle sensor 21 and the output signal from the buckle switch 22 described above. In the present embodiment, the ECU 2 corresponds to behavior determination means, initial value setting means, and current control means.

  Next, the control process of the seat belt 3 according to the embodiment of the present invention will be described with reference to FIGS. In this control process, when the behavior of the vehicle V (hereinafter referred to as “vehicle behavior”) becomes unstable, the webbing 5 is wound up by controlling the supply current ECM supplied to the motor 9, and the driver DR The posture is maintained. This process is executed every predetermined time.

  In this process, first, in step 1 (illustrated as “S1”, the same applies hereinafter), it is determined whether or not the output signal from the buckle switch 22 is ON. If the answer is NO and the seat belt 3 is not worn, in step 2, an attitude retention control flag F_CON, which will be described later, is set to “0”, and this process ends.

On the other hand, when the answer to step 1 is YES and the seatbelt 3 is worn, in step 3, a determination process for the degree of instability of the vehicle behavior is executed. This determination process of the degree of instability is to determine whether or not the vehicle behavior is in an unstable state, including the degree of instability. In this process, it is determined whether or not the following conditions (1a) to (3) are satisfied, and it is determined that the vehicle behavior is in an unstable state when at least one of these conditions is satisfied. To do.
(1a) A collision prevention device (not shown) that forcibly puts a braking device (not shown) into a braking state when the distance from the vehicle V to the obstacle ahead is less than a predetermined value has been activated. (2b) The brake assist device that amplifies the pedal depression force when the brake pedal (not shown) is depressed suddenly is activated (1c) The yaw rate of the vehicle V detected by the yaw rate sensor (not shown) It is greater than or equal to a predetermined value (2a) The longitudinal acceleration of the vehicle V detected by a longitudinal acceleration sensor (not shown) is greater than or equal to a predetermined value (2b) detected by a lateral acceleration sensor (not shown) (3) The number of pulse signals output from the rotation angle sensor 21 in the processing cycle from the previous time to the current time (Webin) 5 represents the withdrawal of) that is equal to or greater than a predetermined value

  Further, the degree of instability of the vehicle behavior is determined step by step based on the determination result. Specifically, when at least one of the above conditions (1a) to (1c) is satisfied, it is determined that the vehicle behavior is in the first stage having the highest degree of instability. In order to express, the instability degree flag F_PRECR is set to “1”.

  Further, when none of the conditions (1a) to (1c) is satisfied and at least one of the conditions (2a) and (2b) is satisfied, the second degree of instability of the vehicle behavior is medium. In order to determine that it is in the stage and to indicate that, the instability degree flag F_PRECR is set to “2”.

  When none of the conditions (1a) to (2b) is satisfied and the condition (3) is satisfied, it is determined that the degree of instability of the vehicle behavior is in the third stage, and that In order to express the above, the instability degree flag F_PRECR is set to “3”.

  On the other hand, when none of the conditions (1a) to (3) is satisfied, the instability degree flag F_PRECR is set to “0”.

  In step 4 following step 3, it is determined whether or not an attitude holding control flag F_CON described later is “0”. If the answer is YES and the posture holding control for holding the posture of the driver DR is not executed, it is determined in step 5 whether or not the instability degree flag F_PRECR set in step 3 is “1”. Determine. If the answer to this question is YES and the vehicle behavior changes from the stable state to the unstable state, and the instability at that time is the first stage, the attitude holding control flag F_CON is set to “1” (step 6). ) After that, posture holding control to be described later is executed (step 11), and this process ends.

  On the other hand, if the answer to step 5 is NO, it is determined in step 7 whether or not the instability degree flag F_PRECR is “2”. If the answer to this question is YES and the vehicle behavior changes from the stable state to the unstable state and the degree of instability at that time is the second stage, the posture holding control flag F_CON is set to “2” (step 8) Then, go to step 11 above.

  On the other hand, when the answer to step 7 is NO, it is determined in step 9 whether or not the instability degree flag F_PRECR is “3”. When the answer is YES, the vehicle behavior changes from the stable state to the unstable state, and when the degree of instability at that time is the third stage, the posture holding control flag F_CON is set to “3” (step 10). Then, the process proceeds to step 11 above. On the other hand, if the answer to step 9 is NO and the vehicle behavior is still in a stable state, the process is terminated as it is.

  On the other hand, if the answer to step 4 is NO and the posture holding control is being executed, the steps 5 to 8 are skipped, the process proceeds to the step 11 and the posture holding control is continuously executed.

  Next, with reference to FIG. 4, the posture holding control executed in step 11 of FIG. 3 will be described. In this process, first, in step 21, it is determined whether or not the attitude holding control flag F_CON is “1”. If the answer is YES and the degree of instability when the vehicle behavior changes from the stable state to the unstable state is the first stage, in step 22, the high current control for controlling the supply current ECM to the motor 9 to be relatively high. To finish this processing.

  On the other hand, when the answer to step 21 is NO, it is determined in step 23 whether or not the attitude holding control flag F_CON is “2”. If the answer is YES and the degree of instability when the vehicle behavior changes from the stable state to the unstable state is the second stage, in step 24, the medium current control for controlling the supply current ECM to the motor 9 to a medium level. To finish this processing.

  On the other hand, if the answer to step 23 is NO and the degree of instability when the vehicle behavior changes from the stable state to the unstable state is the third stage, in step 25, the supply current ECM to the motor 9 is relatively low. The low current control to be controlled is executed, and this process is terminated.

  Next, the above-described high current control process will be described with reference to FIG. In this process, first, in step 41, it is determined whether or not the previous posture holding control flag F_CONZ is “1”. If the answer is NO and immediately after the start of the high current control, the addition term ΔECM used to calculate the supply current ECM to the motor 9 is set to a relatively large predetermined first initial value EINIH (for example, 17A).

  On the other hand, if the answer to step 41 is YES and not immediately after the start of the high current control, it is determined in step 43 whether or not the instability degree flag F_PRECR is “1” or “2”. When the answer is YES and the degree of instability of the vehicle behavior is in the first stage, or when the vehicle behavior changes to the middle second stage during high current control, a gradually decreasing coefficient for gradually decreasing the supply current ECM to the motor 9 RDEC is set to a first predetermined value RREF1 (eg, 0.4) smaller than value 1 (step 44). Next, the current addition term ΔECM is calculated by multiplying the previous addition term ΔECM by this gradually decreasing coefficient RDEC (step 45).

  The addition term ΔECM calculated as described above is set to the first initial value EINIH at the start of the high current control, and thereafter gradually decreases by being repeatedly multiplied by the gradually decreasing coefficient RDEC (see FIG. 8).

  In step 49 following step 42 or 45, the calculated addition term ΔECM is added to a predetermined basic value EREFB (for example, 3A), thereby calculating the supply current ECM to the motor 9, and the present process is terminated.

  On the other hand, when the answer to step 43 is NO, it is determined in step 46 whether or not the instability degree flag F_PRECR is “3”. If the answer is YES and the high degree of instability of the vehicle behavior changes to the third stage during the high current control, the elapsed time after the instability changes to the third stage is increased in step 47. It is determined whether the timer value TMM to be counted is equal to or longer than a predetermined time TREF (for example, 2 s). When this answer is NO, the motor 9 is reversely rotated (step 50). As described above, when the motor 9 is reversely rotated, the output shaft 9a of the motor 9 and the shaft portion 8a of the reel 8 are blocked by the clutch.

  On the other hand, if the answer to step 47 is YES and the predetermined time TREF has elapsed after the degree of instability of the vehicle behavior has changed to the third stage, the reverse rotation of the motor 9 is terminated, and in step 48, the addition term ΔECM Is set to 0, and the flow proceeds to step 49. As a result, the supply current ECM to the motor 9 is set to the basic value EREFB.

  On the other hand, when the answer to step 46 is NO and the degree of instability flag F_PRECR is “0”, that is, when the vehicle behavior returns from the unstable state to the stable state, the high current control is terminated and the posture is maintained. The control flag F_CON is reset to “0” (step 51), the supply current ECM to the motor 9 is set to 0 (step 52), and the motor 9 is stopped.

  Next, the medium current control process executed in step 24 of FIG. 4 will be described with reference to FIG. In this process, first, in step 61, it is determined whether or not the previous posture holding control flag F_CONZ is “2”. If the answer is NO and immediately after the start of the medium current control, the addition term ΔECM is set to a predetermined second initial value EINIM (for example, 12A) smaller than the first initial value EINIH for high current control.

  On the other hand, if the answer to step 61 is YES, not immediately after the start of medium current control, it is determined in step 63 whether or not the instability degree flag F_PRECR is “2”. If the answer is YES and the degree of instability of the vehicle behavior is in the second stage, the gradual decrease coefficient RDEC is set to the first predetermined value RREF1 (step 64). Next, the current addition term ΔECM is calculated by multiplying the previous addition term ΔECM by this gradually decreasing coefficient RDEC (step 67).

  On the other hand, when the answer to step 63 is NO, it is determined in step 65 whether or not an instability degree flag F_PRECR is “1”. If the answer is YES and the instability of the vehicle behavior changes to the first stage during the medium current control, the gradual decrease coefficient RDEC is set to a second predetermined value that is smaller than the value 1 and larger than the first predetermined value RREF1. A value RREF2 (for example, 1.4) is set (step 66), and the current addition term ΔECM is calculated (step 67).

  The addition term ΔECM calculated as described above is set to the second initial value EINIM that is smaller than that in the case of the high current control at the start of the medium current control, and thereafter, the gradual decrease coefficient RDEC is repeatedly multiplied, It gradually decreases and becomes smaller as a whole than in the case of high current control (see FIG. 8). Further, when the instability of the vehicle behavior is changed to the first stage during the middle current control, the gradually decreasing coefficient RDEC is switched from the first predetermined value RREF1 to the larger second predetermined value RREF2, thereby adding the term. ΔECM gradually decreases.

  In step 71 following step 62 or 67, the calculated addition term ΔECM is added to the basic value EREFB to calculate the supply current ECM to the motor 9, and this process is terminated.

  On the other hand, if the answer to step 65 is NO, it is determined in step 68 whether or not an instability degree flag F_PRECR is “3”. If the answer is YES and the instability of the vehicle behavior changes to the third stage during the medium current control, it is determined in step 69 whether or not the timer value TMM is equal to or greater than the predetermined time TREF. When this answer is NO, the motor 9 is reversely rotated (step 72).

  On the other hand, if the answer to step 69 is YES and the predetermined time TREF has elapsed since the degree of instability of the vehicle behavior has changed to the third stage, the reverse rotation of the motor 9 is terminated, and in step 70, the addition term ΔECM Is set to 0, and the flow proceeds to step 71. As a result, the supply current ECM to the motor 9 is set to the basic value EREFB.

  On the other hand, if the answer to step 68 is NO and the vehicle behavior returns from the unstable state to the stable state, the attitude maintaining control flag F_CON is reset to “0”, assuming that the medium current control is ended (step 73). At the same time, the supply current ECM to the motor 9 is set to 0 (step 74), and the motor 9 is stopped.

  FIG. 8 shows an example of the addition term ΔECM of the supply current ECM to the motor 9 set by the high current control and the medium current control described so far. In this example, at time t0, the vehicle behavior changes from the stable state to the unstable state, and accordingly, high current control or medium current control is started.

  In the case of high current control, as shown in the upper curve with a dot ●, at the start (t0), the addition term ΔECM is set to the first initial value EINIH (step 42). Thereafter, the addition term ΔECM is gradually decreased by repeatedly multiplying the first predetermined value RREF1 less than the value 1 as the gradual decrease coefficient RDEC (steps 44 and 45), and converges to the value 0 as time passes. Further, since the first initial value EINIH is larger than the second initial value EINIIM in the case of the medium current control, the addition term ΔECM and the supply current ECM as a whole become larger than in the case of the medium current control.

  Even when the instability of the vehicle behavior changes from the first stage to the second stage during the high current control, the gradual decrease coefficient RDEC is maintained at the first predetermined value RREF1 (steps 43 and 44). The addition term ΔECM is set to the same value as that when the degree of instability does not change.

  In the case of medium current control, as shown in the lower curve with a ▲ mark, at the start (t0), the addition term ΔECM is set to a second initial value EINIIM that is smaller than the first initial value EINIH. (Step 62). Thereafter, the addition term ΔECM is gradually decreased by repeatedly multiplying the first predetermined value RREF1 as the gradual decrease coefficient RDEC (steps 64 and 67), and converges to the value 0 as time passes. As a result, the addition term ΔECM and the supply current ECM as a whole are smaller than in the case of high current control.

  Further, when the degree of instability of the vehicle behavior changes from the second stage to the first stage during the middle current control (t1), the gradual decrease coefficient RDEC is changed from the first predetermined value RREF2 to a larger second predetermined value RREF2. By switching (steps 64 and 66 in FIG. 6), the degree of gradual decrease of the addition term ΔECM becomes small as shown by the curve with the point ▪.

  Next, the low current control process executed in step 25 of FIG. 4 will be described with reference to FIG. In this process, first, in step 81, it is determined whether or not the instability degree flag F_PRECR is “3”. If the answer is YES and the degree of instability of the vehicle behavior is in the third stage, in step 82, the supply current ECM to the motor 9 is set to the basic value EREFB, and this process is terminated.

  On the other hand, when the answer to step 81 is NO, it is determined in step 83 whether or not an instability degree flag F_PRECR is “2”. If the answer is YES and the instability of the vehicle behavior changes to the second stage during the low current control, in step 84, the supply current ECM to the motor 9 is set for the second stage which is larger than the basic value EREFB. The predetermined current EREFM (for example, 5A) is set, and this process is terminated.

  On the other hand, when the answer to step 83 is NO, it is determined in step 85 whether or not an instability degree flag F_PRECR is “1”. If the answer is YES and the instability of the vehicle behavior changes to the first stage during the low current control, the supply current ECM to the motor 9 is changed to the predetermined current EREFM for the second stage in step 86. Is set to a predetermined current EREFH (for example, 15 A) for the first stage that is larger than that, and this processing is terminated.

  On the other hand, if the answer to step 85 is NO and the degree of instability flag F_PRECR is “0”, that is, if the vehicle behavior returns from an unstable state to a stable state, the low current control is terminated and the posture is maintained. The control flag F_CON is reset to “0” (step 87), the supply current ECM to the motor 9 is set to 0 (step 88), and the motor 9 is stopped.

  As described above, according to the present embodiment, when the vehicle behavior is in an unstable state, the posture holding control for winding the webbing 5 around the reel 8 is executed (step 11 in FIG. 3). As a result, when the vehicle behavior is in an unstable state, the posture of the driver DR is adjusted by pulling the upper body of the driver DR that is about to move forward or left and right toward the driver's seat SE with the tension of the webbing 5. Can be held.

  Further, when the vehicle behavior becomes unstable, the initial value of the addition term ΔECM added to the basic value EREFB of the supply current ECM to the motor 9 is set to the first initial value EINIH in the high current control (FIG. 5). In step 42), the medium current control is set to the second initial value EINIM (step 62 in FIG. 6), so that the driver DR can be appropriately restrained immediately after the vehicle behavior becomes unstable. Thereafter, the addition term ΔECM and the decrease coefficient RDEC are repeatedly multiplied to gradually reduce the addition term ΔECM and the supply current ECM (steps 45 and 49 in FIG. 5 and steps 67 and 71 in FIG. 6). Does not become excessive, thereby preventing the driver DR from being tightened excessively and avoiding the driver DR from feeling uncomfortable.

  Further, in the high current control, compared with the case of the medium current control, the initial value of the addition term ΔECM is set to a larger value (first initial value EINIH> second initial value EINIM), and the supply current ECM is set as a whole. Since the larger value is set (FIG. 8), the tension of the large webbing 5 corresponding to the high degree of instability can be appropriately secured, and thereby the posture of the driver DR can be appropriately retained.

  Further, during the middle current control, even after the degree of instability of the vehicle behavior changes from the second stage to the higher first stage, the addition term ΔECM is continuously multiplied by the gradual decrease coefficient RDEC (steps 63 to 67 in FIG. 6). Thus, the gradual decrease of the supply current ECM to the motor 9 is continued, so that the posture of the driver DR can be appropriately maintained by the tension of the webbing 5, and the driver DR is excessively tightened due to the excessive tension of the webbing 5. This can prevent the driver DR from feeling uncomfortable.

  In this case, since the gradual decrease coefficient RDEC is switched from the first predetermined value RREF2 to the larger second predetermined value RREF2 (steps 64 and 66 in FIG. 6), in response to the degree of instability changing to a higher stage, The tension of the large webbing 5 can be ensured, and the posture of the driver DR can be better maintained.

  Further, when the instability of the vehicle behavior is changed to the third stage during the high current control or the middle current control, the tension of the webbing 5 is temporarily reduced by reversing the motor 9 and the motor 9 9 is set to the basic value EREFB and the tension of the webbing 5 is increased again (steps 47 to 50 in FIG. 5 and steps 69 to 72 in FIG. 6), so that the driver DR is prevented from being overtightened. However, the posture of the driver DR can be appropriately maintained.

  In addition, this invention can be implemented in various aspects, without being limited to the described embodiment. For example, in the embodiment, the gradual decrease of the supply current ECM to the motor 9 is performed by repeatedly multiplying the addition term ΔECM by the gradual decrease coefficient RDEC, but it can be performed by other appropriate methods. For example, in accordance with the number of gradual decreases in the supply current ECM, the gradual decrease coefficient is set in advance so as to decrease as the number of gradual decrease increases, and the gradual decrease coefficient obtained in accordance with the actual number of gradual decrease is set as the initial value of the addition term ΔECM May be multiplied. Alternatively, a subtraction term or a constant subtraction term set according to the number of gradual reductions may be subtracted from the initial value of the addition term ΔECM every processing cycle. Alternatively, a map that preliminarily defines the relationship between the number of gradual reductions and the supply current ECM as described above may be used.

  In the embodiment, whether or not the vehicle behavior is in an unstable state and the degree of instability are determined based on the above-described conditions (1a) to (3). In addition to these conditions, Alternatively, other suitable conditions may be used.

  In the embodiment, the basic value EREFB of the supply current ECM to the motor 9 is a fixed value, but instead, for example, the amount of webbing 5 drawn (rotation angle sensor 21) in the processing cycle from the previous time to this time. May be calculated at any time according to the number of output pulses. Thereby, the tension of the webbing 5 can be appropriately ensured according to the degree of collapse of the posture of the driver DR. Similarly, the first and second initial values EINIH and EINIM may be calculated according to the withdrawal amount of the webbing 5 when the vehicle behavior becomes unstable.

  The embodiment is an example of a seat belt for a driver's seat of a vehicle, but the present invention may be applied to a seat belt for a passenger seat or a rear seat. In addition, the seat belt is a three-point system in the embodiment, but a two-point system or a four-point system may be used. In addition, it is possible to appropriately change the detailed configuration within the scope of the gist of the present invention.

V vehicle 1 control device 2 ECU (behavior determination means, initial value setting means, current control means)
3 Seat belt 5 Webbing 8 Reel 9 Motor ECM Supply current (current supplied to the motor)
EINIH first initial value (initial value)
EINIM second initial value (initial value)
RDEC gradual decrease coefficient (degree of gradual decrease in supply current)
EREFB basic value (predetermined value)

Claims (4)

A control device for a seat belt having a motor mounted on a vehicle, activated by supplying electric current, and winding a webbing on the reel by rotating the reel,
Behavior determining means for determining whether or not the behavior of the vehicle is in an unstable state, including the degree of instability;
When it is determined that the behavior of the vehicle is in an unstable state, the initial value of the current supplied to the motor is set to a larger value as the degree of instability of the determined behavior of the vehicle is higher. Initial value setting means;
When it is determined that the behavior of the vehicle is in an unstable state, a current is supplied to the motor to wind the webbing onto the reel, and the supplied current is determined from the set initial value. Current control means for executing gradually decreasing current gradually decreasing control;
A control device for a seat belt, comprising: The behavior determination means determines the degree of instability of the behavior of the vehicle in stages,
The current control means continues the current gradual reduction control even when the degree of instability of the behavior of the vehicle changes to a higher stage during the execution of the current gradual reduction control. The control device for the seat belt according to 1.   The current control means, after the degree of instability of the behavior of the vehicle has changed to a higher level, makes the current gradually decreasing in the current gradually decreasing control smaller than before the change. The seat belt control device according to claim 2.   The current control means terminates the current gradual reduction control when the degree of instability of the behavior of the vehicle changes to a lower stage during execution of the current gradual reduction control, and supplies the current supplied to the motor. 4. The seat belt control apparatus according to claim 2, wherein the control is performed to a predetermined value smaller than that during the current gradual decrease control.

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