JP5069763B2 - Seat belt device - Google Patents

Description

  The present invention relates to a seat belt device for restraining an occupant seated on a seat by webbing.

In a seat belt device mounted on a vehicle, a webbing for restraining an occupant is wound around a reel in a retractor, and is pulled out from the retractor when mounted.
In recent years, a seat belt device has been devised in which the vehicle state is detected by vehicle state detection means such as an acceleration sensor, a yaw rate sensor, and a brake switch, and the webbing is pulled in by an electric motor in accordance with the vehicle state.

  In addition, in a seat belt device using this type of electric motor, if there is a failure in the vehicle state detection means itself, or the wiring or communication network between the vehicle state detection means and the controller, the webbing is taken up in an emergency. Has been devised in which a failure detection means for detecting a failure is provided, and when the failure detection means detects a failure, the webbing is wound by an electric motor. (For example, refer to Patent Document 1).

JP 2007-62673 A

  However, in this conventional seat belt device, when an abnormality in the input system such as the vehicle state detecting means is detected, strong pulling is always performed by the electric motor. There is a possibility of giving a sense of incongruity.

  Accordingly, the present invention is intended to provide a seat belt device that can reliably restrain an occupant without giving a sense of incongruity even when there is a signal abnormality in a vehicle state detection means.

The invention according to claim 1, which solves the above problem, is a reel on which webbing is wound (for example, a reel 12 in an embodiment described later) and an electric motor (for example, described later) that transmits a driving force to the reel. The electric motor 10) in the embodiment, and a clutch that receives a rotational torque that is equal to or greater than a set value in the webbing winding direction of the electric motor and maintains the electric motor and the reel in a connected state (for example, a clutch 20 in the embodiments described later). According to vehicle state detection means for detecting the vehicle state (for example, longitudinal acceleration sensor 30, lateral acceleration sensor 31, and yaw rate sensor 32 in the embodiments described later) and the vehicle state detected by the vehicle state detection means. And a control device that controls the electric motor (for example, a controller 21 in an embodiment described later). An abnormality detection means for detecting a signal abnormality from the vehicle state detection means (for example, an abnormality detection means 50 in an embodiment described later) and a signal abnormality detected by the abnormality detection means, A failure verification unit (for example, a failure verification unit 51 in an embodiment described later) for verifying whether or not the failure is caused by a failure, and the control device controls the electric motor according to the state of the vehicle. (For example, standard control means 52 in the embodiment described later) and holding control means for controlling the electric motor so as to maintain the clutch in a connected state without winding the webbing (for example, holding in the embodiment described later) Control means 53), and when the electric motor is controlled by standard control means, a signal abnormality is detected by the abnormality detection means. In this case, until the verification by the failure verification unit is completed, the control is switched to the control of the electric motor by the holding control unit, and after the failure verification by the failure verification unit, the clutch waits for a predetermined time to elapse. It is characterized by blocking.
In this case, when the abnormality of the signal from the vehicle state detection means is detected by the abnormality detection means while the electric motor is controlled by the standard control means, it is determined whether or not the signal abnormality is due to a failure. It is verified by the verification means. During the verification by the failure verification means, the control of the electric motor is switched from the control by the standard control means to the control by the holding control means. During this time, although the webbing is not actively pulled by the electric motor, the reel and the electric motor are connected via the clutch, so that resistance is given to the webbing drawer. Further, after the failure is verified by the failure verification means, the clutch is disengaged after a lapse of a predetermined time that should have ended even in an emergency state.

According to a second aspect of the present invention, in the seat belt device according to the first aspect, a winding amount detection means (for example, a rotation sensor 11 in an embodiment described later) for detecting a webbing winding amount of the reel, and a tongue A buckle switch (for example, a buckle switch 33 in a later-described embodiment) that detects that a plate (for example, a tongue plate 8 in a later-described embodiment) is engaged with a buckle (for example, a buckle 9 in a later-described embodiment). The control device further includes second abnormality detection means (for example, second abnormality detection means 54 in an embodiment described later) for detecting a signal abnormality of the winding amount detection means, First asymptotic control means for making the current command value of the electric motor asymptotically approach the first fixed command value (for example, first asymptotic in an embodiment described later) Control means 55) and second asymptotic control means for making the current command value of the electric motor asymptotically approach a second fixed command value smaller than the first fixed command value (for example, second Asymptotic control means 56), and when the electric motor is controlled by the standard control means and the signal abnormality is detected by the second abnormality detection means, the buckle switch is engaged. When detected, the control is switched to the control of the electric motor by the first asymptotic control means, and when the buckle switch detects the disengaged state, the control is switched to the control of the electric motor by the second asymptotic control means. To do.
In this case, when the signal abnormality of the winding amount detection means is detected by the second abnormality detection means while the electric motor is controlled by the standard control means, the engagement state of the tongue plate and the buckle is determined through the buckle switch. Determined. When the buckle switch detects the engaged state, the control of the electric motor is switched to the control by the first asymptotic control means, and the electric motor is controlled so as to approach the relatively large first fixed command value. . Further, when the buckle switch detects the non-engaged state, the control of the electric motor is switched to the control by the second asymptotic control means, and the second fixed command is smaller than the first fixed command value. Controlled to be asymptotic to the value.

  According to the first aspect of the present invention, when the electric motor is controlled by the standard control means, the failure is verified when the abnormality of the signal from the vehicle state detection means is detected by the abnormality detection means. Since the electric motor is controlled by the holding control means during the period up to and after the predetermined time after verification, the occupant can be reliably restrained by the pull-out resistance on the electric motor side in an emergency state. When the vehicle is not in a state, the passenger is not excessively restrained by the webbing, so that the passenger does not feel uncomfortable.

  According to the second aspect of the invention, when the electric motor is controlled by the standard control means, the buckle is engaged when the signal abnormality of the winding amount detection means is detected by the second abnormality detection means. When it is necessary to restrain the occupant in the combined state, the electric motor is controlled so as to approach the first fixing command value, and at the time of winding when the buckle is not engaged, the second fixing smaller than that is performed. Since the electric motor is controlled so as to approach the command value, the webbing can be wound with an appropriate force according to the situation.

1 is a schematic configuration diagram of a seat belt device according to an embodiment of the present invention. It is a schematic block diagram of the retractor and controller of the seatbelt apparatus of one Embodiment of this invention. It is a schematic block diagram of the retractor of the seatbelt apparatus of one Embodiment of this invention. It is a flowchart which shows the flow of control of the seatbelt apparatus of one Embodiment of this invention. It is a flowchart which shows the flow of control of the seatbelt apparatus of one Embodiment of this invention. It is a flowchart which shows the flow of control of the seatbelt apparatus of one Embodiment of this invention.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an overall schematic configuration of a seat belt device 1 according to the present invention. In FIG. 1, reference numeral 2 denotes a seat on which an occupant 3 is seated. The seat belt device 1 of this embodiment is a so-called three-point seat belt device, and a webbing 5 is drawn upward from a retractor 4 attached to a center pillar (not shown), and the webbing 5 is supported on the upper side of the center pillar. The tip of the webbing 5 is fixed to the vehicle body floor via an outer anchor 7 near the outside of the passenger compartment of the seat 2. A tongue plate 8 is inserted between the through anchor 6 and the outer anchor 7 of the webbing 5, and the tongue plate 8 can be attached to and detached from the buckle 9 fixed to the vehicle body floor of the seat 2 on the inner side of the vehicle body. It has become.
The webbing 5 is wound around the retractor 4 in an initial state, and the occupant 3 pulls out by hand and engages the tongue plate 8 with the buckle 9, thereby restraining the chest and abdomen of the occupant 3 with respect to the seat 2. . Further, the seat belt device 1 automatically winds the webbing 5 by the electric motor 10 when the behavior of the vehicle becomes unstable.

  As shown in FIG. 2, the retractor 4 has a webbing 5 wound around a reel 12 rotatably supported by a casing (not shown), and a shaft of the reel 12 projects from one end side of the casing. The reel 12 is connected to the rotating shaft 10 a of the electric motor 10 via a power transmission mechanism 13 so as to be interlocked. The power transmission mechanism 13 decelerates the rotation of the electric motor 10 and transmits it to the reel 12. Further, the retractor 4 is provided with a winding spring (not shown) that urges the reel 12 in the webbing winding direction, and in a state where the reel 12 and the electric motor 10 are separated by a clutch 20 described later, tension by the winding spring is provided. Acts on the webbing 5.

Further, the retractor 4 is provided with a rotation sensor 11 (winding amount detection means) for detecting the rotation position of the reel 12. The rotation sensor 11 includes, for example, a magnetic disk in which different magnetic poles are alternately magnetized along the circumferential direction, and a pair of magnetic disks that rotate integrally with the reel 12 and a pair of adjacently arranged outer peripheral edges of the magnetic disk. It consists of a Hall element and a sensor circuit that processes the detection signal of the Hall element, and a pulse signal processed by the sensor circuit is output to the controller 21 (control device).
In this case, the pulse signal input from the sensor circuit to the controller 21 according to the rotation of the reel 12 is used to detect the rotation amount (rotation position), the rotation speed, the rotation direction, and the like of the reel 12. That is, the controller 21 detects the amount of rotation of the reel 12 (the amount of winding / drawing of the webbing 5) by counting the pulse signal, and calculates the change rate (frequency) of the pulse signal by calculating the change rate (frequency) of the pulse signal. The rotation speed (winding / drawing speed of the webbing 5) is obtained, and the rotation direction of the reel 12 is detected by comparing the rising edges of the waveforms of both pulse signals.

FIG. 3 shows a specific configuration of the power transmission mechanism 13.
In the power transmission mechanism 13, the sun gear 14 is integrally coupled to the drive input external teeth 15, and the carrier 17 that supports the plurality of planetary gears 16 is coupled to the shaft of the reel 12. A plurality of ratchet teeth (not shown) are formed on the outer peripheral side of the ring gear 18 meshed with the planetary gear 16, and these ratchet teeth constitute a part of the clutch 20. The clutch 20 appropriately disconnects the power transmission system between the electric motor 10 and the reel 12 by controlling the driving force of the electric motor 10 by the controller 21.

  The motor-side power transmission system 22 of the power transmission mechanism 13 is capable of rotating coaxially and integrally with the first connect gear 23 having a small diameter that is always meshed with the external teeth 15 that are integral with the sun gear 14. A large-diameter second connect gear 24 provided, and first and second idler gears 26 that are between the second connect gear 24 and the motor gear 25 (integrated with the rotating shaft 10a of the electric motor 10) and are always meshed so that power can be transmitted. , 27. The driving force in the forward direction of the electric motor 10 is transmitted to the second and first connect gears 24 and 23 through the gears 25, 27 and 26, and further transmitted to the sun gear 14 through the external teeth 15, and then the planetary gear 16. And transmitted to the reel 12 through the carrier 17. The driving force in the forward direction of the electric motor 10 rotates the reel 12 in the direction in which the webbing 5 is pulled. However, the driving force transmitted from the sun gear 14 to the planetary gear 16 is all transmitted to the carrier 17 side as described above when the ring gear 18 is fixed. However, when the ring gear 14 is free to rotate, the planetary gear is transmitted. The ring gear 18 is idled by 16 rotations. The clutch 20 performs on / off operation of transmission of the motor driving force to the reel 12 (carrier 17) by controlling the locking and unlocking of the rotation of the ring gear 14.

  The clutch 20 includes the ratchet teeth provided on the outer periphery of the ring gear 18 and a pawl (not shown) that is rotatably supported by a casing (not shown) and whose front end portion can mesh with the ratchet teeth. The engagement with the ratchet teeth is triggered by the rotation of the motor 10 in the forward rotation direction, and the meshing with the ratchet teeth is released by the rotation of the electric motor 10 in the reverse rotation direction. Therefore, once the electric motor 10 is driven in the forward direction, the clutch 20 locks the ring gear 18 and maintains the electric motor 10 and the reel 12 in the connected state, and then the electric motor 10 is driven in the reverse direction. Then, the lock of the ring gear 18 is released, and the electric motor 10 and the reel 12 are brought into a disconnected state.

Incidentally, on the input side of the controller 21, as shown in FIG. 2, in addition to the rotation sensor 11, a longitudinal acceleration sensor 30 for detecting the longitudinal acceleration of the vehicle, and a lateral acceleration for detecting the lateral acceleration of the vehicle. A sensor 31, a yaw rate sensor 32 that detects angular acceleration in the yaw direction of the vehicle, a buckle switch 33 that detects attachment / detachment of the tongue plate 8 to / from the buckle 9, a current sensor 40 that detects current supplied to the electric motor 10, and the like are connected. Has been. In addition, the controller 21 transmits and receives signals to and from controllers of other systems such as a VSA (Vehicle Stability Assist) system 34 through an in-vehicle communication network.
In this embodiment, various sensors such as the longitudinal acceleration sensor 30, the lateral acceleration sensor 31, and the yaw rate sensor 32 and other systems such as the VSA system 34 that transmits information through the in-vehicle communication network detect the state of the vehicle. Functions as vehicle state detection means.

  The controller 21 also detects abnormalities in signals input from the longitudinal acceleration sensor 30, the lateral acceleration sensor 31, the yaw rate sensor 32, and other systems (for example, an input of an impossible signal patterner or a different signal from the same type of sensor). Input) and a failure verification unit 51 that verifies whether the abnormality signal is caused by a failure of a device, a signal line, a communication network or the like when the abnormality detection unit 50 detects an abnormality signal. And a standard control means 52 that controls the energization current of the electric motor 10 according to the state of the vehicle when the input signal is normal, and a low current that can maintain the clutch 20 in the connected state without winding the webbing 5. Holding control means 53 for energizing the electric motor 10.

  The failure verification means 51, for example, examines a signal packet sent from a sensor that detects the vehicle state at a predetermined cycle, and determines that there is a signal abnormality (fixed) when the content of the signal packet does not change for a predetermined time or more. .

When there is no signal abnormality in the input system of the controller 21, the controller 21 controls energization of the electric motor 10 by the standard control means 52. Specifically, for example, when the vehicle suddenly decelerates in an emergency or is greatly shaken in the lateral direction, the controller 21 is electrically powered by the standard control means 52 so as to rapidly wind the webbing 5 to the target position. The motor 10 is energized and controlled.
When the electric motor 10 is controlled by the standard control means 52 and the abnormality detection means 50 detects a signal abnormality in the input system of the controller 21 (abnormality in the vehicle state detection signal), the controller 21 At the same time as the failure verification by the failure verification means 51 is started, the control of the electric motor 10 is switched from the control by the standard control means 52 to the control by the holding control means 53. Further, after the failure is verified by the failure verification means 51, the controller 21 controls the electric motor 10 by the holding control means 53 for a predetermined time (a predetermined time during which the emergency state should end even in an emergency). The electric motor 10 is controlled so that the clutch 20 is disengaged thereafter.

  Further, the controller 21 controls the second abnormality detecting means 54 for detecting the signal abnormality of the rotation sensor 11 and the current command value for the electric motor 10 so as to gradually approach the first fixed command value D1. Asymptotic control means 55 and second asymptotic control means 56 for controlling the current command value for the electric motor 10 to gradually approach a second fixed command value D2 smaller than the first fixed command value D1. ing.

  For example, the second abnormality detection unit 54 checks the pulse pattern output from the pair of Hall elements of the rotation sensor 11 described above, and if the pulse pattern is not normal, the second abnormality detection unit 54 detects a signal abnormality (an abnormality in the rotation sensor 11). ).

  Further, the controller 21 detects a signal abnormality of the rotation sensor 11 by the second abnormality detection means 54 and detects an engagement state of the tongue plate 8 and the buckle 9 by the buckle switch 33. When a signal abnormality of the rotation sensor 11 is detected, the electric motor 10 is energized and controlled by either the first asymptotic control means 55 or the second asymptotic control means 56 according to the signal of the buckle switch 33. Specifically, when the buckle switch 33 is ON (when the tongue plate 8 is engaged), the energization control of the electric motor 10 by the first asymptotic control means 55 is executed, and the buckle switch 33 is OFF. In this case (when the tongue plate 8 is not engaged), the energization control of the electric motor 10 by the second asymptotic control means 56 is executed.

Hereinafter, an example of the control by the controller 21 of the seat belt apparatus 1 will be described with reference to the flowcharts of FIGS. This example is a control example when a signal corresponding to a light collision (emergency state) is input from a longitudinal acceleration sensor or the like, for example.
In step S101 of FIG. 4, it is determined whether or not an emergency state is based on input signals from various sensors. If yes, the process proceeds to step S102, and if no, the process returns. . In step S102, the control of the electric motor 10 is started by the standard control means 52, and in step S103, whether or not there is a signal abnormality on the input side by the abnormality detection means 50 and the second abnormality detection means 54 is determined. judge. At this time, in the case of Yes, the process proceeds to step S104, and in the case of No, the process proceeds to step S105.

  In step S104, it is determined whether or not there is a signal abnormality of sensors that detect the vehicle state, that is, whether or not there is a signal abnormality of sensors other than the rotation sensor 11. Further, when the process proceeds to step S105, since there is no signal abnormality, the control of the electric motor 10 by the standard control means 52 is continued, and it is determined in step S106 whether the emergency state has been resolved or not. In step S107, the release operation is performed, and in the case of No, the process returns.

In step S104, if Yes, the process proceeds to step S108. If No, the process proceeds to a rotation sensor system failure process S300 described later.
In step S108, the control of the electric motor 10 is switched from the control by the standard control means 52 to the control by the holding control means 53. Further, in the subsequent step S109, the failure verification by the failure verification means 51 is executed. In step S110, it is determined whether or not the verification by the failure verification unit 51 has been completed. If yes, the process proceeds to step S111. If no, the control by the holding control unit 53 and verification of the failure are performed. Continue.
Then, when the verification is completed and the process proceeds to step S111, the control of the electric motor 10 by the holding control means 53 is further continued for a predetermined time, and then the process proceeds to step S107 to perform a release process.

FIG. 5 shows an example of the failure verification process in step S109.
In step S201 in the figure, the contents of a signal packet sent from the sensors for detecting the vehicle state at a predetermined cycle (for example, a cycle of 10 ms) are examined, and it is determined whether or not the previous value of the content is equal to the current value. . Here, if Yes, that is, if there is no change in content, the process proceeds to step S202. If No, that is, if there is a change in content, the process proceeds to step S203.
In step S203, the failure counter is cleared and the process returns. At this time, the counter value of the failure counter is maintained at “0”, for example, and does not increase.
In step S202, the value of the failure counter is incremented, and in subsequent step S204, it is determined whether or not the counter value of the failure counter is not less than a specified value, for example, “100” or more. At this time, in the case of Yes, the process proceeds to step S205 to determine the failure, and in the case of No, the process returns. That is, if the content of the signal packet does not change for a predetermined time or more, a failure is determined in step S205.
The above processing is executed with a predetermined time as the upper limit time. If no failure is determined even after the upper limit time is exceeded, it is determined that there is no failure.

FIG. 6 shows an example of the rotation sensor system failure process S300.
In step S301 in the figure, it is determined whether or not the buckle switch 33 is ON. If the answer is YES, that is, if the tongue plate 8 is engaged with the buckle 9, the process proceeds to step S302. No, that is, if the tongue plate 8 is disengaged, the process proceeds to step S303.

In step S302, it is determined whether or not the current command value of the electric motor 10 is larger than a first fixed command value D1 (for example, duty ratio 20). If yes in this case, the process proceeds to step S305, and No. In this case, the process proceeds to step S304.
In step S304, it is determined whether or not the current command value of the electric motor 10 is further equal to the first fixed command value D1. If yes, the process proceeds to step S306, and if no, step S307 is performed. Proceed to
In step S302 and step S304, the current command value is assigned to each case when it is larger than the first fixed command value D1 (step S305), equal (step S306), or smaller (step S307).
In step S306, since the current command value of the electric motor 10 is the first fixed command value D1, the current energization is continued, and in step S305, the current command value is decremented so as to approach the first fixed command value D1. In step S307, the current command value is incremented so as to approach the first fixed command value D1. That is, in steps S305 to S307, energization of the electric motor 10 is controlled so that the current command value gradually approaches the first fixed command value D1.

In step S303, it is determined whether or not the current command value of the electric motor 10 is larger than a second fixed command value D2 (for example, duty ratio 10). If yes in this case, the process proceeds to step S309. In this case, the process proceeds to step S308.
In step S308, it is determined whether or not the current command value of the electric motor 10 is further equal to the second fixed command value D2. If yes, the process proceeds to step S310, and if no, step S311 is performed. Proceed to
In step S303 and step S308, when the current command value is larger than the second fixed command value D2 (step S309), equal (step S310), or smaller (step S311), the distribution is made. In step S309, the current command value is decremented so as to approach the second fixed command value D2, and in step S311, the current command value is incremented so as to approach the second fixed command value D2. To do. Here, the energization of the electric motor 10 is controlled so that the current command value gradually approaches the second fixed command value D2.

  When any one of the above steps S305 to S307 and steps S309 to S311 is completed, the process proceeds to step S312 and it is determined whether or not the emergency state has been resolved in step S312. Proceed to, perform the release operation, and if No, return.

  As described above, in the seat belt device 1, when the electric motor 10 is controlled by the standard control unit 52, an abnormality in the signal from the sensors that detect the vehicle state is detected by the abnormality detection unit 50. In this case, the control of the electric motor 10 is switched to the control by the holding control means 53 until the failure is verified (confirmed) by the failure verification means 51 and for a predetermined time after the verification. Even in an emergency state, the occupant can be reliably restrained to the seat 2 by the pull-out resistance on the electric motor 10 side connected to the reel 12 side by the clutch 20.

  In the seat belt device 1, even when the abnormality detecting means 50 detects a temporary signal abnormality and there is no failure on the sensor side that detects the vehicle state, the electric motor 10 is used for the webbing 5. Since the webbing 5 is not pulled in by just holding the vehicle, the passenger 3 does not feel uncomfortable due to excessive drawing of the webbing 5.

Further, in the seat belt device 1, when the electric motor 10 is controlled by the standard control means 52 and the signal abnormality of the rotation sensor 11 is detected by the second abnormality detection means 54, the tongue plate 8 and Depending on whether or not the buckle 9 is engaged, the current command value of the electric motor 10 can be gradually brought closer to an appropriate fixed command value.
That is, in the seat belt device 1, when the tongue plate 8 and the buckle 9 are engaged, the occupant 3 needs to be restrained by the webbing 5. When the current command value is brought close to the fixed command value D1 of 1 and the engagement of the tongue plate 8 and the buckle 9 is released, the webbing 5 is simply wound up, so that the second asymptotic control means 56 The current command value can be brought close to the relatively small second fixed command value D2.

  In addition, this invention is not limited to said embodiment, A various design change is possible in the range which does not deviate from the summary.

DESCRIPTION OF SYMBOLS 1 ... Seat belt apparatus 8 ... Tongue plate 9 ... Buckle 10 ... Electric motor 11 ... Rotation sensor (winding amount detection means)
12 ... Reel 20 ... Clutch 21 ... Controller (control device)
30. Longitudinal acceleration sensor (vehicle state detection means)
31 ... Lateral acceleration sensor (vehicle state detection means)
32 ... Yaw rate sensor (vehicle state detection means)
DESCRIPTION OF SYMBOLS 33 ... Buckle switch 50 ... Abnormality detection means 51 ... Failure verification means 52 ... Standard control means 53 ... Holding | maintenance control means 54 ... 2nd abnormality detection means 55 ... 1st asymptotic control means 56 ... 2nd asymptotic control means

Claims (2)

A reel around which webbing is wound,
An electric motor for transmitting a driving force to the reel;
A clutch that receives a rotational torque equal to or greater than a set value of the webbing winding direction of the electric motor and maintains the electric motor and the reel in a connected state;
Vehicle state detection means for detecting the state of the vehicle;
A control device for controlling the electric motor in accordance with a vehicle state detected by the vehicle state detection means;
A seat belt device comprising:
An abnormality detection means for detecting a signal abnormality from the vehicle state detection means;
When a signal abnormality is detected by the abnormality detection means, failure verification means for verifying whether or not it is due to a failure is provided,
The controller is
Standard control means for controlling the electric motor in accordance with the state of the vehicle;
Holding control means for controlling the electric motor so as to maintain the clutch in a connected state without winding the webbing;
When the electric motor is controlled by the standard control means, if a signal abnormality is detected by the abnormality detection means, the verification of the electric motor by the holding control means is continued until the verification by the failure verification means is completed. Switch to control,
The seat belt device is characterized in that after the failure is verified by the failure verification means, the clutch is disengaged after a lapse of a predetermined time. A winding amount detecting means for detecting a webbing winding amount of the reel;
A buckle switch for detecting that the tongue plate is engaged with the buckle;
Is provided,
The control device further includes:
Second abnormality detection means for detecting a signal abnormality of the winding amount detection means;
First asymptotic control means for asymptotically approaching a current command value of the electric motor to a first fixed command value;
Second asymptotic control means for making the current command value of the electric motor asymptotically approach a second fixed command value smaller than the first fixed command value;
With
When a signal abnormality is detected by the second abnormality detection means when the electric motor is controlled by a standard control means,
When the buckle switch detects the engaged state, it switches to the control of the electric motor by the first asymptotic control means,
2. The seat belt device according to claim 1, wherein when the buckle switch detects a non-engaged state, the control is switched to the control of the electric motor by the second asymptotic control means.

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