JP5879330B2 - Seat belt device - Google Patents

Description

  The present invention relates to a seat belt device. In particular, the present invention relates to a seat belt device capable of executing appropriate control of a drive motor when a failure occurs in the seat belt device.

  For example, Patent Literature 1 discloses a seat belt device that winds up webbing by driving a drive motor as a seat belt device capable of executing slack removal of webbing. The seat belt device described in Patent Document 1 performs current feedback control to drive a drive motor when it is determined that the vehicle is in an emergency state such as a high possibility that the vehicle will collide with a forward object. Wind up the webbing and restrain the occupant strongly.

  The seat belt device described in Patent Document 1 determines whether or not a short-circuit failure has occurred in the seat belt device when the current feedback control is being executed. When it is determined that the seat belt device has a short circuit failure, the seat belt device described in Patent Document 1 stops the driving of the drive motor.

  By the way, there is a possibility that an open failure may occur in a general seat belt device such as the seat belt device described in Patent Document 1. For example, a connector of a drive motor is connected to the open failure by vibration of the vehicle. Also included are those that are cut or disconnected. Here, Patent Document 1 does not describe determination of whether or not an open failure has occurred. For example, when an open failure occurs in the seat belt device described in Patent Document 1, for example, it is assumed that current feedback control is continuously executed. Then, for example, when an open failure is temporarily resolved, a sudden current change may occur in the seat belt device. On the other hand, when an open failure occurs in the seat belt device described in Patent Document 1, it is assumed that driving of the drive motor is stopped, for example, in the same manner as when a short failure occurs. Then, for example, when the open failure is resolved, the seat belt device described in Patent Document 1 cannot quickly restrain the occupant.

JP 2011-105155 A

  One object of the present invention is to provide a seat belt device capable of executing appropriate control when a failure occurs in the seat belt device. Other objects of the present invention will become apparent to those skilled in the art by referring to the aspects and preferred embodiments exemplified below and the accompanying drawings.

A first aspect according to the present invention includes a belt reel for winding a webbing,
A drive motor for rotating the belt reel;
A vehicle state detector for detecting the state of the vehicle;
A trigger signal generator for generating a trigger signal for starting control of the drive motor in accordance with the state of the vehicle;
A motor control unit for controlling the drive motor in response to the trigger signal;
Have
The motor control unit determines whether an open failure related to the connection between the motor control unit and the drive motor has occurred based on the drive current value of the drive motor during the control of the drive motor. ,
When the motor control unit determines that the open failure has occurred, the motor control unit relates to a seat belt device that executes fixed duty control instead of current feedback control.

  The motor control unit executes fixed duty control instead of current feedback control when it is determined that an open failure related to the connection between the motor control unit and the drive motor has occurred during the control of the drive motor. Therefore, the seat belt device can avoid a sudden change in the drive current of the drive motor when an open failure is resolved during winding of the webbing. In addition, the seat belt device can continue the winding of the webbing when an open failure occurs during the winding of the webbing, so that the occupant can be restrained appropriately.

In a second aspect according to the present invention, in the first aspect,
The motor control unit may stop driving of the drive motor after a predetermined time has elapsed from a certain time when the fixed duty control is executed.

  The motor control unit stops driving the drive motor after a predetermined time has elapsed from a certain time when the fixed duty control is executed. Therefore, for example, even if a rotation angle sensor or the like is not provided in the seat belt device, the drive motor can take up the webbing by an appropriate amount.

In a third aspect according to the present invention, in the first or second aspect,
The motor control unit determines whether a short-circuit failure has occurred in the connection between the motor control unit and the drive motor based on the drive current value of the drive motor during the control of the drive motor. Judgment further,
The motor control unit may stop driving of the drive motor when it is determined that the short circuit failure has occurred.

  When the motor control unit determines that an open failure related to the connection between the motor control unit and the drive motor has occurred during the control of the drive motor, the motor control unit stops driving the drive motor. Therefore, the seat belt device can avoid a large current from flowing in the seat belt device.

It is a block diagram which shows the example of a structure of the seatbelt apparatus according to this invention. It is a figure which shows a part of structure of the electricity supply amount adjustment part shown by FIG. It is the figure which looked at the vehicle provided with the seatbelt apparatus according to this invention from the front. It is a disassembled perspective view of the winding apparatus shown by FIG. It is explanatory drawing of the motor drive mechanism shown by FIG. It is explanatory drawing of the contact state of the clutch mechanism shown by FIG. It is explanatory drawing of the disconnection state of the clutch mechanism shown by FIG. It is a figure which shows the equivalent circuit of the H bridge circuit shown by FIG. It is a flowchart figure which shows the operation example of the seatbelt apparatus according to this invention.

  The preferred embodiments described below are used to facilitate an understanding of the present invention. Accordingly, those skilled in the art should note that the present invention is not unduly limited by the embodiments described below.

1. Overall Configuration An example of the configuration of a seat belt device 10 according to the present invention will be described with reference to FIG. The seat belt apparatus 10 includes an ECU 100 including at least a motor control unit 110, a trigger signal generation unit 120, and a vehicle state detection unit 130. As an example, a retractor 14 and a webbing 16 including a belt reel 15 and a drive motor 31 are provided. Further prepare. In the seat belt device 10, the motor control unit 110 may control the energization amount adjustment unit 300 to supply power supplied from the power source 200 to the drive motor 31, and the shaft 15 a of the belt reel 15 may be driven by a motor. It may be connected to the drive shaft 31 a of the drive motor 31 via the mechanism 35. Further, the belt reel 15 may be provided rotatably in the frame 41.

  The ECU 100 includes, for example, a microcomputer, and includes a motor control unit 110, a trigger signal generation unit 120, and a vehicle state detection unit 130 as an example. The ECU 100 may further include, for example, a storage unit, an input / output interface unit, and the like that are not shown in addition to the motor control unit 110, the trigger signal generation unit 120, and the vehicle state detection unit 130. An input / output interface unit (not shown) can be connected to, for example, an SRS (Supplement Restraint System) unit (auxiliary restraint unit) (not shown), and the ECU 100 can input an operation signal of the SRS unit. In addition, the input / output interface unit can be connected to an in-vehicle LAN such as a CAN (Control Area Network), for example, and the ECU 100 includes a VSA (Vehicle Stability Assist) unit (vehicle behavior stabilization control unit), ACC (not shown), and ACC. The operation signal of (Adaptive Cruise Control) unit (obstacle detection device control unit) or the like can be input.

  When it is determined that the trigger signal is generated by the trigger signal generation unit 120, the motor control unit 110 controls the energization amount adjustment unit 300 to execute current feedback control. The drive motor 31 rotates the belt reel 15 and winds the webbing 16 by current feedback control so that the current value set so that a predetermined tension is applied to the webbing 16 and the drive current value of the drive motor 31 coincide. take. Specifically, the motor control unit 110 calculates a duty ratio so that the drive current value of the drive motor 31 to be fed back coincides with the set current value, and the drive motor 31 is supplied with the power supply 200 only during the duty-on period. The energization amount adjustment unit 300 is controlled to supply power. If the drive current value fed back from the energization amount adjustment unit 300 is lower than the set current value, the motor control unit 110 calculates a duty ratio higher than the current duty ratio. On the other hand, if the drive current value fed back from the energization amount adjustment unit 300 is higher than the set current value, the motor control unit 110 calculates a duty ratio lower than the current duty ratio.

  The trigger signal generation unit 120 generates a trigger signal according to the vehicle state detected by the vehicle state detection unit 130. For example, when the vehicle state detection unit 130 detects that the vehicle is in an emergency state, the trigger signal generation unit 120 generates an emergency trigger signal. Here, in the ECU 100 shown in FIG. 1, the motor control unit 110 and the trigger signal generation unit 120 exist independently of each other. However, since the motor control unit 110 also has a function of the trigger signal generation unit 120, these are provided. May exist together.

  For example, when an SRS unit operation signal is input to the ECU 100 from an SRS unit (not shown), the vehicle state detection unit 130 detects that the vehicle is in an emergency state. For example, when the vehicle state detection unit 130 detects an emergency state of the vehicle, the trigger signal generation unit 120 generates an emergency trigger signal. In addition, the vehicle state detection unit 130 detects the state of the corresponding vehicle, for example, according to the operation of a VSA unit, an ACC unit, etc. (not shown), and the trigger signal generation unit 120 generates a corresponding trigger signal. Can do. Here, in the ECU 100 shown in FIG. 1, the trigger signal generation unit 120 and the vehicle state detection unit 130 exist independently, but the trigger signal generation unit 120 also has a function of the vehicle state detection unit 130. These may exist together.

  The energization amount adjustment unit 300 includes, for example, a driver IC (not shown), a current detection circuit 310 and a drive circuit 320 shown in FIG. 2, and adjusts the energization amount under the control of the motor control unit 110 of the ECU 100. Then, the power of the power source 200 is supplied to the drive motor 31. The energization amount adjustment unit 300 detects the drive current value of the drive motor 31 with the current detection circuit 310 and outputs it to the motor control unit 110 of the ECU 100, whereby the motor control unit 110 can execute current feedback control. Here, the energization amount adjustment unit 300 may be provided in the ECU 100, and at this time, the motor control unit 110 of the ECU 100 may have the function of the energization amount adjustment unit 300.

  FIG. 2 is a diagram showing the current detection circuit 310 and the drive circuit 320 in the configuration of the energization amount adjustment unit 300. The H bridge circuit as the drive circuit 320 in FIG. 2 is represented by a simple configuration in order to facilitate the description of the operation of the drive circuit 320. Therefore, the H bridge circuit may be provided with a freewheeling diode, a resistor, a capacitor, and the like as necessary. The H bridge circuit shown in FIG. 2 has four N-channel FETs (Field Effect Transistors) as switching elements as an example, but other types of transistors (for example, IGBTs) are provided instead. May be.

  Each gate of node A, node B, node C, and node D shown in FIG. 2 is connected to a corresponding terminal of a driver IC (not shown). Therefore, the driver IC can turn any switching element on or off under the control of the motor control unit 110 of the ECU 100. The node E is connected to the power source 200. Therefore, the driver IC can rotate the drive motor 31 forward, for example, when the switching element 321 and the switching element 324 are turned on. At this time, the driver IC is supplied to the drive motor 31 by, for example, always turning on the switching element 324 and turning on the switching element 321 only during the duty-on period of the duty ratio calculated by the motor control unit 110. Current value can be controlled. On the other hand, the driver IC can reversely rotate the drive motor 31, for example, when the switching element 322 and the switching element 323 are turned on. At this time, the driver IC is supplied to the drive motor 31 by, for example, always turning on the switching element 323 and turning on the switching element 322 only during the duty-on period of the duty ratio calculated by the motor control unit 110. Current value can be controlled.

  Also, the resistor 311 shown in FIG. 2 detects the current flowing through the drive motor 31, and its resistance value is set to a small value. The resistance value of the resistor 311 is, for example, 0.004 [Ω]. The resistor 311 is hereinafter also referred to as a shunt resistor 311. The current detection circuit 310 shown in FIG. 2 detects the supply current value supplied to the drive motor 31 by detecting the current value flowing through the resistor 311. Current detection circuit 310 outputs the detected current value to ECU 100 connected to node F.

  FIG. 3 shows an example in which the seat belt device 10 is provided so that a passenger sitting on a seat 19 provided in the vehicle can be appropriately restrained. Although the driver's seat side is shown in FIG. 3, the seat belt device 10 is also provided in the vehicle on the passenger seat side. The seat belt device 10 can wind up a webbing 16 that simultaneously restrains one shoulder and waist of an occupant by a retractor 14 provided on a side of the vehicle body.

  The seat belt device 10 has a three-point support structure in which the webbing 16 is supported by three anchors of an upper anchor 13, a center anchor 11, and a lower anchor 18. The upper anchor 13 is provided in the upper part of the side part of the vehicle body. The center anchor 11 is provided at a lower portion on the opposite side of the seat 19 from the upper anchor 13. The lower anchor 18 is provided in the lower part on the upper anchor 13 side with respect to the seat 19.

  The webbing 16 includes a shoulder belt 16b that restrains one shoulder of the occupant and a lap belt 16c that restrains the waist of the occupant. A tongue 23 is attached between the shoulder belt 16b and the lap belt 16c (the folded portion of the webbing 16). The tongue 23 is configured to be detachably attached to the buckle 24 fixed to the center anchor 11 with one touch.

  A buckle switch 27 is built in the buckle 24. The buckle switch 27 outputs an on signal when the tongue 23 is attached to the buckle 24, and does not output an on signal when the tongue 23 is not attached to the buckle 24. The buckle switch 27 is connected to the ECU 100 shown in FIG. 1, and the trigger signal generator 120, for example, when the buckle switch 27 is switched from the off state to the on state, and when the buckle switch 27 is switched from the on state to the off state. Generates a trigger signal when switching.

  4 is an exploded perspective view of the retractor 14 shown in FIG. In the example of FIG. 4, the retractor 14 includes a frame 41 attached to a side portion of the vehicle body. For example, a belt reel 15 is rotatably provided in the frame 41. A motor drive mechanism 35 is provided outside the frame 41. One end of the webbing 16 is attached to the belt reel 15, and one end side 16 a of the webbing 16 is drawn out of the frame 41 from the drawer opening 41 a of the frame 41.

  In the example of FIG. 4, the motor drive mechanism 35 has a gear housing 39 composed of, for example, an inner case 42 and an outer case 43, and the drive motor 31 is attached to the inner case 42 of the gear housing 39. The speed reduction / clutch mechanism 38 connected to the drive motor 31 is housed. The deceleration / clutch mechanism 38 is connected to the transmission mechanism 44 that connects the drive shaft 31a of the drive motor 31 to the belt reel 15, and is engaged with the transmission mechanism 44 to keep the drive motor 31 and the belt reel 15 in contact with each other. And a clutch mechanism 45 that releases the engagement to keep the drive motor 31 and the belt reel 15 in a disconnected state.

  In the example of the transmission mechanism 44 shown in FIG. 4, for example, a drive gear 47 is provided on the drive shaft 31 a, for example, a first intermediate gear 48 meshes with the drive gear 47, and a second intermediate gear 49, for example, engages with the first intermediate gear 48. For example, a third intermediate gear 51 is engaged with the second intermediate gear 49, and a fourth intermediate gear 52 is formed integrally with the third intermediate gear 51. The fourth intermediate gear 52 is disposed so as to mesh with the final gear 53, for example. Further, for example, a final gear 53 is rotatably attached to the outer case 43, for example, a reduction plate 54 is disposed coaxially with the final gear 53, and the reduction plate 54 is attached to, for example, a carrier 57 via pins 56, 56, 56 By being attached, one of the planetary gears 58, 58, 58 is rotatably supported by each of the pins 56, 56, 56. The carrier 57 is connected to the connecting shaft 15 a of the belt reel 15 while being engaged with, for example, the sun gear 62 of the final gear 53. Here, the bearings 63 and 64 support the carrier 57.

  In the example of FIG. 4, the clutch mechanism 45 includes a clutch member 65 (clutch pawl) rotatably attached to the inner case 42 via, for example, a pawl pin 68, a return spring 69 provided on the pawl pin 68, and a third intermediate A lever spring 72 attached to a support shaft 71 (see FIG. 5) of the gear 51, and a stopper member 74 (see FIG. 5) for positioning the clutch member 65 at a position that keeps the drive motor 31 and the belt reel 15 in a disconnected state. Prepare. Here, the clutch member 65 includes a locking claw 67, and the locking claw 67 is a claw that can be locked to a ratchet 61 b formed on the outer periphery of the internal gear 61. The distal end portion 72 a of the lever spring 72 is fitted in the fitting hole 66 of the clutch member 65.

  FIG. 5 is an explanatory diagram of the motor drive mechanism 35 shown in FIG. The motor drive mechanism 35 rotates the drive shaft 31a of the drive motor 31 in one direction (for example, counterclockwise direction) as indicated by an arrow A, thereby driving the drive gear 47 and the first to fourth intermediate gears 48, 49, 51. , 52 rotate as indicated by solid arrows, the final gear 53 rotates as indicated by arrow B, and the sun gear 62 rotates as indicated by arrow C.

  On the other hand, the motor drive mechanism 35 rotates the drive shaft 31a of the drive motor 31 to the other side (for example, clockwise direction) as indicated by a dotted arrow D, so that the drive gear 47 and the first to fourth intermediate gears 48, 49, 51, 52 rotate in the opposite direction to the solid arrow, the final gear 53 rotates as indicated by the dotted arrow E, and the sun gear 62 rotates as indicated by the dotted arrow F.

  FIG. 6 is an explanatory diagram of a contact state of the clutch mechanism 45 shown in FIG. In the example of FIG. 6, for example, as shown in FIG. 5, the third intermediate gear 51 rotates as indicated by an arrow G by rotating the drive motor 31 in one direction (for example, counterclockwise). At this time, the support shaft 71 rotates integrally with the third intermediate gear 51 as indicated by the arrow G, so that the lever spring 72 swings as indicated by the arrow H. The distal end portion 72a of the lever spring 72 urges the latching claw 67 of the clutch member 65 against the ratchet 61b against the spring force of the return spring 69. Thus, the swinging claw 67 is locked to the ratchet 61b.

  Thus, by rotating the drive motor 31 in one direction (for example, counterclockwise direction), the clutch member 65 can be moved to the contact position and can be locked to the transmission mechanism 44. When the locking claw 67 is locked to the ratchet 61b, the internal gear 61 is prevented from rotating in the clockwise direction, for example.

  By the way, when the fourth intermediate gear 52 rotates as indicated by the arrow G integrally with the third intermediate gear 51, the final gear 53 rotates as indicated by the arrow B. Accordingly, the sun gear 62 rotates integrally with the final gear 53 as indicated by an arrow C, and the planetary gears 58, 58, 58 rotate as indicated by solid arrows. Since the internal gear 61 is restrained from rotating in the clockwise direction, the planetary gears 58, 58, 58 revolve as indicated by the arrow J while rotating as indicated by the solid line arrows. As the planetary gears 58, 58, 58 revolve as indicated by an arrow J, the carrier 57 in FIG. 4 rotates, for example, in the counterclockwise direction. The belt reel 15 shown in FIG. 4 rotates together with the carrier 57 in a counterclockwise direction, for example, and the webbing 16 is wound around the belt reel 15.

  FIG. 7 is an explanatory diagram of the disengaged state of the clutch mechanism 45 shown in FIG. In the example of FIG. 7, for example, as shown in FIG. 5, the third intermediate gear 51 rotates as indicated by an arrow K by rotating the drive motor 31 in the other direction (for example, clockwise). At this time, the support shaft 71 rotates integrally with the third intermediate gear 51 as indicated by the arrow K, so that the lever spring 72 swings as indicated by the arrow L. Further, the clutch member 65 is moved away from the ratchet 61b by the pressing force applied to the clutch member 65 by the distal end portion 72a of the lever spring 72 and the spring force of the return spring 69. Since the clutch member 65 swings about the pawl pin 68 to the disengaged position as shown by the arrow M, the locking claw 67 is separated from the ratchet 61b.

  Thus, by rotating the drive motor 31 in the other direction (for example, clockwise), the clutch member 65 can be moved to the disengaged position. At this time, the clutch member 65 abuts against the stopper member 74 and is disengaged. Positioned. When the locking claw 67 of the clutch member 65 is separated from the ratchet 61b, the internal gear 61 becomes rotatable. In addition, the webbing 16 can be pulled out from the belt reel 15 by continuing the rotation of the drive motor 31 in the clockwise direction.

  Here, in the seat belt device 10, an open failure or a short failure related to electrical connection between the motor control unit 110 of the ECU 100 and the drive motor 31 may occur. Therefore, the seatbelt device 10 determines whether or not an open failure or a short failure has occurred regarding the electrical connection between the motor control unit 110 of the ECU 100 and the drive motor 31 when the drive motor 31 is not driven ( Hereinafter, it is also referred to as a constant diagnosis).

  An example of a method for determining whether or not a short fault has occurred in the regular diagnosis will be described with reference to FIG. For example, the motor control unit 110 of the ECU 100 applies a monitoring voltage to the energization amount adjustment unit 300. At this time, the motor control unit 110 monitors the value of the current flowing through the shunt resistor 311 with the H bridge circuit as the drive circuit 320 shown in FIG. For example, when it is determined that the current value flowing through the shunt resistor 311 detected by the current detection circuit 310 exceeds the threshold current value, the motor control unit 110 determines that a short circuit fault has occurred in the H bridge circuit. For example, when the monitoring voltage is 5 [V] and the resistance value of the entire H-bridge circuit is 10.2 [kΩ], the value of the current flowing through the shunt resistor 311 is about 0.5 [mA]. Therefore, the motor control unit 110 determines that a short circuit fault has occurred in the H bridge circuit when the current detection circuit 310 detects a current value exceeding 0.5 [mA], for example.

  An example of a method for determining whether or not an open failure has occurred in the continuous diagnosis will be described with reference to FIG. FIG. 8 shows a schematic equivalent circuit of the H-bridge circuit shown in FIG. In the configuration of the equivalent circuit of the H bridge circuit shown in FIG. 8, the parallel connection portion (between the node H and the node I) of the drive motor 31, the resistor 360, and the resistor 370 is directly connected to the resistor 350. Further, the equivalent circuit of the H bridge circuit is provided with a voltage detection circuit 380 (not shown in FIG. 2) that detects the voltage between the node H and the node I. Voltage detection circuit 380 outputs the detected voltage between node H and node I to ECU 100 connected to node J. The resistor 350, the resistor 360, and the resistor 370 are not shown in FIG. 2, but schematically represent resistance values in the H-bridge circuit as a load shown in FIG.

  For example, the motor control unit 110 of the ECU 100 applies a monitoring voltage between the node G and the ground GND in the equivalent circuit diagram of the H bridge circuit shown in FIG. At this time, the motor control unit 110 monitors the voltage value applied between the node H and the node I shown in FIG. For example, when it is determined that the voltage value between the node H and the node I detected by the voltage detection circuit 380 exceeds the threshold voltage, the motor control unit 110 determines that an open failure has occurred in the H bridge circuit.

  For example, when the resistance values of the resistor 350, the resistor 360, and the resistor 370 are 6.8 [kΩ], the combined resistance value between the node G and the node I is 10.2 [kΩ]. Here, for example, when the monitoring voltage applied between the node G and the ground GND is 5 [V] and no open failure has occurred in the H bridge circuit, the voltage between the node H and the node I is about 1.V. 7 [V]. On the other hand, for example, when an open failure has occurred in the connector of the drive motor 31, no current flows through the resistor 360, so the voltage between the node H and the node I is 2.5 [V]. Therefore, the motor control unit 110 determines that an open failure has occurred in the H-bridge circuit when the voltage detection circuit 380 detects a voltage exceeding, for example, 1.7 [V]. In the calculation example described above, it is assumed that the resistance value of the drive motor 31 is included in the resistance value of the resistor 360.

  The seat belt device 10 stops the control of the seat belt device 10 when it is determined that an open failure or a short failure related to the electrical connection between the motor control unit 110 of the ECU 100 and the drive motor 31 has occurred in the continuous diagnosis. To do. In the above-described constant diagnosis, the detection current value and the detection voltage value have been described as being input to the motor control unit 110. However, for example, the ECU 100 may further include an abnormality detection unit that is not illustrated, and the abnormality detection unit may include A detection voltage value may be input.

2. Operation of Seat Belt Device An example of the operation of the seat belt device 10 will be described with reference to the flowchart shown in FIG. In step S01, the motor control unit 110 of the ECU 100 determines whether or not an emergency trigger signal is generated by the trigger signal generation unit 120. When the motor control unit 110 determines that an emergency trigger signal has been generated, the flow proceeds to step S02. On the other hand, when the motor control unit 110 determines that the emergency trigger signal is not generated, the flow proceeds to step S10.

  In step S02, the motor control unit 110 of the ECU 100 sets a target current value, and executes current feedback control so that the drive current value supplied to the drive motor 31 matches the target current value. Here, the set target current value is a current value that can rapidly wind the webbing 16 and restrain the occupant with strong tension. The target current value is 20 [A], for example.

  In step S03, the motor control unit 110 of the ECU 100 determines whether the duty ratio calculated so that the drive current value matches the target current value is equal to or greater than the first duty ratio. At the same time, the motor control unit 110 determines whether the drive current value of the drive motor 31 detected by the current detection circuit 310 of the energization amount adjustment unit 300 is smaller than the first current value. When the motor control unit determines that the calculated duty ratio is greater than or equal to the first duty ratio and the detected drive current value is smaller than the first current value, the flow proceeds to step S04. On the other hand, when the motor control unit does not determine that the calculated duty ratio is equal to or greater than the first duty ratio and the detected drive current value is smaller than the first current value, the flow proceeds to step S06. . Here, the first duty ratio is, for example, 90 [%], and the first current value is, for example, 4 [A].

  That is, step S03 is to determine whether or not a state in which the drive current value of the drive motor 31 does not increase when the motor control unit 110 of the ECU 100 increases the duty ratio. The state in which the drive current value of the drive motor 31 does not increase when the duty ratio is increased is highly likely that an open failure has occurred. Therefore, step S03 is a step of determining whether or not an open failure has occurred between the motor control unit 110 and the drive motor 31.

  In step S04, the motor control unit 110 of the ECU 100 executes fixed duty control with a fixed duty ratio instead of the current feedback control being executed. Here, the fixed duty ratio is, for example, 40 [%]. That is, when it is determined in step S03 that an open failure has occurred, motor control unit 110 executes fixed duty control instead of current feedback control. Therefore, the seat belt device 10 can avoid a sudden change in the drive current of the drive motor 31 when an open failure is resolved during winding of the webbing 16. Moreover, since the seatbelt apparatus 10 can continue winding of the webbing 16 when an open failure occurs during winding of the webbing 16, it can restrain a passenger | crew appropriately.

  In step S05, the motor control unit 110 of the ECU 100 determines whether or not a predetermined time has elapsed since the time when the fixed duty control was executed in step S04. When the motor control unit 110 determines that a predetermined time has elapsed since the time when the fixed duty control was executed in step S04, the flow proceeds to step S08. On the other hand, when the motor control unit 110 determines that the predetermined time has not elapsed since the time when the fixed duty control was executed in step S04, the flow repeats the determination in step S05. Here, the predetermined time is, for example, 1000 [ms].

  As a result of the determination in step S03, when the flow proceeds to step S06, the motor control unit 110 of the ECU 100 has a duty ratio calculated so that the drive current value matches the target current value is equal to or less than the second duty ratio. It is determined whether or not. At the same time, the motor control unit 110 determines whether or not the drive current value of the drive motor 31 detected by the current detection circuit 310 of the energization amount adjustment unit 300 is greater than the second current value. When the motor control unit determines that the calculated duty ratio is less than or equal to the second duty ratio and the detected drive current value is greater than the second current value, the flow proceeds to step S08. On the other hand, when the motor control unit does not determine that the calculated duty ratio is less than or equal to the second duty ratio and the detected drive current value is greater than the second current value, the flow proceeds to step S07. . Here, the second duty ratio is, for example, 10 [%], and the second current value is, for example, 10 [A].

  That is, in step S06, the motor control unit 110 of the ECU 100 determines whether or not a state where the drive current value of the drive motor 31 is large occurs when the duty ratio is small. When the duty ratio is small, the state in which the drive current value of the drive motor 31 is large is highly likely that a short circuit failure has occurred. Therefore, step S06 is a step of determining whether or not a short circuit failure has occurred between the motor control unit 110 and the drive motor 31. As a result of the determination in step S06, when the process proceeds to step S08 (when a short failure occurs), the drive of the drive motor 31 is stopped in step S09 described later. Therefore, the seat belt device 10 can avoid a large current from flowing in the seat belt device 10 when a short circuit failure occurs during the winding of the webbing.

  As a result of the determination in step S06, when the flow proceeds to step S07, the motor control unit 110 of the ECU 100 determines whether or not a predetermined time has elapsed since the time when the current feedback control was executed in step S02. When the motor control unit 110 determines that a predetermined time has elapsed since the time when the current feedback control was executed in step S02, the flow proceeds to step S08. On the other hand, when the motor control unit 110 determines that the predetermined time has not elapsed since the time when the current feedback control was executed in step S02, the flow repeats the determination in step S07. Here, the predetermined time is, for example, 1000 [ms]. The predetermined time in step S07 and the predetermined time in step S05 may be the same or different.

  In step S08, the motor control unit 110 of the ECU 100 controls the energization amount adjustment unit 300 to rotate (reverse operation) the drive motor 31 in the direction in which the webbing 16 is pulled out, and the flow proceeds to step S09. Here, the motor control unit 110 rotates the drive motor 31 in the direction in which the webbing 16 is pulled out because the drive motor 31 is rotated in the direction in which the webbing 16 is wound up in FIG. This is because the clutch mechanism 45 shown (the state of the clutch mechanism 45 shown in FIG. 6) is again disengaged (the state of the clutch mechanism 45 shown in FIG. 7). Therefore, in step S08, the motor control unit 110 may rotate the drive motor 31 in the direction in which the webbing 16 is pulled out for a very short time (for example, 200 [ms]).

  In step S09, the motor control unit 110 of the ECU 100 stops driving the drive motor 31, and the flow returns to START.

  As a result of the determination in step S01, when the flow proceeds to step S10, the seatbelt device 10 executes the above-described constant diagnosis. That is, the seatbelt device 10 determines whether or not an open failure or a short-circuit failure related to electrical connection between the motor control unit 110 of the ECU 100 and the drive motor 31 has occurred. In contrast to the normal diagnosis, the determinations in step S03 and step S04 are also called driving diagnosis.

  In step S10, the motor control unit 110 of the ECU 100 applies a monitoring voltage to the energization amount adjustment unit 300, and determines whether or not the value of the current flowing through the shunt resistor 311 detected by the current detection circuit 310 is greater than the threshold current. When the motor control unit 110 determines that the value of the current flowing through the shunt resistor 311 is greater than the threshold current, it determines that a short circuit failure has occurred and stops the control of the seat belt device 10. On the other hand, when the motor control unit 110 determines that the value of the current flowing through the shunt resistor 311 is not greater than the threshold current, the flow proceeds to step S11. Here, the threshold current is, for example, 0.5 [mA].

  In step S11, the motor control unit 110 of the ECU 100 applies a monitoring voltage to the energization amount adjustment unit 300, and the voltage between the node H and the node I in the equivalent circuit of the H bridge circuit shown in FIG. 8 detected by the voltage detection circuit. Is greater than the threshold voltage. When the motor control unit 110 determines that the voltage between the node H and the node I in the equivalent circuit of the H bridge circuit illustrated in FIG. 8 is greater than the threshold voltage, it determines that an open failure has occurred, and the seat belt device 10 Stop the control. On the other hand, when the motor control unit 110 determines that the voltage between the node H and the node I in the equivalent circuit of the H bridge circuit shown in FIG. 8 is not larger than the threshold voltage, the flow returns to START. Here, the threshold voltage is, for example, 1.7 [V].

  As a result of the constant diagnosis, when it is determined that an open failure or a short failure related to the electrical connection between the motor control unit 110 of the ECU 100 and the drive motor 31 has occurred, the control of the seat belt device 10 is stopped. Here, when the control of the seat belt device 10 is stopped, the motor control unit 110 may notify the occupant using an indicator or the like provided in the vehicle.

  The specific examples of the numerical values such as the current value and the predetermined time used in the description of the flowchart shown in FIG. 9 do not limit the contents of the present invention, but are only specific examples. The numerical values described above may be set in advance when the seat belt device 10 is manufactured, or may be changed by a passenger according to preference.

  The present invention is not limited to the above-described exemplary embodiments, and those skilled in the art will be able to easily modify the above-described exemplary embodiments to the extent included in the claims. .

  DESCRIPTION OF SYMBOLS 10 ... Seat belt apparatus, 14 ... Retractor, 15 ... Belt reel, 16 ... Webbing, 31 ... Drive motor, 35 ... Motor drive mechanism, 100 ... ECU, 110. ..Motor control unit, 120... Trigger signal generation unit, 130... Vehicle state detection unit, 200.

Claims (5)

A belt reel that winds up the webbing;
A drive motor for rotating the belt reel;
A vehicle state detector for detecting the state of the vehicle;
A trigger signal generator for generating a trigger signal for starting control of the drive motor in accordance with the state of the vehicle;
A motor control unit for controlling the drive motor in response to the trigger signal;
Have
The motor control unit is configured to control the motor control based on a drive current value of the drive motor when the duty ratio calculated by the motor control unit during execution of the control of the drive motor is equal to or greater than a first duty ratio. Determine whether an open failure has occurred with respect to the connection between the motor and the drive motor,
When the motor control unit determines that the open failure has occurred, it executes fixed duty control instead of current feedback control ,
The seat belt device , wherein the fixed duty ratio in the fixed duty control is set to a duty ratio smaller than the first duty ratio .   The seat belt device according to claim 1, wherein the motor control unit stops driving of the drive motor after a predetermined time has elapsed from a certain time when the fixed duty control is executed. The motor control unit determines whether a short-circuit failure has occurred in the connection between the motor control unit and the drive motor based on the drive current value of the drive motor during the control of the drive motor. Judgment further,
The seat belt device according to claim 1 or 2, wherein when the motor control unit determines that the short-circuit failure has occurred, the motor control unit stops driving the drive motor. The motor control unit is configured such that the duty ratio calculated by the motor control unit during execution of control of the drive motor is equal to or greater than the first duty ratio, and the detected drive current value is a first current. 2. The seat belt device according to claim 1, wherein when the value is smaller than the value, it is determined that the open failure related to the connection between the motor control unit and the drive motor has occurred. The motor control unit has a duty ratio calculated by the motor control unit during the control of the drive motor equal to or lower than a second duty ratio which is a duty ratio smaller than the first duty ratio; and When the detected drive current value is greater than a second current value that is a drive current value greater than the first current value, it is determined that a short circuit failure has occurred with respect to the connection between the motor control unit and the drive motor. The seat belt device according to claim 4.

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