JP2005271769A - Seat belt device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a seat belt device capable of detecting failure of a motor for winding a seat belt. <P>SOLUTION: This seat belt device 1 is provided with a seat belt winding device 3 having a reel 31 to which the seat belt is wound, the motor 30 capable of being driven to both of normal and reverse directions and winding up the seat belt by rotating the reel 31 by driving to the normal direction; and a seat belt control device 2 having a motor drive circuit 23 for driving the motor 30, electric current detection devices 24 and 25 for detecting an electric current value supplied to the motor 30, and a CPU 22 determining necessity of winding of the seat belt and transmitting a driving instruction to the normal direction to the motor drive circuit 23 when it is determined that winding of the seat belt is necessary. The CUP 22 has a motor diagnosis function for driving the motor 30 to the reverse direction and diagnosing a state of the motor 30 from the electric current value detected by the electric current detection devices 24 and 25 at that time. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a seat belt device that restrains an occupant to a seat to make the occupant safe.

As a passenger protection device, for example, a pretensioner mechanism that detects a vehicle collision in advance based on information such as an inter-vehicle distance from a preceding vehicle or a brake operation state by a driver, and winds up a seat belt as necessary. An attached seat belt device has been developed (see, for example, Patent Document 1). In this type of seat belt device, a motor is incorporated in the seat belt retractor, and when it is determined that a collision is inevitable, the motor is driven and the seat belt is retracted.
JP-A-6-286581

  Since the pretensioner mechanism operates in an emergency, the motor is not normally driven. For this reason, for example, if water adheres around the rotor of the motor and rust is generated, the motor may be fixed. If the motor is fixed, the pretensioner mechanism cannot be operated when necessary.

  In order to recognize such a malfunction of the motor in advance, for example, the motor may be actually driven to perform a seat belt winding test. However, when the seat belt is worn and the motor is driven to wind up the seat belt, the restraint force by the seat belt increases, and the passenger feels uncomfortable.

  The present invention has been made in view of such a situation, and an object of the present invention is to provide a seat belt device that can detect a malfunction of a seat belt winding motor.

  (1) The seat belt device of the present invention includes a reel on which the seat belt is wound, a motor that can be driven in both forward and reverse directions, and that rotates the reel by driving in the forward direction to wind the seat belt. , A motor drive circuit that drives the motor, a current detection device that detects a current value flowing through the motor, and the necessity of winding the seat belt In the case of determination, a seatbelt device comprising: a CPU that issues a forward drive instruction to the motor drive circuit; and a seatbelt control device, wherein the CPU drives the motor in the reverse direction. In this case, the motor has a motor diagnosis function for diagnosing the state of the motor from the current value detected by the current detection device.

  The motor is driven in both forward and reverse directions by energization from the motor drive circuit. When the motor is driven in the forward direction, the reel rotates and the seat belt is wound up. On the other hand, when the motor is driven in the reverse direction, the driving force of the motor is not transmitted to the reel, and the motor runs idle. Therefore, the seat belt is not pulled out.

  The CPU drives the motor in the reverse direction and diagnoses the state of the motor from the current value flowing through the idling motor. When the motor is driven by applying a constant voltage, the value of the current flowing through the motor differs depending on whether the motor is normal or if a problem such as sticking occurs in the motor. Thus, for example, a threshold value for determining a malfunction of the motor is set in advance, and when the detected current value exceeds the threshold value, it is determined that a malfunction has occurred in the motor. it can.

  Thus, according to the seat belt device of the present invention, it is possible to detect a malfunction of the motor in advance. The motor can be maintained in a normal state by performing an appropriate treatment based on the diagnosis result. As a result, the pretensioner mechanism can be reliably operated in an emergency. In the seat belt device of the present invention, the motor is idled to diagnose the state of the motor. Since the state of the motor is diagnosed without the seat belt being retracted or pulled out, the passenger is not discomforted.

  According to the seat belt device of the present invention, it is possible to detect a malfunction of the motor in advance. For this reason, the operation reliability of the seat belt device is high. In the seat belt device of the present invention, the motor is driven in the reverse direction, and the state of the motor is diagnosed in the idle state. Therefore, the seat belt is not taken up and pulled out, and the passenger is not discomforted.

  Hereinafter, embodiments of the seat belt device of the present invention will be described. First, the configuration of the seat belt device of the present embodiment will be described. FIG. 1 shows a block diagram of the seat belt device of the present embodiment. As shown in FIG. 1, the seat belt device 1 includes a seat belt control device 2 and a seat belt winding device 3.

  The seat belt control device 2 includes a power supply circuit 20, a communication I / F (interface) 21, a CPU (central processing unit) 22, a motor drive circuit 23, a current detection resistor 24, a current detection circuit 25, A diagnostic I / F 26.

  Power supply circuit 20 is connected to vehicle battery 7 through power supply line L1. An ignition switch 70 is disposed on the power supply line L1. The power supply circuit 20 is a transformer that converts the 12V voltage of the vehicle battery 7 into a 5V voltage. The power supply circuit 20 is connected to the CPU 22 by a power supply line L2.

  The communication I / F 21 is connected to the millimeter wave radar 50 and the master cylinder pressure sensor 51 through a signal line S4. The millimeter wave radar 50 detects the distance, relative speed, and the like of the vehicle ahead and an obstacle by emitting the millimeter wave forward. The master cylinder pressure sensor 51 detects a driver's brake depression force.

  The CPU 22 is connected to the communication I / F 21 through the signal line S5. The CPU 22 determines whether or not a collision is inevitable based on data transmitted from the millimeter wave radar 50 and the master cylinder pressure sensor 51. In addition, the CPU 22 diagnoses the motor 30 described later.

  The motor drive circuit 23 is connected to the vehicle battery 7 by the power line L3. The signal line S1 is connected to the CPU 22. The motor drive circuit 23 drives the motor 30 in both forward and reverse directions according to the drive signal transmitted from the CPU 22. The current detection resistor 24 is a resistor for checking the energization state of the motor 30. The current detection circuit 25 is a circuit for detecting the current value of the current detection resistor 24. The current detection circuit 25 transmits the detected current value to the CPU 22 via the signal line S3. Here, the current detection resistor 24 and the current detection circuit 25 are included in the current detection device constituting the present invention.

  The diagnostic I / F 26 is connected to the CPU 22 through a signal line S6 and to the indicator 6 through a signal line S7. When a motor failure warning instruction is transmitted from the CPU 22, the indicator 6 is lit.

  FIG. 2 shows a seat belt winding mechanism in the seat belt winding device. FIG. 3 shows a cross-sectional view of the clutch in FIG. As shown in FIGS. 1 to 3, the seat belt retractor 3 includes a motor 30, a reel 31, and a clutch 33.

  The clutch 33 includes a clutch inner 330, a clutch outer 331, and an engaging claw 332. The clutch inner 330 has a cylindrical shape. The clutch inner 330 is mounted around the outer periphery of one end of the rotating shaft 300 of the motor 30. Convex portions 334 are formed on the outer peripheral surface of the clutch inner 330 every 60 °. Grooves 335 are formed on the inner peripheral surface 333 of the clutch outer 331 every 60 °. The groove portion 335 has a locking surface 336 that locks the engaging claw 332. The engaging claw 332 is pivoted to the base of the convex portion 334 of the clutch inner 330. A return spring is attached to the pivot shaft of the engaging claw 332. The engaging claw 332 is urged toward the inner peripheral surface of the clutch outer 331 by the urging force of the return spring.

  A seat belt 32 is wound around the reel 31. A pulley portion 310 is formed at one end of the reel 31. The pulley unit 310 of the reel 31 and the clutch 33 are connected by a belt 34.

  When the motor 30 is driven in the forward direction (clockwise) by the motor drive circuit 23, the clutch inner 330 is rotated in the same direction by the rotation of the rotating shaft 300. At this time, the claw end portion 337 of the engagement claw 332 and the locking surface 336 of the clutch outer 331 come into contact with each other. When the claw end portion 337 of the engagement claw 332 presses the locking surface 336, the clutch outer 331 also rotates in the same direction. That is, the driving force is transmitted from the clutch inner 330 to the clutch outer 331. This driving force is transmitted to the pulley section 310 of the reel 31 via the belt 34. As the pulley unit 310 rotates, the reel 31 also rotates in the forward direction. Thereby, the seat belt 32 is wound up.

  On the other hand, when the motor 30 is driven in the reverse direction (counterclockwise), the rotation of the rotary shaft 300 causes the clutch inner 330 to rotate in the same direction. At this time, the engaging claw 332 contacts the inner peripheral surface 333 of the clutch outer 331 and is pressed against the outer peripheral surface side of the clutch inner 330 while being elastically deformed. Since the engaging claw 332 is accommodated between the two convex portions 334, the clutch outer 331 is not pressed by the engaging claw 332. Therefore, only the clutch inner 330 rotates and the clutch outer 331 does not move. That is, the driving force is not transmitted from the clutch inner 330 to the clutch outer 331. For this reason, the reel 31 does not rotate, and the motor 30 idles.

  Next, the operation of the seat belt device of this embodiment will be described. When the ignition switch 70 is turned on, a 12V voltage is applied from the vehicle battery 7 to the power supply circuit 20 via the power supply line L1. The 12V voltage is transformed to 5V in the power supply circuit 20. The transformed 5V voltage is supplied to the CPU 22 via the power line L2. On the other hand, the 12V voltage of the vehicle battery 7 is also applied to the motor drive circuit 23 via the power supply line L3. Thereby, the diagnosis of the motor 30 is started.

  First, a reverse drive signal is transmitted from the CPU 22 to the motor drive circuit 23 via the signal line S1. FIG. 4 shows a circuit diagram of the motor drive circuit. As shown in FIG. 4, the motor drive circuit 23 includes four FETs (field effect transistors) 230a to 230d. These four FETs 230a to 230d form an H bridge circuit. The current detection resistor 24 is connected in series with the motor drive circuit 23. The FETs 230c and 230d are turned on for a predetermined time by the drive signal from the CPU 22. Therefore, a current flows through the motor 30 as indicated by a dotted arrow B in FIG. Thus, the motor 30 is driven in the reverse direction. At this time, as shown in FIG. 2, the motor 30 idles and the seat belt 32 is not pulled out. The current flowing through the motor 30 is detected by the current detection circuit 25 via the signal line S2. The detected current value is transmitted to the CPU 22 via the signal line S3.

  The CPU 22 compares the detected current value with a threshold value stored in advance, and determines whether the motor 30 is good or bad. For example, if the detected current value exceeds a threshold value, the possibility of motor 30 being stuck is high, so a failure determination is made. In this case, a motor failure warning instruction signal is transmitted from the CPU 22 to the indicator 6 via the signal line S6, the diagnostic I / F 26, and the signal line S7, and the indicator 6 is turned on.

  After a predetermined time has elapsed from the end of the motor diagnosis, the seat belt device 1 is switched to the normal mode. For example, information such as the distance and relative speed between the millimeter wave radar 50 and the preceding vehicle, and brake pedal force information from the master cylinder pressure sensor 51 are transmitted via the signal line S4, the communication I / F 21, and the signal line S5. When the information is transmitted to the CPU, the CPU 22 determines whether or not the vehicle is inevitable to collide with the transmitted information. In the case of collision unavoidable determination, a forward drive signal is transmitted to the motor drive circuit 23 via the signal line S1. The FETs 230a and 230b are turned on by a drive signal from the CPU 22. For this reason, as indicated by the dotted arrow A in FIG. Thus, the motor 30 is driven in the positive direction. At this time, as shown in FIG. 2, the reel 31 rotates in the forward direction, and the seat belt 32 is wound by a predetermined amount.

  Next, the effect of the seat belt device of the present embodiment will be described. In the seat belt device 1 of the present embodiment, the state of the motor 30 is diagnosed in a state in which the motor 30 is rotated in the reverse direction and idled. When the motor 30 is diagnosed, the seat belt 32 is not taken up and pulled out, so that the state of the motor 30 can be diagnosed without giving a sense of incongruity to the passenger. In addition, by using the clutch 33 in the seat belt 32 winding mechanism, the motor 30 can be idled with a simple configuration, which is practical. Thus, according to the seatbelt apparatus 1 of this embodiment, since malfunctions, such as adhesion of the motor 30, can be detected in advance, the operational stability of the pretensioner mechanism is improved.

  The embodiment of the seat belt device of the present invention has been described above. However, the seat belt device of the present invention is not limited to the above embodiment. The seat belt device of the present invention can be implemented in various forms with modifications and improvements that can be made by those skilled in the art without departing from the gist of the present invention.

  For example, in the above-described embodiment, a clutch is used for the seat belt winding mechanism, and the motor is idled during reverse driving. However, the configuration of the seat belt winding mechanism is not limited to the above embodiment. The seat belt winding mechanism may be any mechanism that does not transmit the driving force to the reel when the motor is driven in the reverse direction.

  Moreover, in the said embodiment, the millimeter wave radar and the master cylinder pressure sensor were used as a collision prediction apparatus which detects a collision in advance. However, the type of collision prediction device is not particularly limited. For example, an ultrasonic radar or the like may be used for detecting a preceding vehicle or the like, and an ABS (anti-lock brake system) operation signal detection sensor, a vehicle speed sensor, or the like may be used for detecting a sudden braking. Moreover, you may comprise a collision prediction apparatus only from any one of detection of a preceding vehicle etc., and sudden braking detection.

It is a block diagram which shows one Embodiment of the seatbelt apparatus of this invention. It is the schematic of the seatbelt winding mechanism in the seatbelt apparatus. FIG. 3 is a cross-sectional view taken along the axis of the clutch in FIG. 2. It is a circuit diagram of a motor drive circuit.

Explanation of symbols

1: Seat belt device 2: Seat belt control device 20: Power supply circuit 21: Communication I / F 22: CPU 23: Motor drive circuit 230a to 230d: FET 24: Current detection resistor 25: Current detection circuit 26: I for diagnosis / F
3: Seat belt retractor 30: Motor 300: Rotating shaft 31: Reel 310: Pulley portion 32: Seat belt 33: Clutch 330: Clutch inner 331: Clutch outer 332: Engaging claw 333: Inner peripheral surface 334: Convex portion 335: Groove 336: Locking surface 337: Claw end 34: Belt 50: Millimeter wave radar 51: Master cylinder pressure sensor 6: Indicator 7: Vehicle battery 70: Ignition switch

Claims (1)

A reel around which a seat belt is wound;
A seat belt retractor having a motor that can be driven in both forward and reverse directions and that rotates the reel by forward drive to wind the seat belt;
A motor drive circuit for driving the motor;
A current detection device for detecting a current value flowing through the motor;
A seatbelt control device having a CPU for determining the necessity of winding the seatbelt, and in the case of the determination of the need for winding, a CPU for issuing a forward drive instruction to the motor drive circuit;
A seat belt device comprising:
The CPU has a motor diagnosis function for driving the motor in the reverse direction and diagnosing the state of the motor from the current value detected by the current detection device at that time.

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