JP4246170B2 - Crew restraint system - Google Patents

Description

  The present invention relates to an occupant restraint device that predicts the risk of colliding with a front obstacle and winds up a seat belt in accordance with the collision risk obtained by this prediction.

  Many proposals have been made for occupant restraint devices, and the seat belt device disclosed in Patent Document 1 below is one example. In the technology, a seat belt, a first pretensioner mechanism that restrains an occupant within a range in which a vehicle collision avoidance operation is possible, a second pretensioner mechanism that restrains the occupant against a vehicle collision, First command means for predicting a collision and outputting an operation signal to the first pretensioner mechanism, and second command means for determining a vehicle collision and outputting an operation signal to the second pretensioner mechanism are provided. ing. According to this prior art, the first tension can be generated by the first pretensioner mechanism by predicting the collision. After the collision, the second tension is generated by the second pretension mechanism, and the occupant Can be restrained accurately. As a recent technique corresponding to this patent, a technique has been proposed in which the first pretensioner mechanism is a motor and the second pretensioner mechanism is an explosive pretensioner.

  Furthermore, a technique has been proposed in which the pretensioner mechanism using the first motor is utilized for the purpose of bodily sensation warning and occupant restraint. Specifically, when the risk of collision of the host vehicle is slight, the seat belt is wound with a first tension that does not affect the braking operation of the driver. Thus, it is possible to notify the driver that there is a danger of a collision as a bodily sensation alarm as well as an alarm sound and a warning light (first alarm). When the risk of collision is severe, the seat belt is wound with the second tension, which is stronger than the first tension, and the occupant is restrained to the seat back immediately before the collision (second alarm). Thus, the frequency of using a motor that winds up a seat belt is increasing.

Japanese Patent No. 2946995

  By the way, when a vehicle equipped with the above function is used in an actual environment, there are various situations where the seat belt needs to be wound up by the first alarm or the second alarm. This is due to various factors such as the driving environment and driving conditions, as well as the driving skill of the driver. However, the amount of heat generated tends to increase when the motor is used frequently.

  Usually, a motor used for winding a seat belt often has an overheat protection function generally called a thermal protector as a temperature countermeasure. A thermal protector is a device for preventing burnout that occurs when the coil temperature of a motor exceeds a predetermined heat-resistant temperature. Once the coil temperature exceeds the operating temperature, the built-in contact is turned off to cut off the current supply until the temperature falls below the return temperature (the motor cannot be driven while the current supply is cut off). .

There are the following two problems in using the motor equipped with the above-described thermal protector for warning and restraining purposes for passengers.
First, there is a problem that the thermal protector is activated during occupant restraint (second alarm) due to overheating of the motor due to frequent use of the sensory alarm (first alarm).
Second, there is a problem that the thermal protector operates before occupant restraint (second alarm) due to overheating of the motor due to frequent use of the sensation alarm (first alarm).
In either case, the result is that the purpose of protecting passengers and reducing injury cannot be achieved.

  The present invention has been made to solve the above problem. From the viewpoint of passenger protection, when the motor is in an overheated state, the overheat protection is provided even if it is sacrificed by stopping the sensory alarm (first alarm). It is an object of the present invention to provide an occupant restraint device that can avoid the operation of the function (thermal protector) and can reliably restrain the occupant when the occupant is restrained (second alarm).

According to the present invention, a warning means for outputting a first warning signal and a second warning signal indicating that the danger level is higher than the first warning signal based on a collision risk with an obstacle ahead of the vehicle, and a predetermined temperature exceeded A motor that winds up a seat belt having an overheat protection means that cuts off the supply of power, and a first motor torque and a second motor torque that is larger than the first motor torque in response to the first and second alarm signals, respectively. A seat belt motor control means for calculating a control amount for winding the seat belt and outputting a control signal indicating the control amount, and a motor drive for generating a voltage required for driving the motor based on the control signal output from the seat belt motor control means Means, a motor temperature acquisition means for detecting a motor temperature or estimating a corresponding temperature, and a preset threshold value based on the operating temperature of the overheat protection means. Motor overheat determining means for determining that the motor is in an overheated state when the motor temperature of the means exceeds, and when the seat belt motor control means outputs the first alarm signal, the seat belt motor control means When the motor overheat determining means determines that the motor is in an overheated state, the output of the control signal for winding the seat belt with the first motor torque is temporarily stopped, and the alarm means An occupant restraint device that winds up the seat belt with the second motor torque even when the motor overheat determination means determines that the motor is overheated when outputting an alarm signal. It is in.

  In the present invention, from the viewpoint of occupant protection, when the motor is in an overheated state, the sensory alarm (first alarm) is stopped and the operation of the overheat protection function (thermal protector) is avoided even if this is sacrificed. The passenger can be surely restrained when the passenger is restrained (second alarm).

Embodiment 1 FIG.
FIG. 1 is a block diagram showing a configuration of an occupant restraint device according to an embodiment of the present invention. The obstacle detection means 1 detects an obstacle existing in front of the vehicle. The collision risk calculation means 2 calculates the collision risk between the obstacle and the host vehicle. The warning means 3 outputs first and second warning signals based on the collision risk. The seat belt motor control means 4 calculates a control amount to take up the seat belt with the first and second motor torques according to the alarm signal, and outputs the control signal. The motor driving means 5 generates a voltage required for driving the motor. The motor current detection means 6 detects the motor current. The motor 7 is a motor for winding up a seat belt having an overheat protection means 8 that cuts off the supply of power when a predetermined temperature is exceeded. The motor temperature detection means 9 (motor temperature acquisition means) detects the motor temperature or estimates the corresponding temperature. The motor overheat determination means 10 determines that the motor is overheated and outputs a determination result when the motor temperature exceeds a preset threshold value based on the operating temperature of the overheat protection means 8.

  The obstacle detection means 1 is a non-contact sensor such as a millimeter wave radar or a laser radar. The millimeter wave radar is mounted in the center of the front of the host vehicle, transmits radio waves toward the front of the vehicle, determines the distance from the obstacle until the reflected wave returns, and changes the frequency of the reflected wave due to the Doppler effect. The relative speed with the obstacle can be obtained. The detection result is provided to the subsequent collision risk calculation means 2 using communication means such as serial communication or CAN (Controller Area Network) communication. The collision risk calculation means 2 calculates the risk of collision of the host vehicle with an obstacle based on the information acquired from the millimeter wave radar and the braking information (for example, vehicle speed and yaw rate signal) of the host vehicle. The vehicle speed and yaw rate signal are obtained from an electronic control device (not shown) for vehicle driving braking. The warning means 3 outputs different levels of warning signals based on the collision risk.

  Here, a process from detection of a vehicle in front (obstacle) to output of an alarm signal will be described with reference to FIG. First, FIG. 2 (a) shows the relative distance relationship with the preceding vehicle. The vertical axis represents relative distance, and the horizontal axis represents time. Therefore, the figure shows how the inter-vehicle distance decreases with time. Next, (b) of FIG. 2 shows the collision risk on the vertical axis. The collision risk increases as the inter-vehicle distance decreases after the millimeter wave radar detects the preceding vehicle at a certain time T1. Is shown. When the collision risk exceeds the first alarm determination value J1, the first alarm signal 21 is output as shown in FIG. The vertical axis of the figure indicates the motor current value, and the area of the first alarm signal 21 means the amount of heat generated when the motor current C1 is energized during the motor driving time T2. Usually, since the driver performs the braking operation of the vehicle in response to the first warning signal 21, the inter-vehicle distance is widened and the collision risk is reduced. However, if the braking operation is not performed for some reason or the preceding vehicle is suddenly If the speed is reduced, the risk of collision further increases. When the collision risk exceeds the second alarm determination value J2, the second alarm signal 22 is output. Similar to the above, the second alarm signal 22 indicates that the motor current C2 is energized during the motor driving time T3. From the above, it can be seen that the first alarm signal 21 is output when a minor collision risk is detected, and the second alarm signal 22 is output when a severe collision risk is detected. The collision risk degree calculation means 2 and the warning means 3 can be realized by the same or separate electronic control units (ECUs).

  In FIG. 1, the seat belt motor control means 4, the motor drive means 5, the motor current detection means 6, and the motor 7 constitute one current feedback loop. FIG. 3 is a block diagram showing an outline of feedback control. In the following description, current feedback control will be described as an example of seat belt motor control. However, in carrying out the present invention, other control objects (for example, torque and position) and other control methods (for example, feed) It may be realized by forward control).

  First, the seat belt motor control means 4 is a microcomputer having a PID controller 31 in PID (Proportional Integral Differential) control which is a typical technique of control technology. In the microcomputer, a target current value 32 required for driving the motor 7 is set in advance, and comparison calculation is performed with the motor current value 33 detected via the motor current detecting means 6. As a result of comparison, when the motor current value 33 is lower than the target current value 32, the motor drive voltage (motor voltage) 34 is increased, and when the motor current value 33 is higher, the motor drive voltage 34 is increased. It is necessary to manipulate the applied voltage so as to lower the value. Generally, switching control with high power efficiency is used as a voltage control method for a motor. A PWM (Pulse Width Modulation Control) control method is widely used in switching control. Based on the result of the comparison determination, a PWM duty ratio for obtaining an appropriate motor drive voltage 34 is calculated by the duty conversion means 35, and a PWM pulse 36 is output to the motor drive means 5.

  The motor driving means 5 is a switching circuit composed of electronic components. The circuit uses an H-bridge circuit composed of four FETs (field effect transistors). When the motor drive voltage 34 generated by the switching circuit is applied to the motor 7, the motor 7 winds up the seat belt SB with a desired motor torque (the first and second motor torques). The motor current detection means 6 is an electronic circuit that constitutes a differential amplifier. The potential difference is obtained by inputting the voltage across the current detection resistor 37 to the differential amplifier. After the obtained potential difference is converted into digital data by the A / D converter 38 of the microcomputer, the motor current value 33 is obtained by dividing by a predetermined resistance value of the current detection resistor (current conversion calculation 39). As described above, the motor current value 33 is compared with the target current value as a feedback value.

  In FIG. 1, a motor 7 is mounted on a seat belt device (not shown in FIG. 1), and includes an overheat protection means 8 and a motor temperature detection means 9 inside. As described above, a thermal protector that is small and lightweight is used for the overheat protection means 8. When the thermal protector is heated and exceeds the operating temperature (for example, 120 ° C.), the internal thermal responder is activated, and the contact is opened to temporarily interrupt the circuit. Thereafter, when the temperature is lowered to the return temperature (for example, 70 ° C.) of the thermally actuated body, the contact is automatically closed and energized. It is desirable to use a temperature sensor such as a thermocouple or a thermistor for the motor temperature detecting means 9 for measuring the temperature inside the motor. However, any method may be used as long as the temperature detecting means can be incorporated in the motor. . The motor overheat determination means 10 determines whether the motor is in an overheated state based on the motor temperature acquired from the motor temperature detection means 9. When the overheat determination condition is set to 100 ° C., for example, based on a predetermined operating temperature (120 ° C.) possessed by the thermal protector used in the overheat protection means 8, the motor temperature is less than 100 ° C., the motor normal state, 100 ° C. or more Is determined as a motor overheat state. Moreover, in the return from the motor overheated state to the motor normal state, the determination condition is set to 80 ° C., for example, and only when the motor temperature falls below the determination condition, the motor overheat state is returned to the motor normal state. A judgment method with hysteresis is desirable. The motor overheat determination means 10 can be determined using an electronic circuit, but is preferably determined using a microcomputer used in the seat belt motor control means 4. When a microcomputer is used, the determination value can be easily changed. Furthermore, the reduction in circuit leads to a reduction in mounting area and cost. It should be noted that the overheat determination temperature and the normal determination temperature are desirably determined after actually performing a test in consideration of various conditions.

  The microcomputer used in the seat belt motor control unit 4 executes the following control flow based on the first and second alarm signals from the alarm unit 3 and the overheat determination result from the motor overheat determination unit 10. FIG. 4 is a control flowchart executed by the microcomputer. The process up to outputting the first alarm signal and the second alarm signal is as described above with reference to FIG. In step S1, it is confirmed which of the first and second alarm signals is the output signal of the alarm means 3 is. In the case of the first alarm signal, the process proceeds to step S2 to determine overheating of the motor. If the result of the determination is an overheated state, the above processing is continued until the second alarm signal is generated or the motor is determined to be in the normal state by returning to the alarm confirmation processing in step S1 without performing the subsequent motor drive processing. Repeatedly. If the normal state is determined in step S2, the target current for the first alarm (the motor current C1 shown in FIG. 2C) is set in step S3, and the drive time for the first alarm (the (( The time T2) shown in c) is set. If the second alarm signal is detected in step S1, the target current value of the second alarm is set in step S4 and the second alarm is set in step S6, as in the processes in steps S3 and S5. Motor driving time (motor current C2 and time T3 shown in FIG. 2C) is set. After the setting of the target current value and the motor driving time is completed, the motor 7 is driven for a predetermined time to wind the seat belt (steps S7 to S9).

  By executing the above control flow, it is possible to avoid a state in which the motor drive caused by the overheat protection function is disabled. And when a 2nd warning generate | occur | produces, it becomes possible to wind up a seat belt reliably and to restrain a passenger | crew.

Embodiment 2. FIG.
In the first embodiment, as a method for avoiding the state where the motor drive caused by the overheat protection function is disabled, the first alarm is generated in order to suppress the heat generation of the motor while it is determined that the motor is in the overheat state. The seat belt winding was stopped. However, in this case, the warning cannot be notified to the driver. An apparatus for solving this problem will be described in the second embodiment.

  FIG. 5 is a control flowchart of the microcomputer according to the second embodiment, and FIG. 6 is a diagram showing the heat generation amount of the motor at the first and second alarms. 5 and FIG. 6, the same reference numerals as those in FIG. 4 and FIG. If it is determined in step S2 of FIG. 5 that the motor is in an overheated state, the process proceeds to step S51, where a low target current value is set that is lower than the target current value set in step S3. For example, as shown in FIG. 6A, a low target current value C3 corresponding to 50% of the target current value C1 in the normal state set in step S3 is set in step S51. Accordingly, when the motor driving time T2 is the same, the heat generation amount 61 of the motor can be suppressed to 50% of the normal heat generation amount (21).

It is also possible to suppress the heat generation amount of the motor by changing the motor driving time to a low driving time in step S52 without changing the target current value set in step S51. As shown in FIG. 6B, the target current value set in step S52 is the same as the target current value C1 set in step S3. For example, the motor low drive time T4 is set to the normal motor drive time T2. As described above, the heat generation amount 62 of the motor can be suppressed to 50% of the normal heat generation amount (21). As shown in the second embodiment, the amount of heat generated by the motor can be suppressed by limiting the target current value or motor driving time during motor driving. Therefore, the overheat protection function does not operate, and it is possible to notify a bodily sensation alarm when the first alarm is generated.

Embodiment 3 FIG.
In the first embodiment and the second embodiment, the temperature inside the motor is directly measured using a thermocouple or a thermistor. However, in reality, disposing a thermocouple or thermistor inside the motor requires descriptive measures. Therefore, in this third embodiment, an apparatus for indirectly estimating the motor temperature based on the motor current value without mounting the motor temperature detecting means inside the motor will be described.

  FIG. 7 is a block diagram showing a configuration of an occupant restraint device according to another embodiment of the present invention. Since the same reference numerals as those in the previous embodiment denote the same or corresponding parts, the description thereof is omitted. In FIG. 7, the motor ambient temperature detecting means 71 is a device for measuring the temperature around the motor 7 that drives the seat belt, and is intended to obtain the ambient temperature around the motor. Therefore, in addition to being able to easily measure the ambient temperature by using the thermistor and the thermocouple described above, paying attention to the fact that the seat belt motor 7 is installed in the passenger compartment, an indoor thermometer equipped in the vehicle It is also possible to utilize the temperature value. The motor temperature calculation means 9 a calculates the motor temperature from the motor current value acquired from the seat belt motor control means 4 and the ambient temperature from the motor ambient temperature detection means 71. The motor ambient temperature detection means 71 and the motor temperature calculation means 9a constitute a motor temperature acquisition means.

  Next, an outline of a method for calculating the motor temperature using the motor current value will be described. From the motor current value I acquired from the seat belt motor control means 4 and the predetermined resistance value R possessed by the motor coil, the heat generation amount Q1 of the coil is obtained by the following equation (1).

Q1 = I * I * R * t (1)
(t: Time [sec])

  Furthermore, using the calorific value Q and a predetermined heat capacity C (= specific heat c * mass m) of the motor, it can be converted into a temperature increase ΔT by the following equation (2).

      ΔT = Q1 / heat capacity C (2)

  Therefore, the temperature obtained by adding the temperature increase ΔT to the ambient temperature detected by the motor ambient temperature detecting means 71 can be estimated as the motor temperature. Further, in determining the heat generation amount Q1 of the motor coil, the heat amount Q2 lost by the heat conduction to the seat belt module to which the motor is attached and the heat amount Q3 lost by the coil due to heat radiation to the atmosphere are obtained and stored in advance. The motor temperature can be estimated with higher accuracy by subtracting from the heat generation amount Q1 of the motor coil. With the configuration in this embodiment, it is not necessary to install a temperature sensor in the motor, and the motor temperature can be acquired with a simple configuration. The motor temperature calculation means 9a may also be configured in the microcomputer of the seat belt motor control means 4.

As described above, when the motor is in an overheated state when the first alarm signal is generated, the motor drive caused by the overheat protection function is temporarily stopped by temporarily stopping the winding of the seat belt with the first motor torque. Since the impossible state can be avoided, the seat belt can be reliably wound when the second alarm signal is generated.
Further, when the motor is overheated when the first alarm signal is generated, the state where the motor driving caused by the overheat protection function is disabled can be avoided by winding the seat belt by weakening the first motor torque. Therefore, the seat belt can be reliably wound when the second alarm signal is generated.
Also, if the motor is in an overheated state when the first alarm signal is generated, a state in which the motor drive caused by the overheat protection function is disabled can be avoided by limiting the time for winding the seat belt with the first motor torque. Therefore, the seat belt can be reliably wound when the second alarm signal is generated.
Furthermore, the motor temperature can be obtained easily by installing the motor temperature detection means inside the motor, and the motor temperature can be estimated indirectly based on the motor current value. The motor temperature detecting means need not be installed in the motor, and the temperature can be obtained with a simple configuration.

It is a block diagram which shows the structure of the passenger | crew restraint apparatus by one embodiment of this invention. It is a graph for demonstrating an example of operation | movement of the passenger | crew restraint apparatus by this invention. It is a block diagram which shows the outline | summary of an example of the feedback control of the passenger | crew restraint apparatus by this invention. It is a flowchart for demonstrating an example of operation | movement of the seatbelt motor control means of the passenger | crew restraint apparatus by this invention. It is a flowchart for demonstrating another example of operation | movement of the seatbelt motor control means of the passenger | crew restraint apparatus by this invention. It is a graph for demonstrating another example of operation | movement of the passenger | crew restraint apparatus by this invention. It is a block diagram which shows the structure of the passenger | crew restraint apparatus by another embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 Obstacle detection means, 2 Collision risk calculation means, 3 Alarm means, 4 Seat belt motor control means, 5 Motor drive means, 6 Motor current detection means, 7 Motor, 8 Overheat protection means, 9 Motor temperature detection means, 9a Motor temperature calculation means, 10 motor overheat determination means, 71 motor ambient temperature detection means.

Claims (5)

Warning means for outputting a first warning signal and a second warning signal indicating that the danger level is higher based on the risk of collision with an obstacle ahead of the vehicle;
A motor that winds up a seat belt having an overheat protection means that cuts off the supply of power when a predetermined temperature is exceeded;
A seat belt motor that calculates a control amount to wind up the seat belt with a first motor torque and a larger second motor torque in accordance with the first and second alarm signals, and outputs a control signal indicating this. Control means;
Motor driving means for generating a voltage required for motor driving based on a control signal output by the seat belt motor control means;
Motor temperature acquisition means for detecting the motor temperature or estimating the corresponding temperature;
Motor overheat determination means for determining that the motor is in an overheated state when the motor temperature of the motor temperature acquisition means exceeds a preset threshold value based on the operating temperature of the overheat protection means;
And when the seat belt motor control means determines that the motor is overheated by the motor overheat determination means when the alarm means outputs the first alarm signal, the first motor torque When the alarm means outputs a second alarm signal, the motor overheat determination means determines that the motor is overheated. Even if it is carried out , the passenger | crew restraint apparatus characterized by winding up a seatbelt with a 2nd motor torque. Warning means for outputting a first warning signal and a second warning signal indicating that the danger level is higher based on the risk of collision with an obstacle ahead of the vehicle;
A motor that winds up a seat belt having an overheat protection means that cuts off the supply of power when a predetermined temperature is exceeded;
A seat belt motor that calculates a control amount to wind up the seat belt with a first motor torque and a larger second motor torque in accordance with the first and second alarm signals, and outputs a control signal indicating this. Control means;
Motor driving means for generating a voltage required for motor driving based on a control signal output by the seat belt motor control means;
Motor temperature acquisition means for detecting the motor temperature or estimating the corresponding temperature;
Motor overheat determination means for determining that the motor is in an overheated state when the motor temperature of the motor temperature acquisition means exceeds a preset threshold value based on the operating temperature of the overheat protection means;
When the seat belt motor control means determines that the motor is overheated by the motor overheat determination means when the alarm means outputs the first alarm signal, the first motor When a control signal for winding the seat belt is output with a motor torque that is weaker than the torque , and the alarm means outputs a second alarm signal, the motor overheat is determined by the motor overheat determination means. An occupant restraint device that winds up a seat belt with a second motor torque even when it is determined to be in a state . Warning means for outputting a first warning signal and a second warning signal indicating that the danger level is higher based on the risk of collision with an obstacle ahead of the vehicle;
A motor that winds up a seat belt having an overheat protection means that cuts off the supply of power when a predetermined temperature is exceeded;
A seat belt motor that calculates a control amount to wind up the seat belt with a first motor torque and a larger second motor torque in accordance with the first and second alarm signals, and outputs a control signal indicating this. Control means;
Motor driving means for generating a voltage required for motor driving based on a control signal output by the seat belt motor control means;
Motor temperature acquisition means for detecting the motor temperature or estimating the corresponding temperature;
Motor overheat determination means for determining that the motor is in an overheated state when the motor temperature of the motor temperature acquisition means exceeds a preset threshold value based on the operating temperature of the overheat protection means;
And when the seat belt motor control means determines that the motor is overheated by the motor overheat judgment means at the time when the warning means outputs the first warning signal, the driving time of the motor is determined. When the control signal for winding the seat belt with the first motor torque is shortened and the alarm means outputs the second alarm signal, the motor overheat determination means determines that the motor is overheated. An occupant restraint device that winds up the seat belt with the second motor torque even if it is determined .   The occupant restraint apparatus according to any one of claims 1 to 3, wherein the motor temperature acquisition means includes motor temperature detection means arranged in the motor.   The motor temperature acquisition means comprises motor ambient temperature detection means for detecting the motor ambient temperature, and motor temperature calculation means for obtaining the motor temperature by adding the rising temperature estimated based on the motor current and the motor ambient temperature. The occupant restraint device according to any one of claims 1 to 3.

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