JP4189983B2 - Seat belt drive - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a seat belt driving apparatus using the driving circuits of the DC motor.
[0002]
[Prior art]
A seat belt used in a passenger car is given tension by a seat belt winder. That is, when using a seat belt, a person pulls out the seat belt wound by the spring in the seat belt winder and engages with the other seat belt fixed to the seat by the buckle. Thereafter, when the hand is loosened, the seat belt which is loosened by the action of the spring of the seat belt winder is wound up, and the tension determined by the spring is applied to the seat belt to restrain the occupant to the seat.
[0003]
However, in such a spring-type take-up mechanism, a force is applied only in the direction in which the seat belt is tightened. Therefore, when a person tries to loosen the seat belt, the seat belt must be pulled against this force. There was a point. Further, since the elastic force of the spring is used, the operation is unstable, and winding failure may occur.
[0004]
[Problems to be solved by the invention]
In order to solve such a problem, the inventor's colleague can easily relax the restraint force by pulling the seat belt by a human and can deal with flexible winding control. An invention relating to a seat belt driving device was made and a patent application was filed as a patent application No. 126242 in 1999 (hereinafter referred to as a prior invention). That is, a DC motor is used to drive the seat belt, and PWM control or pulse width constant / variable cycle control is performed to control the rotation direction and rotation speed of the DC motor.
[0005]
An example of the embodiment of the prior invention is shown in FIG. Although not shown, a seat retractor is coupled to the motor M, and the rotation of the motor M causes the seat belt to be wound or unwound.
[0006]
Control pulses P1 to P4 are supplied from the CPU to the gates of switching transistors Q1 to Q4, which are switching elements, as P1 'to P4' via a gate circuit GATE. On the other hand, the voltage from the DC power source is connected to the collectors of the switching transistors Q1 and Q2, the motor terminal A is connected to the emitter of the transistor Q1 and the collector of the transistor Q4, and the motor terminal B is connected to the emitter of the transistor Q2 and the collector of the transistor Q3. Has been. Further, the emitters of the switching transistors Q3 and Q4 are grounded.
[0007]
When the buckle of the seat belt is engaged and external information such as the rotation direction and rotation speed of the motor M is input, the CPU outputs control pulses P1 to P4 accordingly. FIG. 3 shows an example of a method for outputting the control pulses P1 to P4 when the motor M is rotated in the forward direction. In (a), the control pulse P3 is kept at a high level, and the control pulse P1 is turned on and off (hereinafter, ON is a high level and OFF is a low level). Thereby, the switching transistors Q2 and Q4 are turned off, Q3 is turned on, and Q1 is repeatedly turned on and off. Therefore, the current from the DC power supply flows in the order of Q1 → motor terminal A → motor terminal B → Q3 → ground in synchronization with the on / off of the switching transistor Q1, and the winding current flowing from the terminal A side to the B side flows to the motor M. Given. Thereby, the motor M rotates forward.
[0008]
In (b), the control pulse P1 is kept high and the control pulse P3 is turned on / off. Thereby, the switching transistors Q2 and Q4 are turned off, Q1 is turned on, and Q3 is repeatedly turned on and off. Therefore, the current from the DC power source flows in the order of Q1 → motor terminal A → motor terminal B → Q3 → ground in synchronization with the on / off of the switching transistor Q3, and the winding current flowing from the terminal A side to the B side flows to the motor M. Given. Thereby, the motor M rotates forward.
[0009]
In (c), the control pulses P1 and P3 are turned on and off in synchronization. Thereby, the switching transistors Q2 and Q4 are turned off, and Q1 and Q3 are repeatedly turned on and off. Therefore, the current from the DC power supply flows in the order of Q1 → motor terminal A → motor terminal B → Q3 → ground in synchronization with the on / off of the switching transistors Q1 and Q3, and the winding flowing in the motor M from the terminal A side to the B side. Current is applied. Thereby, the motor M rotates forward.
[0010]
FIG. 4 shows an example of a method for outputting the control pulses P1 to P4 when the motor M is rotated in the reverse direction. In (a), the control pulse P4 is kept at a high level, and the control pulse P2 is turned on and off. Thereby, the switching transistors Q1 and Q3 are turned off, Q4 is turned on, and Q2 is repeatedly turned on and off. Therefore, the current from the DC power source flows in the order of Q2 → motor terminal B → motor terminal A → Q4 → ground in synchronization with the on / off of the switching transistor Q2, and the winding current flowing from the terminal B side to the A side flows to the motor M. Given. As a result, the motor M reverses.
[0011]
In (b), the control pulse P2 is kept at the high level, and the control pulse P4 is turned on / off. Thereby, the switching transistors Q1 and Q3 are turned off, Q2 is turned on, and Q4 is repeatedly turned on and off. Therefore, the current from the DC power supply flows in the order of Q2 → motor terminal B → motor terminal A → Q4 → ground in synchronization with the on / off of the switching transistor Q4, and the winding current flowing from the terminal B side to the A side flows to the motor M. Given. Thereby, the motor M rotates forward.
[0012]
In (c), the control pulses P2 and P4 are turned on and off in synchronization. Thereby, the switching transistors Q1 and Q3 are turned off, and Q2 and Q4 are repeatedly turned on and off. Therefore, the current from the DC power source flows in the order of Q2 → motor terminal B → motor terminal A → Q4 → ground in synchronization with the on / off of the switching transistors Q2 and Q4, and the winding that flows from the terminal B side to the A side to the motor M. Current is applied. As a result, the motor M reverses.
[0013]
When changing the rotation speed of the motor, as shown in FIG. 5, the pulse width (T2) of the on / off pulse is made constant and the pulse rate (cycle corresponding to T1) is changed, or the pulse rate is made constant (cycle T1). And the duty ratio (T2 / T1) is changed.
[0014]
When the motor is not driven, the control pulses P3 and P4 (or the control pulses P1 and P2) are kept on as shown in FIG. 6 in order to make the motor M difficult to rotate by external force. As a result, no voltage from the DC power source is applied to the motor M, but when the motor M tries to rotate by an external force, a regenerative current flows through the switching transistors Q3 and Q4 by the electromotive force, and the motor M It becomes difficult to rotate.
[0015]
Conversely, when the motor M is easily rotated by an external force, the control pulse is turned off. As a result, the regenerative current of the motor M does not flow and regenerative braking is not applied, so that the seat belt can be moved lightly.
[0016]
In FIG. 2, the thermistor TH monitors the temperature of the motor M, and when the motor M is overloaded and the temperature rises, the information is input to the CPU, and the CPU stops driving the motor M. Is provided. The flywheel diode connected in parallel with the motor M is not shown.
[0017]
Thus, according to the prior invention, the seat belt can be driven in the required direction at the required speed, so that the driving of the seat belt rich in flexibility can be realized.
[0018]
However, when driving the seat belt, in addition to the general driving, a situation occurs in which the winding must be performed with a torque larger than usual. For example, when a collision is predicted, it is necessary to wind up the slack of the belt rapidly and restrain the person to the seat with a force stronger than usual. Further, when a child seat is fixed to a seat with a seat belt, it is necessary to fix the child seat firmly with a stronger force than to restrain a person, and a large torque is required. Such a winding state is referred to as “forced winding” in this specification, and is distinguished from normal winding.
[0019]
Of course, also in forced winding, the necessary motor torque can be obtained by using a drive circuit as shown in FIG. 2 and increasing the duty ratio of the drive pulse. However, in that case, in the case of normal winding, the duty ratio is small and the controllability is deteriorated. In addition, originally, the duty ratio in the case of normal winding should be increased to some extent and a switching transistor with a smaller capacity should be used. There is a problem in that a switching transistor having a large capacity is required and the cost of the circuit is increased.
[0020]
The present invention has been made in view of such circumstances, and it is an object of the present invention to provide a seat belt drive device that can cope with forced winding while using a switching element that can handle only normal winding. To do.
[0021]
[Means for Solving the Problems]
A first means for solving the problem includes a DC motor drive circuit , a DC motor driven by the DC motor drive circuit, and a seat belt retractor driven by the DC motor. A seat belt drive device capable of switching between normal winding for supplying current used for the DC motor to the DC motor and forced winding for supplying current larger than the current used for the DC motor to the DC motor. , the DC motor driving circuit, a switching circuit for supplying to said DC motor in place of the pulse voltage to DC voltage, and a control circuit for changing the duty ratio of the DC pulse voltage generated by said switching circuit, to the DC motor a circuit for supplying a direct current power source without passing through the switching circuit, set the circuit for supplying said direct current power supply Is, and a closable contacts by the control circuit, the control circuit, wherein the time of normal winding, the control to open the contacts, the pulse voltage supplied to the DC motor by the switching circuit When the forced winding signal is input from the outside, the contact is closed and controlled, and the direct-current power supply is directly connected to the direct-current motor without passing through the switching circuit. A seat belt driving device characterized by being supplied .
[0022]
In this means, when a current that is constantly used is supplied to the motor as in normal winding, the current is supplied to the motor while being controlled by a switching circuit. Then, when a current larger than the current that is used regularly is required as in the case of forced winding, the current is directly supplied from the power source to the motor without passing through the switching circuit. If a large current is supplied via a relay or the like, a large current can be supplied without using an expensive element. By this means, the duty ratio of the pulse voltage when used constantly can be increased, so that the controllability is not deteriorated and the capacity of the switching element does not need to be increased.
[0024]
Further, since the motor driving circuit mainly including a switching element having a capacity corresponding to normal winding can also perform forced winding, a small and inexpensive seat belt driving device can be obtained.
According to a second means for solving the above-mentioned problem, in the first means, the control circuit closes and controls the contact at the time of the forced winding corresponding to the collision prediction or when the child seat is fixed to the seat. The seat belt driving apparatus is characterized in that direct current power is directly supplied to the direct current motor by a circuit for supplying direct direct current power.
Thus, even when a collision is predicted or when the child seat is fixed to the seat with the seat belt, the child seat can be securely fixed with a strong force.
According to a third means for solving the above-mentioned problem, in the first means or the second means, the contact is between the direct-current motor and the direct-current power supply in a circuit for supplying the direct direct-current power. A first relay contact provided in a portion, and a second relay contact provided in a portion between the DC motor and a ground portion of the circuit for supplying the direct DC power, and the control circuit includes the forced winding A seat belt drive characterized by closing and controlling the first relay contact and the second relay contact by energizing a relay coil for driving the first relay contact and the second relay contact at the time of taking. Device.
As a result, a continuous current is supplied from the DC power source through the path of DC power source → first contact → motor terminal → second contact → ground, and the DC motor can rotate at full torque to forcibly wind up the seat belt. .
According to a fourth means for solving the above problem, in any one of the first to third means, the temperature of the DC motor is monitored, and when the DC motor is overloaded, corresponding information is sent to the control circuit. The seat belt driving apparatus according to claim 1, further comprising a thermistor for outputting, wherein the control circuit stops driving the DC motor when information corresponding to the overload is input from the thermistor.
Thereby, when the DC motor is overloaded and the temperature rises, the information can be input to the control circuit, and the driving of the DC motor can be stopped by the control circuit.
[0025]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an outline of a drive motor and its control device used in a seat belt drive device which is an example of an embodiment of the present invention.
[0026]
Most of FIG. 1 is the same as the embodiment of the invention of the prior application shown in FIG. 2, and only the place where the relay X is provided is different. When normal winding control is performed, no power is supplied from the CPU to the coil of the relay X, and the contacts x1 and x2 are open. The operation of this circuit during normal winding is the same as the operation shown in the description of the prior invention shown in FIG.
[0027]
When a forced winding signal is input to the CPU as external information, the CPU turns off all the pulses P1 to P4 and applies a voltage to the relay X coil. Then, the contacts x1 and x2 of the relay X are closed, and a continuous current is supplied from the DC power source through the DC power source → contact x1 → motor terminal A → motor terminal B → contact x2 → ground path, and the motor M is positive with full torque. Turn the seat belt to force it.
[0028]
In this circuit, the motor M and the DC power source capacity need only be able to handle the torque required for forced winding, and the switching transistors Q1 to Q4 have a capacity sufficient to pass the current required for normal winding. Is enough. In addition, the switching transistors Q1 to Q4 can increase the duty ratio of the pulse current during normal winding by improving the controllability by setting the capacity to allow the current necessary for normal winding to flow. it can.
In the above embodiment, a relay is used, but a semiconductor element such as a thyristor may be used.
[0029]
【The invention's effect】
As described above, in the invention according to claim 1 of the present invention, when a current larger than the current that is constantly used is required, the current is directly supplied from the power source to the motor without passing through the switching circuit. As a result, the capacitance of the elements of the switching circuit can be reduced, the cost can be reduced, and the duty ratio of the pulse during steady use can be increased, so that controllability does not have to be deteriorated.
[0030]
In the invention according to claim 2, since it is possible to perform forced winding with a motor drive circuit mainly composed of a switching element having a capacity corresponding to normal winding, a small and inexpensive seat belt driving device can be obtained. it can.
[Brief description of the drawings]
FIG. 1 is a diagram showing an outline of a drive motor and its control device used in a seatbelt drive device which is an example of an embodiment of the present invention.
FIG. 2 is a schematic diagram showing a circuit configuration of a motor drive circuit according to an embodiment of the invention of the prior application.
FIG. 3 is a diagram illustrating an example of a control pulse output method when a motor is rotated in a positive direction.
FIG. 4 is a diagram illustrating an example of a control pulse output method when a motor is rotated in the reverse direction.
FIG. 5 is a diagram illustrating a duty ratio of a control pulse.
FIG. 6 is a diagram illustrating an example of a state of a control pulse when the motor is difficult to rotate due to an external force.
[Explanation of symbols]
CPU: microcomputers P1 to P6, P1 'to P4': control output (pulse)
GATE: gate circuits Q1 to Q4: switching transistor M: motor C1, C2: capacitor L: reactance RL, RL2: relay TH: thermistor SW: CPU switch X: relay (relay coil)
x1, x2: Relay contact

Claims (4)

A DC motor drive circuit;
A direct current motor driven by the direct current motor drive circuit;
A seat belt retractor driven by the DC motor,
A seatbelt drive device capable of switching between normal winding for supplying a constant current to the DC motor and forced winding for supplying a current larger than the constant current to the DC motor. There,
The DC motor drive circuit is
A switching circuit for supplying to said DC motor in place of the pulse voltage a DC voltage,
A control circuit for changing a duty ratio of a DC pulse voltage generated by the switching circuit;
A circuit for supplying a direct current power source without passing through the switching circuit to the DC motor,
Provided in the circuit for supplying the direct DC power, and has a contact that can be opened and closed by the control circuit ,
The control circuit includes:
At the time of the normal winding, the contact is opened and controlled, and the pulsed voltage is supplied to the DC motor by the switching circuit,
At the time of forced winding when an external forced winding signal is input, the contact is closed and controlled, and direct DC power is supplied to the DC motor without passing through the switching circuit by the circuit that supplies the direct DC power. A seatbelt drive device characterized by:   The seatbelt drive device according to claim 1, wherein
  The control circuit includes:
  When the collision is predicted or when the child seat is fixed to the seat, the contact is closed and controlled, and the direct current power is supplied to the direct current motor by the circuit for supplying the direct current power.
A seat belt drive device characterized by that.   In the seatbelt drive device according to claim 1 or 2,
  The contact includes a first relay contact provided in a portion between the DC motor and the DC power supply in the circuit for supplying the direct DC power supply, and the DC motor and ground in the circuit for supplying the direct DC power supply. A second relay contact provided in a part between the parts,
  The control circuit includes:
  At the time of the forced winding, the first relay contact and the second relay contact are closed and controlled by energizing the relay coil for driving the first relay contact and the second relay contact.
A seat belt drive device characterized by that.   The seatbelt drive device according to any one of claims 1 to 3,
  A thermistor that monitors the temperature of the DC motor and outputs corresponding information to the control circuit when the DC motor is overloaded;
  The control circuit includes:
  When the information corresponding to the overload is input from the thermistor, the DC motor is stopped.
A seat belt drive device characterized by that.

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