Seat belt system

A seat belt system includes a prohibition means for preventing a sliding block connected to one end of a seat belt from moving when the vehicle is rapidly decelerated and confirmation means for confirming the connection between connectors provided in the prohibition means. The confirmation means a connector, 4-pin and a short circuit provided between two pins of the connector so as to be opposite to the detecting switch provided between the other pins of the connector.

BACKGROUND OF THE INVENTION 
1. FIELD OF THE INVENTION 
The present invention relates to a seat belt system, particularly to a 
passive seat belt system which automatically causes a seat belt to move 
between a fitted position, in which the occupant is restricted by means of 
the seat belt, and a release position, in which the occupant is not 
restricted by means of the seat belt, when the occupant is getting in and 
out of a vehicle. 
2. DESCRIPTION OF THE PRIOR ART 
The Japanese Patent First Publication Showa 56-71643 discloses a passive 
seat belt system. In this system, a guide rail is mounted on the roof side 
rail of a vehicle. A sliding block, which is slidable on the guide rail, 
is provided at one end of a seat belt. The sliding block is connected to 
one end of an actuation wire and the other end of the actuation wire is 
drivingly associated with a drive motor for driving the sliding block 
along the guide rail. Therefore, one end of the seat belt can move along 
the guide rail according to the movement of the sliding block which is 
driven by the drive motor via the actuation wire. In addition, a latch 
base is provided at one end of the guide rail on the side of the drive 
motor, i.e. at the rear end of the guide rail. When the sliding block is 
moved from the front end of the guide rail, i.e. the release position, to 
the position of the latch base, i.e. the fitted position, an engaging 
portion, which is provided at the tip of the sliding block, is latched by 
means of the latch base. The movement of the sliding block is completed at 
this position, so that the occupant is restricted by means of the seat 
belt. 
The movement of the sliding block is controlled by a control circuit which 
includes a door switch and two limit switches. The door switch comprises 
two stationary terminals and a movable contact which is movable between 
the stationary terminals in accordance with opening and closing of the 
door. One of the stationary terminals, to which the movable contact 
contacts while the door is opened, will be hereafter referred to as "door 
open position detecting terminal". The other stationary terminal, to which 
the movable contact contacts while the door is closed, will be hereafter 
referred to as "door closed position detecting terminal". 
One of the limit switches is oriented adjacent the front end of the guide 
rail for detecting the sliding block at the front end. This limit switch 
will be thus referred as "front end position detecting switch". The other 
limit switch is positioned adjacent the rear end of the guide rail for 
detecting the sliding block at the rear end. This limit switch is thus 
referred to as "rear end position detecting switch". In addition, the 
control circuit includes a sensor which becomes ON to restrict the 
movement of the sliding block when the vehicle is rapidly decelerated, 
such as upon collision of the vehicle. 
In order to assure emergency safety operation of the seat belt, inspection 
has to be performed after installation of the seat belt system to the 
vehicle or after completion of assembling of the vehicle. A difficulty of 
inspection is encountered. Normally, unless emergency condition, such as 
collision, occurs to cause rapid deceleration of the vehicle, the sensor 
will be held OFF to maintain the seat belt system at initial position. On 
the other hand, when the connection between the sensor and the control 
circuit is broken, no trigger signal to actuate the seat belt system will 
be input to hold the seat belt system at the initial. position. Therefore, 
inspection has to be performed under emergency condition in which the seat 
belt system becomes active when the sensor is connected. In practice, to 
turn the sensor ON, substantial deceleration has to be applied to the 
vehicle. This requires substantially high skill in checking emergency seat 
belt locking condition. 
SUMMARY OF THE INVENTION 
It is therefore a principal object of the present invention to eliminate 
the aforementioned disadvantage and to provide a seat belt system in which 
the connection state of a slider restricting means including a sensor can 
be easily checked. 
In order to accomplish the aforementioned and other specific objects, a 
seat belt system, according to the present invention, employs an electric 
circuit establishing an emergency lock for a seat belt for restricting a 
vehicular seat occupant upon emergency condition of the vehicle. The 
electric circuit includes a sensor means for detecting rapid deceleration 
of the vehicle. The electric circuit becomes active to establish the 
emergency lock when the sensor means detects the rapid deceleration of the 
vehicle. The circuit further includes an indicator connected to the sensor 
means and a common circuit which is also connected to a switch which is 
switchable between ON and OFF. The indicator is so arranged as to turn ON 
in response to turning ON of said switch while said sensor means is 
correctly connected in said electric circuit. 
According to one aspect of the present invention, the seat belt system 
comprises: 
a seat belt for restricting the occupant; 
drive means for causing the seat belt to move between a fitted position, in 
which the occupant is restricted by means of the seat belt, and a release 
position, in which the occupant is released from the seat belt; 
control means for controlling the movement of the seat belt; 
prohibition means for preventing the seat belt from moving from the fitted 
position to the release position for a predetermined time when the vehicle 
speed is rapidly decreased; and 
confirmation means for confirming the connection of the prohibition means. 
The prohibition means may comprise a detecting switch which becomes ON to 
restrict the movement of the seat belt when the vehicle collides with an 
object or when the vehicle speed is rapidly decreased. The detecting 
switch is preferably a sensor. The seat belt may be provided with a 
sliding block, which is slidable on a guide rail extending longitudinally 
along the edge of the roof of the vehicle, at one end thereof. The drive 
means may cause the sliding block to move between the front and rear ends 
of the guide rail. The drive means preferably comprises a drive motor and 
an actuation wire which is provided within the guide rail so that one end 
of the actuation wire is fixed to the sliding block and the other end of 
the actuation wire is fixed to the drive motor. The sliding block is 
preferably latched by means of a latch base at the rear end of the guide 
rail in order to restrict the occupant. The confirmation means may 
comprise a 4-pin connector and a short circuit provided between two pins 
of the connector. In this case, the detecting switch is preferably 
provided between the other two pins of the connector so as to be opposite 
to the short circuit. The short circuit may be connected to a warning 
means and an active belt switch, which becomes OFF when the manually 
operated seat belt restricting the waist of the occupant is set and which 
becomes ON when the seat belt is removed, in series. The warning means may 
be warning lamp emitting light or a chime producing a warning noise. In 
addition, a timer circuit, which supplies power to the warning means for a 
predetermined time when the active belt switch becomes ON, may be provided 
between the warning means and the active belt switch. The control means 
may comprise a door switch, which becomes ON when the door is opened and 
which becomes OFF when the door is closed, and front and rear limit 
switch, which, respectively, become ON when the sliding block arrives at 
the front and rear ends of the guide rail. The short circuit may be 
connected to the door switch in series.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
Referring now to the drawings, particularly to FIGS. 1 and 2, the first 
preferred embodiment of a seat belt system, according to the present 
invention, is described below. 
As shown in FIG. 1, a guide rail 12 is provided to extend along the upper 
edge of a door opening of vehicle body 10. In the preferred construction, 
the guide rail 12 is mounted on the roof side rail of the vehicle body 10. 
The guide rail 12 has the front end located adjacent a front pillar and 
the rear end terminating adjacent a center pillar of the vehicle body 10. 
A sliding block 14 can slidably engage the guide rail 12. The sliding 
block 14 slides along the guide rail 12 between the front and rear end of 
the guide rail 12. The sliding block 14 carries one end of a seat belt 16. 
The other end of the seat belt 16 is connected to a retractor which is 
fixedly secured to the side of a seat near the longitudinal center of the 
vehicle body 10. The seat belt 16 may be wound onto the retractor in per 
se well known manner. The sliding block 14 is also secured to one end of 
an actuation wire 18, for example, a spiral actuation wire. The actuation 
wire 18 is movable along the guide rail 12. The other end of the actuation 
wire 18 is drivingly cooperated with a drive motor 20. Various driving 
mechanism may be taken for drivingly coupling the actuation wire 18 to the 
drive motor 20. In the shown embodiment, the portion of the actuation wire 
18 is designed to mesh with a drive pinion or gear to be driven in axial 
direction of the actuation wire. Therefore, one end of the seat belt 16 
can move along the guide rail 12 with the sliding block 14 when the 
actuation wire 18 is driven by the drive motor 20. When the vehicular door 
opens, the sliding block 14 is positioned at the front end of the guide 
rail. At this sliding block position, the seat belt is held away from the 
corresponding seat to allow a passage to get into and off the vehicle 
cabin. This sliding block and seat belt position is hereafter referred to 
as "release position". On the other hand, when the door is closed, the 
sliding block 14 is held at the rear end of the guide rail 12. At this 
position, the seat belt is held to be fitted on a vehicular seat occupant. 
This sliding block or seat belt position is hereafter referred to as 
"fitted position". In addition, a latch base 22 is provided at the rear 
end of the guide rail 12. When the sliding block 14 is moved from the 
position shown in FIG. 1, i.e. the release position to the fitted 
position, an engaging portion, which is provided at the tip of the sliding 
block 14, is latched on the latch base 22. The movement of the sliding 
block 14 is finished at this position, so that the seat belt is held at 
fitted position. 
The revolution of the drive motor 20 is controlled by a control circuit 24 
which includes front and rear limit switches 28 and 30, relays 32, 34 and 
36, transistors 38, 40, 42 and 44, diodes 46 and 48 and resistors r.sub.1 
to r.sub.8. The relay 32 comprises a relay coil 50, stationary terminals 
52 and 54 and a movable contact 56 which can move between the stationary 
terminals by the relay coil 50. When electrical current runs through the 
relay coil 50, the movable contact 56 is in communication with the 
stationary terminal 52, and when no electrical current runs through the 
relay coil 50, the movable contact 56 is in communication with the 
stationary terminal 54 which is connected to ground. Similarly the relay 
34 comprises a relay coil 58, stationary terminals 60 and 62 and a movable 
contact 64 which is movable between the stationary terminals 60 and 62 by 
the relay coil 58. When electrical current runs through the relay coil 58, 
the movable contact 64 is in communication with the stationary terminal 62 
and, when no electrical current runs through the relay coil 58, the 
movable contact 64 is in communication with the stationary terminal 60 
which is connected to ground. A door switch 26, which is connected to the 
control circuit 24, turns ON and OFF when the door is opened and closed, 
respectively. The front and rear limit switches 28 and 30 are arranged at 
the front and rear ends of the guide rail 12, and respectively become OFF 
when the sliding block 14 arriving the corresponding positions is 
detected. 
One terminal of the drive motor 20 is connected to the movable contact 56 
and the other terminal of the drive motor 20 is connected to the movable 
contact 64. The stationary terminal 52 of the relay 32 and the stationary 
terminal 62 of the relay 34 are connected to the positive terminal of a 
battery 66. In addition, the front limit switch 28 is connected to the 
emitter electrode of the transistor 42 via the relay coil 58 of the relay 
34 and to emitter electrode of the transistor 44. The front limit switch 
28 is also connected to the base electrode of the transistor 44 via the 
resistor r.sub.1. The base electrode thereof is connected to the anode of 
the diode 48 via the resistor r.sub.2. The collector electrode of the 
transistor 44 is connected to the base electrode of the transistor 42 via 
the resistor r.sub.3. The collector electrode of the transistor 42 is 
connected to the stationary terminal 52 of the relay 32 and the base 
electrode thereof is also connected to the stationary terminal 52 via the 
resistor r.sub.4. The rear limit switch 30 is connected to the emitter 
electrode of the transistor 40 and to the base electrode thereof via the 
resistor r.sub.5. The base electrode thereof is connected to the anode of 
the diode 46 via the resistor r.sub.6. The collector electrode of the 
transistor 40 is connected to the base electrode of the transistor 38 via 
the resistor r.sub.5. The rear limit switch 30 is also connected to the 
emitter electrode of the transistor 38 via the relay coil 50. The 
collector electrode of the transistor 38 is connected to the stationary 
terminal 52 of the relay 32 and to the battery 66. The base electrode of 
the transistor 38 is also connected to the stationary terminal 52 and the 
battery via the resistor r.sub.6. In addition, the relay 36 comprises an 
relay coil 68, stationary terminals 70 and 72 and a movable contact 74 
which can move between the stationary terminals 70 and 72 by means of the 
relay coil 68. The door switch 26, which becomes, respectively, ON and OFF 
when the door is opened and closed, is connected to the battery 66 via the 
relay coil 68 of the relay 36. The stationary terminal 70 is connected to 
the base electrode of the transistor 44 via the resistor r.sub.2 and to 
the anode of the diode 48. The stationary terminal 72 is connected to the 
base electrode of the transistor 40 via the resistor r.sub.6 and to the 
anode of the diode 46. The movable contact 72 is connected to the battery 
66. 
According to the first preferred embodiment of a seat belt system of the 
invention, the system includes an active belt switch 76 and an prohibition 
circuit 78. The active belt switch 76 becomes OFF when the manually, 
operated seat belt, which restricts the waist of the occupant, is set and 
it becomes ON when the seat belt is removed. The prohibition circuit 78 
becomes ON to inhibit the actuating of the control circuit 24 when the 
vehicle is rapidly decelerated, such as upon collision of the vehicle. The 
prohibition circuit 78 comprises a vehicle collision detecting switch 80, 
a short circuit 82 and pins 84, 86, 88 and 90 which form a 4-pin 
connector. The detecting switch 80 is connected to the pins 84 and 86. The 
short circuit 82 is connected to the pins 88 and 90 so as to be opposite 
to the detecting switch 80. In this prohibition circuit 78, the short 
circuit can not actuate when the connection between the pins 84 and 86 and 
the detecting switch 80 is not assured. The pin 84 is also connected to 
the cathode of the diode 48 and the pin 86 is also connected to ground. 
The pin 88 is also connected to ground via the active belt switch 76. In 
addition, the pin 90 is connected to the base electrode of a transistor 
92, the emitter electrode of which is connected to ground, by means of a 
timer circuit 94 which causes the transistor 92 to be ON during a 
predetermined time when the active belt switch 76 is ON. The collector 
electrode of the transistor 92 is connected to a warning lamp 96 and a 
chime 98 which are disposed in parallel. When the timer circuit 94 is 
actuated, the warning lamp 96 emits a light and the chime 98 produces a 
warning noise. The warning lamp 96 and the chime 98 are also connected to 
the battery 66 via an ignition switch 100. 
The operation of the seat belt system, according to the invention, is 
described below. 
When the door is opened, the door switch 26 becomes ON to actuate the relay 
36, so that the movable contact 74 of the relay 36 is in communication 
with the stationary terminal 70 thereof. As a result, electrical power is 
supplied to the the transistor 44. In addition,the front limit switch 28 
is ON when the sliding block 14 is not disposed at the front end of the 
guide rail 12. Therefore, the transistors 42 and 44 turn ON, so that 
electrical current runs through the relay coil 58, thereby the movable 
contact 64 of the relay 34 is in communication with the stationary 
terminal 62 thereof. As a result, electrical power is supplied to the 
drive motor 20 in the direction of the arrow A, so that the sliding block 
14 moves forward. Thereafter, when the sliding block 14 arriving at the 
front end of the guide rail 12 is detected, the front limit switch 28 
becomes OFF, so that power is not supplied to the drive motor 20. 
On the other hand, when the door is closed, the door switch 26 becomes OFF, 
so that the relay 36 becomes OFF, i.e. the movable contact 74 is in 
communication with the stationary terminal 72. In this case, power is 
supplied to the base electrode of the transistor 40 through the relay 36. 
In addition, the rear limit switch 30 is ON when the sliding block 14 is 
not disposed at the rear end of the guide rail 12. Therefore, the 
transistors 38 and 40 turns ON, so that the relay 32 becomes ON, i.e. the 
movable contact 56 is in communication with the stationary terminal 52. As 
a result, power is supplied to the drive motor 20 through the relay 32 in 
the direction of the arrow B, so that the sliding block 14 moves 
rearwardly. Thereafter, when the sliding block 14 arriving at the rear end 
of the guide rail 12 is detected, the rear limit switch 30 becomes OFF. As 
a result, power is not supplied to the drive motor 20, so that the 
movement of the sliding block 14 is stopped. 
When the vehicle is rapidly decelerated, such a upon collision of the 
vehicle, the detecting switch 80 turns ON. In this case, the electrical 
potentials of the bases of the transistors 40 and 44 are same as ground. 
Therefore, in cases where the door switch 26 turns ON because the door is 
broken in a car crash or the like, power is not supplied to the drive 
motor 20. As a result, the sliding block 14 is not moved, so that it is 
possible to restrain the occupant from thrown out of the vehicle. 
According to the first preferred embodiment of a seat belt system of the 
invention, when the active belt disposed about the waist of the occupant 
is removed, the active belt switch 76 turns ON to actuate the timer 
circuit 94. When the timer circuit 94 is actuated, power is supplied to 
the base electrode of the transistor 92, so that the transistor 92 turns 
ON, thereby the warning lamp 96 and the chime 98 is actuated for a 
predetermined time. In this case, the short circuit 82 is not actuated 
when the connections between the connectors 84 and 86 and the detecting 
switch 80 and/or between the connectors 88 and 90 and the short circuit 82 
are abnormal. When the short circuit 82 is not actuated, the warning lamp 
96 and the chime 98 are not actuated even if the manually operated belt is 
removed. Therefore, it is possible to confirm the non-connection state in 
the prohibition circuit 78. 
FIG. 3 shows the second preferred embodiment of a seat belt system, 
according to the present invention. As shown in FIG. 3, the short circuit 
82 is provided between the door switch 26 and the relay coil 68 of the 
relay 36. In this case, since the short circuit 82 is not actuated when 
the connections between the connectors 84 and 86 and the detecting switch 
80 and/or between the connectors 88 and 90 and the short circuit are 
abnormal, the control circuit 24 is not actuated when the door is opened 
and closed, so that the sliding block 14 does not move. Therefore, it is 
possible to judge whether or not the connection between the connectors in 
the prohibition circuit 80 exists.