JPH08216832A - Acceleration sensor - Google Patents

Abstract

PURPOSE: To provide an acceleration sensor to shorten the time until an emergency locking mechanism of a retractor is actuated and to actuate the emergency locking mechanism capable of reducing an extending amount of a webbing. CONSTITUTION: A bearing surface of a sensor case 13 is furnished with an inside conical surface 131 and an outside conical surface 132, and inclination against a horizontal surface on a section of the inside conical surface 131 is formed smaller than the outside conical surface.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an acceleration sensor,
In particular, the present invention relates to an acceleration sensor for starting an emergency lock device attached to a retractor (winding device) for a seat belt of an automobile.

[0002]

2. Description of the Related Art Conventionally, a seat belt for safely holding an occupant or the like of a vehicle on a seat is composed of a webbing, a buckle, a mounting device and a retractor. The retractor is a device that automatically retracts the webbing when the seatbelt is not used, and is a winding device that prevents damage to the webbing and allows the length of the webbing to be freely changed when the seatbelt is used. Such retractors include self-locking type retractors and emergency locking type retractors, but in general, in order to solve the problem of restraining the occupant excessively and giving the wearer a feeling of pressure, sudden acceleration, Equipped with an emergency lock mechanism that responds to a collision, rear-end collision or deceleration,
Emergency lock retractors have been used to effectively and safely restrain occupants.

As shown in FIGS. 1 and 2, conventionally, an acceleration sensor 1 for starting an emergency locking device attached to such an emergency locking retractor 100 has a concave body 3a for receiving a ball weight 2. It is composed of a case 3 and a sensor arm 5 having a cap 4 rotatably attached to the sensor case 3 and abutting against the ball weight 2.

When the vehicle receives an acceleration of a predetermined value or more in an emergency, the ball weight 2 of the emergency lock mechanism has a concave body 3a.
Since the sensor arm 5 is moved upward to swing and the tip 5a of the sensor arm is engaged with the teeth 6a of the ratchet wheel 6 forming a part of the emergency lock mechanism, rotation of the ratchet wheel 6 in the belt withdrawing direction is prevented. It And
If the webbing is further withdrawn while the ratchet wheel 6 is prevented from rotating, the ratchet wheel 6 is delayed in rotation with respect to the rotation of the unillustrated winding shaft in the webbing withdrawing direction, so that the emergency locking mechanism operates. The webbing drawer is locked.

The concave body 3a of the sensor case 3 of the conventional acceleration sensor has a conical shape whose cross section is inclined with respect to the horizontal plane. The inclination angle of the conical shape is determined by the acceleration set by the acceleration sensor 1. For example, in the case of a normal passenger car, this inclination angle is set to about 20 ° and the emergency lock mechanism is activated when an acceleration of about 0.7 G (Note: G is 9.8 m / sec ² ) or more is received. Is set to.

As shown in FIG. 3 which shows the relationship between acceleration and time, in the case of a vehicle with a hard suspension such as a truck, the set value G2 of the acceleration sensor for activating the emergency lock mechanism attached to the retractor is set as a value for a normal passenger vehicle. It is set higher than the set value G1 of the acceleration sensor used for.
This is because, in a vehicle with a hard suspension such as a truck, vibration with a considerably high acceleration is input to the retractor even during normal driving, so setting the acceleration setting value that activates the emergency lock mechanism to the level of passenger cars This is because the emergency lock operation is performed even with the small unevenness of the upper body, and the upper body is still pressed down by the belt. For example, in the case of a car with a hard suspension such as a truck, the inclination angle should be set to about 50 ° and 1.5G (Note:
G is set so that the emergency lock mechanism is activated when an acceleration of 9.8 m / sec 2) or more is received.

[0007]

However, as shown in FIG. 2, when the inclination angle of the concave body 3a of the sensor case 3 used in the conventional emergency lock mechanism is constant, the acceleration of the weight ball 2 becomes a set value. I will move after crossing,
It takes a time (T1) until the sensor arm 5 and the ratchet wheel 6 forming a part of the emergency lock mechanism engage with each other to start the emergency lock mechanism, and the webbing extends during this time to impair the restraint of the occupant. In a vehicle such as a truck having a high acceleration set value (G2), the time (T2) from the collision until the acceleration reaches the set value becomes long, which is a significant problem. (Fig. 3)

Further, in order to prevent the tip of the sensor arm from swinging due to vertical acceleration due to the unevenness of the road or the like to be locked with the ratchet wheel, there is a tolerance of machining / forming accuracy between the tip of the sensor arm and the ratchet wheel. It is necessary to provide sufficient clearance in consideration of play between parts. In order to mesh with the ratchet wheel 6, the sensor arm 5
It is necessary to move within this clearance, and the webbing extends within this moving time, and the restraint of the occupant becomes poor.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to solve the above problems, and to shorten the time until the emergency lock mechanism of the retractor is activated and to reduce the amount of extension of the webbing, the acceleration sensor for operating the emergency lock mechanism. To provide.

[0010]

SUMMARY OF THE INVENTION The above object of the present invention is a sensor case for actuating an emergency locking mechanism for preventing extension of a webbing in an emergency, and a sensor case swingably pivotally attached to the sensor case. In an acceleration sensor having a sensor arm and a ball weight that is placed in the sensor case and moves when it receives an acceleration of a predetermined value or more and swings the sensor arm, the seat surface of the sensor case in which the ball weight moves. Is provided with an inner conical surface and an outer conical surface having an inclination angle with respect to a horizontal plane larger than the inner conical surface.

[0011]

According to the above configuration of the present invention, the seat surface of the sensor case on which the ball weight moves comprises an inner conical surface and an outer conical surface having an inclination angle with respect to a horizontal plane larger than the inner conical surface. When the ball weight is in contact with the inner conical surface and the outer conical surface at the same time, the swing end of the sensor arm is configured to be close to the emergency lock mechanism. Even when the acceleration is high, the ball weight moves on the inner conical surface and contacts the outer conical surface with an acceleration smaller than the set acceleration in an emergency, and the sensor arm is swung to some extent in advance to form a part of the emergency lock mechanism. The tip can be kept close to the ratchet wheel. After this, when the acceleration further rises and reaches the set acceleration, the tip of the arm and the ratchet wheel are already close to each other, so the sensor arm locks the ratchet wheel by a slight movement of the ball weight on the outer conical surface, causing an emergency. The locking mechanism can be activated.

An embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

[0013]

FIG. 4 is a sectional view showing a normal state of an acceleration sensor according to an embodiment of the present invention. FIG. 5 is a cross-sectional view showing a state in which the acceleration sensor of the above embodiment receives an acceleration smaller than the set acceleration, and the ball weight is in contact with both the inner conical surface and the outer conical surface. FIG. 6 is a cross-sectional view showing a state immediately before the weight ball abuts only on the outer conical surface after the acceleration set by the acceleration sensor of the above-described embodiment is exceeded and the sensor arm and the ratchet wheel mesh with each other. FIG. 7 is a cross-sectional view showing a state in which acceleration exceeding a set acceleration is applied to the acceleration sensor of the above-described embodiment and the sensor arm and the ratchet wheel mesh with each other.

As shown in FIG. 4, the acceleration sensor 11 in the above-described embodiment has a sensor case 13 having a concave body 13a for receiving the ball weight 12, and a rotatably pivotally attached to the sensor case 13 and attached to the ball weight 12. The sensor arm 15 is in contact with the sensor arm 15. The sensor case 13 is formed of plastics having a relatively small elastic coefficient in order to reduce the contact sound with the weight ball 12 due to vibration. The ball weight 12 is preferably made of a metal or a resin having a high specific gravity, and the surface of the ball weight 12 is preferably plated with Cr, which has good slidability, and solid lubricant treatment.

The seat surface of the concave body 13a of the sensor case 13 on which the ball weight 12 moves is composed of an inner conical surface 131 and an outer conical surface 132, and the sensor case 13 is located at the center of the inner conical surface 131. A hole 133 is provided for treating dust that has entered the inside. Inclination angle α with respect to the horizontal plane in the cross section of the inner conical surface 131
Is set to be smaller than the inclination angle β with respect to the horizontal plane in the cross section of the outer conical surface 132, and as shown in FIG.
Only 31 is contacted.

As shown in FIG. 4, when the acceleration sensor 11 is in the normal position, there is sufficient clearance between the tip 15a of the sensor arm 15 and the ratchet wheel 16 which forms a part of the emergency lock mechanism. It prevents the webbing from being locked unnecessarily due to backlash, precision of parts, and vertical acceleration due to unevenness of the road.

If front and rear and left and right accelerations are applied to the vehicle at the time of an emergency such as an accident, the acceleration of the retractor or the acceleration sensor gradually rises due to the characteristics of the vehicle, and the acceleration sensor 11 becomes A weak acceleration is applied at the beginning. As shown in FIG. 5, the acceleration sensor 11
Is the inner conical surface 1 with which the ball weight 12 normally contacts.
Since the inclination angle of 31 is gentler than the outer conical surface 132, the ball weight 12 starts to move with a weak acceleration,
It collides with the outer conical surface 132 having a larger inclination angle and stops. At this time, the ball weight 12 contacts both the inner conical surface 131 and the outer conical surface 132, and the clearance between the tip 15a of the sensor arm 15 moved by the ball weight 12 and the ratchet wheel 16 is as shown in FIG. The ball weight 12 of No. 4 is set to be smaller than that in the normal position.

As shown in FIGS. 6 to 7, when the acceleration further rises and exceeds the set value, the ball weight 12
Goes up the outer conical surface 132 having a large inclination angle and reaches the tip 15a of the sensor arm 15 and the ratchet wheel 16
Engage with and activate the webbing's emergency locking mechanism.

Here, the time until the tip 15a of the sensor arm 15 and the ratchet wheel 16 are engaged with each other to start the emergency lock mechanism, that is, the time required to shift from the state of FIG. 4 to the states of FIGS. 6 to 7. In contrast, the conventional inclination angle is shorter than that of the conventional one, and the amount of extension of the webbing during this is small, and the restraint of the occupant can be improved.

It is preferable to set the inclination angle α with respect to the horizontal plane in the cross section of the inner conical surface 131 to 30 ° to 35 ° and the inclination angle β of the outer conical surface 132 to 50 ° to 58 °. Further, it is more preferable to set the inclination angle α with respect to the horizontal plane in the cross section of the inner conical surface 131 to 32 ° and the inclination angle β of the outer conical surface 132 to 55 °.

Further, in this embodiment, the inner conical surface 1
A hole 133 for dust disposal is provided at the center of 31.
It is also possible to omit this hole 133.

[0022]

As described above, according to the present invention, even in the case where the acceleration set by the acceleration sensor is high, the ball weight moves on the inner conical surface and moves on the outer conical surface with an acceleration smaller than the set acceleration in an emergency. It is possible to bring the sensor arm into contact with the ratchet wheel and swing the sensor arm to some extent to bring the tip of the ratchet wheel, which is a part of the lock mechanism, close to the ratchet wheel. After this, when the acceleration further rises and reaches the set value acceleration, the arm tip and the ratchet wheel are already close to each other, so the sensor arm locks the ratchet wheel with a slight movement of the weight ball on the outer conical surface, The emergency lock mechanism is activated.

Therefore, even when the set acceleration is high like an acceleration sensor for operating an emergency lock mechanism attached to a retractor such as a truck, the time from the acceleration rise (the moment of collision) to the locking of the webbing can be shortened,
During this time, the amount of webbing elongation can be reduced and the restraint of the occupant can be improved.

Further, according to the present invention, the tip of the sensor arm is brought closer to the ratchet wheel in advance when an acceleration smaller than the set acceleration is applied. Therefore, the clearance between the tip of the sensor arm and the ratchet wheel at the initial position is widened. Can be taken. As a result, it is not necessary to increase the processing accuracy and molding accuracy of the parts, and it is possible to prevent erroneous locking due to weak acceleration or acceleration due to uneven roads.

[Brief description of drawings]

FIG. 1 is a schematic view of an emergency lock retractor 100 provided with an acceleration sensor 1 for starting a conventional emergency lock mechanism.

FIG. 2 is an enlarged perspective view of the conventional acceleration sensor 1 described above.

FIG. 3 is a diagram showing a relationship between acceleration and time.

FIG. 4 is a sectional view showing an initial state of the acceleration sensor according to the embodiment of the present invention.

FIG. 5 is a cross-sectional view showing a state in which an acceleration equal to or lower than a set acceleration is applied to the acceleration sensor of the above-described embodiment.

FIG. 6 is a cross-sectional view showing a state immediately before an acceleration exceeding a set acceleration is applied to the acceleration sensor of the above embodiment and the sensor arm and the ratchet wheel are meshed with each other.

FIG. 7 is a cross-sectional view showing a state in which acceleration exceeding a set acceleration is applied to the acceleration sensor of the above-described embodiment, and the sensor arm and the ratchet wheel mesh with each other.

[Explanation of symbols]

 1, 11 Acceleration sensor 2, 12 Ball weight 3, 13 Sensor case 13a Concave body 131 Inner conical surface 132 Outer conical surface 4 Cap 5, 15 Sensor arm 6, 16 Ratchet wheel

Claims (1)

[Claims] 1. A sensor case for actuating an emergency lock mechanism for preventing extension of the webbing in an emergency, a sensor arm pivotally mounted on the sensor case, and a sensor arm mounted in the sensor case. An acceleration sensor having a ball weight that moves and oscillates the sensor arm when subjected to a change in acceleration of a predetermined amount or more, wherein the seat surface of the sensor case on which the ball weight moves is an inner conical surface and an inner conical surface. An outer conical surface having an inclination angle with respect to a larger horizontal plane.