JPH1134799A - Car body acceleration sensor for seat belt - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a car body acceleration sensor for a seat belt wherein a contact condition of a sensor case and an inertial unit can be properly maintained over a long period, also as a car body acceleration sensor total unit, compactness can be attained. SOLUTION: A sensor case 30 having an inertial unit support surface 30b relatively moving an inertial unit 33, when a speed change of the prescribed or more is received, is formed of only metal material, also the inertial unit 33 is a standing weight displaying behavior brought down on the inertial unit support surface 30b when a prescribed speed change is received, to be provided with a resin-made lower part 40 into contact with the inertial unit support surface 30b and a semi-spherical metal-made upper part 41 serving as an operating part of a sensor arm 30 in an upper part of the lower part 40.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle body acceleration sensor for a seatbelt, and more particularly to a seatbelt retractor mounted in a seatback of a reclining type seat of a vehicle or the like to prevent extension of a webbing in an emergency. The present invention relates to an improvement in a vehicle acceleration sensor for a seat belt that operates a locking means.

[0002]

2. Description of the Related Art Conventionally, retractors for a seat belt device for holding a vehicle occupant or the like safely in a seat include an automatic locking retractor and an emergency locking retractor. In order to solve the problem of excessive restraint and giving the wearer a feeling of pressure, sudden acceleration,
An emergency lock retractor has been used that has an emergency lock mechanism that physically locks the retractor by inertia sensing means that responds to a collision or deceleration, effectively and safely restrains the occupant, and reduces the feeling of pressure due to webbing. I have.

Further, as an inertial sensing means used in such an emergency lock type retractor, there is a vehicle body acceleration sensor for detecting vehicle body acceleration. For example, when the inertial body moves due to collision or inclination of the vehicle body, the vehicle body acceleration sensor swings an arm provided above the inertial body, and locks the rotation of the winding shaft on which the webbing is wound in the webbing withdrawing direction. It is the structure which operates the lock means which performs.

On the other hand, a retractor as described above is mounted in a seat back (seat back) of a reclining type seat of a vehicle or the like, and a vehicle acceleration sensor for a seat belt which can be operated similarly even when the inclination of the seat back is changed is provided. A seat belt device provided is disclosed in Japanese Patent Application Laid-Open No. 8-80807. Such a vehicle acceleration sensor for a seatbelt is supported on a first inertial member (inertial body) movably supported on a second inertial member (sensor case), and supported on a second inertial member. A sensor lever (sensor arm) that is swung by one inertial member. The second inertia member is supported on the retractor base so as to be pivotable about an axis extending parallel to the adjustment axis of the seatback on which the retractor is mounted. Further, the first inertia member prevents the winding shaft from rotating in the webbing pull-out direction by moving the sensor lever to engage the auxiliary teeth with the ratchet rotatable about the first axis. I do.

When the angle of the seat back is adjusted to different tilt positions, the retractor body attached to the seat back also has a different tilt direction, but the second inertia member is pivotally supported. Therefore, the first and second inertia members can always stay in the vertical direction.
Then, at the time of rapid deceleration such as at the time of a vehicle collision, the first inertia member vertically above the center of gravity of the second inertia member pivotably supported moves faster than the second inertia member. One inertia member can engage the auxiliary pawl with the ratchet via the sensor lever. As a result, the winding shaft is prevented from rotating in the webbing pull-out direction, and the occupant is restrained.

In the above-described vehicle acceleration sensor for a seatbelt, if the contact between the first inertial member and the second inertial member is a contact between metal surfaces, the contact surface between the first and second inertial members is long after long-term use. There is a possibility that the gap may be rusted, and a change in frictional force between the contact surfaces may cause a problem such as a decrease in sensor sensitivity. Further, in order to prevent the second inertial member from being accidentally moved by the acceleration of the vehicle, it is necessary to take measures such as increasing the inertial mass of the second inertial member.

Therefore, in the case of the above-mentioned Japanese Patent Application Laid-Open No. 8-80807, a metal spherical body is used for the inertia member as the first inertia member, and the above-mentioned sensor case as the second inertia member is used for the sensor case. It has an inertial body support surface for supporting the inertial body and is composed of a resin upper part pivotally supported by the retractor base and a metal weight mounted below the upper part.

[0008]

However, in the above-described structure of the sensor case, when an excessive impact acts on the sensor case at the time of a vehicle collision, a resin upper portion and a metal weight assembled thereunder are provided. A tensile load is applied to the joint with the part. Therefore, in consideration of impact resistance, the upper part made of resin in the sensor case must be increased in thickness to increase strength, and as a result, the volume of the entire sensor case increases, There has been a problem that the size of the vehicle acceleration sensor is increased.

Accordingly, an object of the present invention is to solve the above-mentioned problems, and it is possible to maintain the contact state between the sensor case and the inertial body properly for a long period of time, and to reduce the overall size of the vehicle body acceleration sensor. It is an object of the present invention to provide a vehicle acceleration sensor for a seat belt which can be achieved.

[0010]

SUMMARY OF THE INVENTION The object of the present invention is to provide a first mechanism for operating a locking means for locking the rotation of a winding shaft of a retractor for a seat belt in a webbing withdrawing direction.
And a sensor arm rotatably mounted on the retractor base to be located at a position of the vehicle and a second position at which the locking means is not operated, respectively, and parallel to an adjustment axis of a seat back of a reclining type seat of a vehicle or the like. A sensor case rotatably supported by the retractor base around a rotation axis extending to the sensor case, and, when receiving a speed change of a predetermined value or more, the sensor case relatively moves on an inertial body supporting surface of the sensor case, and An inertial body for moving an arm to the first position, wherein a vehicle body acceleration sensor for a seat belt for operating the locking means by a movement operation of the inertial body when a predetermined vehicle body acceleration is applied,
The sensor case is formed only of metal,
The inertial body is a standing weight that exhibits a behavior of falling on the inertial body support surface of the sensor case when a predetermined vehicle acceleration is applied, and a lower portion made of resin that contacts the inertial body support surface; This is achieved by a vehicle body acceleration sensor for a seatbelt, which has a structure including a metal upper portion serving as an operation portion of the sensor arm above the portion.

According to the above structure, the inertial body is a standing weight that exhibits a behavior of falling on the inertial body support surface of the sensor case when a predetermined vehicle acceleration is applied, and the inertial body is supported by the inertial body support surface of the sensor case. Because the lower part that contacts the sensor case is made of resin, the contact between the sensor case and the inertial body does not become the contact between the metal surfaces. For this reason, it is possible to prevent the generation of vibration noise due to the contact between the metal parts when the vehicle is running and when the sensor is operating. In addition, since the sensor case is formed only of metal, it is easy to secure mechanical strength and impact resistance even when the thickness is reduced, and the volume of the sensor case is reduced by thinning, etc., and the overall body acceleration sensor is compact. Can be achieved.

[0012]

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a vehicle body acceleration sensor for a seat belt according to an embodiment of the present invention. 1 to 6 show an embodiment of a vehicle body acceleration sensor for a seat belt according to the present invention. FIG. 1 shows a retractor for a seat belt provided with a vehicle body acceleration sensor 32 according to an embodiment of the present invention. FIG. 2 is a front longitudinal sectional view of a main part of the seat belt retractor 100 shown in FIG. 1, FIG. 3 is an exploded perspective view of the seat belt vehicle body acceleration sensor 32 shown in FIG. FIG. 4 is an enlarged perspective view of the sensor case shown in FIG.

The seat belt retractor 100 equipped with the vehicle body acceleration sensor 32 of the present embodiment is attached to a seat back (seat back) of a reclining type seat of a vehicle or the like. The seat back is connected to a bottom cushion of the seat so as to be pivotable about an adjustment axis extending in the width direction of the vehicle body, and the tilt state is adjusted according to the physique and the like of the occupant.

The seat belt retractor 100
As shown in FIGS. 1 and 2, a substantially cylindrical bobbin 2 around which a webbing 70 is wound, a bobbin 2 inserted through the bobbin 2 and rotatably supported by a retractor base 1. A take-up shaft 4 provided with a certain latch plate 4a on one end side (right side in FIG. 2);
and an emergency lock mechanism 300 for preventing rotation of the webbing in direction a. The webbing 70 extending from the retractor 100 attached to a seat back (not shown) restrains the occupant to the seat.

The retractor base 1 fixed to a frame member (not shown) of the seat back is formed by press-molding a metal plate so that most of the retractor base 1 has a U-shaped cross section. At a position facing the side plate 1a, a winding shaft 4 combined with the bobbin 2 is rotatably bridged. A known take-up spring device that constantly urges the bobbin 2 in the webbing take-up direction through the take-up shaft 4 is provided at the other end of the take-up shaft 4 through which the side plate 1a of the retractor base 1 is inserted. (Not shown).

In the present invention, various known structures can be adopted as the specific structure of the emergency lock mechanism 300 for restraining the take-up shaft 4 from rotating in the webbing withdrawing direction in the event of a vehicle emergency. For example, in the case of the present embodiment, the ratchet wheel 19 serving as the lock operating means causes a rotation delay with respect to the take-up shaft 4, so that the latch cup 13
Engages the pawl 11 serving as the locking means with the latch plate 4a, and prevents the winding shaft 4 from rotating in the webbing pull-out direction.

Further, below the ratchet wheel 19, a tooth 19 which is an engaging portion of the ratchet wheel 19 is provided.
The sensor case 30 which forms the vehicle body acceleration sensor 32 of the present invention together with the sensor arm 31 engageable with a
It is disposed rotatably with respect to the retractor base 1 via a hanger 38. The "lock means" in the present invention means the emergency lock mechanism excluding the vehicle body acceleration sensor 32.

The vehicle body acceleration sensor 32 is provided so that the side plate of the retractor base 1 is located at a first position engaging with the teeth 19a of the ratchet wheel 19 and a second position not engaging with the teeth 19a. A sensor arm 31 attached to the sensor case 1a, and an inertial body 3 for relatively moving on the sensor case when receiving a speed change of not less than a predetermined value and moving the sensor arm 31 to the first position.
3 is provided.

The sensor arm 31 has a base shaft 31a pivotally supported by an arm support 35 provided on a hanger 38, and is rotatably supported by the side plate 1a of the retractor base 1 via the hanger 38. Is attached,
The ratchet wheel 19 is swingably displaceable from a second position (position shown in FIG. 1) not engaging with the teeth 19a to a first position (position shown in FIG. 6) engaging with the teeth 19a. That is, the sensor arm 31 latches the pawl 11 via the latch cup 13 by engaging the teeth 19a of the ratchet wheel 19 to cause a rotation delay of the ratchet wheel 19 with respect to the winding shaft 4. By engaging with the plate 4a, the rotation of the winding shaft 4 in the webbing withdrawing direction is prevented.

The sensor case 30 is integrally formed of a metal material in a cylindrical shape with a bottom, and as shown in FIG. 4, a flat inertial body support surface 3 on which the inertial body 33 is placed.
0b is provided on the inner bottom, and support holes 30a, 30a into which the case support protrusions 36 of the hanger 38 are rotatably fitted are provided at positions facing the upper edge of the peripheral wall.

The case support projection 36 of the hanger 38
Is a pivot that extends parallel to the adjustment axis of the seat back of the reclining seat of the vehicle or the like when attached to the retractor base 1. Accordingly, when the sensor case 30 is attached to the retractor base 1 via the hanger 38, the sensor case 30 is rotatable about a rotation axis S extending parallel to the adjustment axis of the seat back. It is supported by the retractor base 1.

The bottom of the sensor case 30 is set to have a large thickness so that the sensor case 30 does not inadvertently swing due to a change in the speed of the vehicle, and a function as a weight for increasing the inertial mass is obtained. ing. Further, in the case of the present embodiment, at the center of the inertial body support surface 30b,
A hole 30c into which a protrusion 33a protruding from the center of the bottom of the inertial body 33 is loosely formed is formed therethrough. The edge of the hole 30c opening to the inertial body support surface 30b is chamfered 30d so that when the inertial body 33 falls down, it does not interfere with the root outer periphery of the projection 33a.

The inertial body 33 is provided on the inertial body support surface 30.
When the sensor arm 31 is placed on the sensor b and receives a speed change equal to or more than a predetermined value, the sensor arm 31 relatively moves on the inertial body support surface 30b and moves the sensor arm 31 to the first position. Further, the inertial body 33 is a substantially cylindrical standing weight that exhibits a behavior of falling on the inertial body support surface 30b of the sensor case 30 when a predetermined vehicle acceleration is applied. It has a structure having a lower portion 40 made of resin that contacts the support surface 30b and an upper portion 41 made of a hemispherical metal located above the lower portion 40 and serving as an operating portion of the sensor arm 31. , The inertial body 33
Is set so that the portion that comes into contact with the inner wall of the sensor case becomes the lower portion 40 made of resin when the device falls down due to a speed change of a predetermined value or more.

At the center of the lower end surface of the lower portion 40, there is provided a projection 33a which fits loosely into a hole 30c passing through the inertial body support surface 30b. The outer diameter of the projection 33a is set appropriately smaller than the inner diameter of the hole 30c. In FIG. 4, a hatched ring-shaped area f indicates a contact area when the inertial body 33 is set on the inertial body support surface 30b. The inertial body 33 set on the inertial body supporting surface 30b is
1 is attached to the inertial body receiving portion 31 of the sensor arm 31.
The position of the sensor arm 31 is regulated by bringing the sensor arm 31 into contact with c.

When the inertia body 33 is set on the inertia body support surface 30b, the center of the hemisphere of the upper portion 41 is located on the rotation axis S of the sensor case 30. The dimensions of each part are set such that the center of gravity is located on a vertical line passing through the 30 rotation axes S. Therefore, the positional relationship between the sensor arm 31 and the ratchet wheel 19 does not change even if the seat back reclines and the retractor 100 is tilted.

Therefore, the inertial body 33 maintains an upright posture on the inertial body support surface 30b when the acting speed change is equal to or less than a predetermined value.
In the second position. On the other hand, the inertial body 33
Shows a behavior of falling on the inertial body support surface 30b when the acting speed change becomes equal to or more than a predetermined value. By this behavior, the sensor arm 31 is pushed up and the sensor arm 31 is held at the first position.

Therefore, the vehicle body acceleration sensor 32 is
As shown in FIG. 5, even if the retractor base 1 is tilted in the direction of the arrow (a) in FIG. 5 with the reclining of the seat back, the sensor case 30 is rotated in the direction of gravity by the weight at the bottom, and is always kept. It is kept at a constant ground angle.
Then, the inertial body 33 does not move relative to the sensor case 30, and the sensor arm 31 remains at the second position, which is the normal position.

When the vehicle acceleration is applied to the seat belt retractor 100 in the event of a vehicle emergency such as a collision, and the vehicle speed sensor 32 for the seat belt receives a speed change of a predetermined value or more, as shown in FIG. The inertia force F causes the body 33 to fall in the direction of the inertia force, and pushes up the sensor arm 31, so that the sensor arm 31 is positioned at the first position.

That is, the vehicle acceleration sensor 3 of the present embodiment
2, when the inertial body 33 is subjected to a predetermined vehicle acceleration, the inertial body supporting surface 30 of the sensor case 30
Since the lower portion 40 that contacts the inertial body support surface 30b of the sensor case 30 is made of a resin, the contact between the metal sensor case 30 and the inertial body 33 is made between the metal surfaces. Contact. For this reason, it is possible to prevent the generation of vibration noise due to the contact between the metal parts when the vehicle is running and when the sensor is operating.

Therefore, even when used for a long time, the contact surfaces do not rust, and the fluctuation of the frictional force between the contact surfaces can be prevented, so that good sensor sensitivity can be maintained for a long time. Becomes possible. Further, since the sensor case 30 is formed only of a metal material, it is easy to secure mechanical strength and impact resistance even if the thickness is reduced, and the volume of the sensor case 30 is reduced by reducing the thickness. The overall size can be reduced. Since a tensile load is not applied to the joint between the lower part 40 and the upper part 41 of the inertial body 33 at the time of a vehicle collision, the lower part 40 made of resin is increased in thickness to increase strength. There is no need and there is no increase in size.

When the inertia body 33 falls due to a speed change of a predetermined value or more, first, as shown in FIG.
The inertial body 33 slides on the inertial body supporting surface 30b in the direction of the inertial force F by the inertial force F due to the speed change, and moves to the protrusion 33a.
After one side surface of the lower case 40 abuts against the hole 30c of the sensor case 30, the lower portion 40 starts to fall with the lower peripheral edge 40a as a fulcrum.

At the start of the fall, if the opening edge of the hole 30c in which the projection 33a is loosely fitted is not chamfered 30d, the corner of the opening edge interferes with the root of the projection 33a. Since the frictional force of the contact portion between the sensor case 30 and the inertia body 33 increases, the inertia body 33 is less likely to fall down, which may cause inconveniences such as a decrease in sensor sensitivity. The opening edge of the hole 30c is chamfered 30d, and the corner of the opening edge is the protrusion 3d.
There is no interference with the root of 3a. Therefore, the frictional force at the contact portion between the sensor case 30 and the inertial body 33 can be reduced, and the drop in sensor sensitivity can be suppressed.

As shown in FIG. 8, the inertial body support surface 30b of the sensor case 30 has
0b, and crosses a ring-shaped area f with which the inertia body 33 contacts along a direction in which an inertial force acts due to a change in the speed of the vehicle (a direction orthogonal to the rotation axis S of the sensor case 30). A concave groove 44 may be provided. By providing such a concave groove 44, the inertia body 33 is more likely to fall in the extending direction of the groove than in other directions.
The sensitivity of the inertial body 33 can be changed depending on the direction in which the inertia force acts, or the sensitivity of the inertial body 33 can be varied depending on the direction in which the inertial force acts. Of course, the cross-sectional shape of the concave groove 44 is
It is not limited to the illustrated example.

The configurations of the locking means, the sensor arm, the sensor case, and the inertial body in the present invention are not limited to the configurations of the above-described embodiment, but can be appropriately changed based on the gist of the present invention. Needless to say.

[0035]

According to the vehicle body acceleration sensor for a seatbelt of the present invention, the inertial body is a standing weight that exhibits a behavior of falling on the inertial body supporting surface of the sensor case when a predetermined vehicle body acceleration acts. Because the lower part that contacts the inertial body support surface of the sensor case is made of resin,
The contact between the sensor case and the inertial body is not the contact between metal surfaces. Therefore, it is possible to prevent the generation of vibration noise due to the contact between the metal parts when the vehicle is running and when the sensor is operating.

In addition, even during long-term use, the contact surfaces do not rust, and fluctuations in the frictional force between the contact surfaces can be prevented, so that good sensor sensitivity is maintained for a long period of time. Becomes possible. In addition, since the sensor case is formed only of metal material, it is easy to secure mechanical strength and impact resistance even if the thickness is reduced, and the volume of the sensor case is reduced by thinning etc. Can be achieved.

[Brief description of the drawings]

FIG. 1 is a side view of a main part of a seat belt retractor provided with a vehicle body acceleration sensor according to an embodiment of the present invention.

FIG. 2 is a front vertical sectional view of a main part of the seat belt retractor shown in FIG.

FIG. 3 is an exploded perspective view of the vehicle body acceleration sensor for the seat belt shown in FIG. 1;

FIG. 4 is an enlarged perspective view of the sensor case shown in FIG.

FIG. 5 is a side view of a main part of the vehicle body acceleration sensor in a state where the inclination of the seat back to which the seat belt retractor shown in FIG. 1 is attached is changed.

FIG. 6 is a side view of a relevant part showing an operation of the vehicle body acceleration sensor when acceleration equal to or more than a predetermined value acts in the posture shown in FIG.

FIG. 7 is a cross-sectional view showing the relationship between the structure of the inertial body support surface of the sensor case and the behavior of the inertial body on the inertial body support surface when a predetermined acceleration is applied.

FIG. 8 is a perspective view showing another embodiment of the sensor case according to the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Retractor base 2 Bobbin 4 Take-up shaft 19 Ratchet wheel 11 Pole 30 Sensor case 31 Sensor arm 32 Vehicle acceleration sensor for seat belt 33 Inertial body 38 Hanger 40 Lower part 41 Upper part 70 Webbing 100 Retractor for seat belt

Claims (1)

[Claims] 1. A seat belt retractor which is located at a first position for activating a locking means for locking rotation of a winding shaft of a retractor for a webbing in a webbing withdrawing direction and a second position for not operating the locking means. A sensor arm rotatably attached to the retractor base and a pivotal axis extending parallel to an adjustment axis of a seat back of a reclining type seat of a vehicle or the like so as to be rotatable around the retractable base. A predetermined vehicle body comprising: a supported sensor case; and an inertial body that, when subjected to a speed change of not less than a predetermined value, relatively moves on an inertial body supporting surface of the sensor case and moves the sensor arm to the first position. A vehicle body acceleration sensor for a seat belt that operates the locking means by a movement operation of the inertial body when acceleration is applied, The sensor case is formed of only a metal material, and the inertial body is a standing weight that exhibits a behavior of falling on an inertial body supporting surface of the sensor case when a predetermined vehicle acceleration is applied. A vehicle body acceleration sensor for a seat belt, comprising: a lower portion made of a resin that comes into contact with a support surface; and an upper portion made of metal serving as an operation portion of the sensor arm above the lower portion. .