JPS6127711B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a vehicle body acceleration sensitive sensor for an emergency lock type retractor for a seat belt.

It is well known that seat belts are widely used to protect the safety of vehicle occupants. This seatbelt is normally wound and housed in a retractor called a retractor, pulled out when in use, and automatically retracted by a biasing spring when not in use. Emergency locking devices are generally installed to protect occupants from accidents.

The emergency locking device senses the acceleration of the vehicle body and uses the displacement to engage and lock the pawl on the ratchet wheel at the end of the reel around which the belt is wound. It utilizes the tensile inertia of the belt web when it is pulled out. There are two types of locking methods: one that locks the vehicle by locking the vehicle, and the other that uses a combination of both methods. Among these, the method that detects and locks the vehicle body acceleration senses changes in vehicle body acceleration and transmits this to the locking means. An acceleration sensor is installed.

In the past, various proposals have been made as such sensitive sensors and attempts have been made to put them into practical use, but the following are known as the most common ones. That is, one of them is a dish-shaped support 1 having an inclined support surface as shown in FIG. The actuator 3 is rotated by the displacement of the spherical inertial body 2 that rolls on an inclined surface due to changes in vehicle acceleration, and an emergency locking means (not shown) rotates the actuator 3. As shown in FIG. 2, the other is a support base 1' having a concave portion having an inverted trapezoidal cross section, and a cylindrical support leg that is inserted into the concave portion of the support base 1'. Or a truncated cone-shaped inertial body 2'
and an actuator 3' that contacts the upper part of the inertial body 2' and rotates in accordance with the displacement of the inertial body 2'.

In the former case, the part where the actuator 3 contacts the inertial body 2 is a spherical surface, so no force is generated on the pure frame to lift the actuator 3, and this force does not change the position of the inertial body ball. This is caused by a movement which attempts to bite into the member formed by the set angle defined by the angle of inclination of the support base 1 by means of a wedging action. Therefore, due to the rolling of the inertial body, the friction between the inertial body and the achiator greatly affects the operation. This results in insufficient responsiveness to changes in vehicle acceleration, resulting in variations in the time it takes to operate.

On the other hand, in the latter case, the inclination angle of the inertial body 2' is determined by the inclination angle of the recessed part of the support base 1', and the set angle is defined as the angle between the center axis of the inertial body and the line connecting the center of gravity of the inertial body and the periphery of the bottom surface of the inertial body. , when the inertial body is tilted, if the angle between the center axis of the inertial body at its maximum tilt and the vertical line is the inclination angle, then if the inclination angle exceeds the set angle even slightly, the inertial body will begin to incline, and exhibits an operation in which it stops when a set tilt angle is reached and does not return unless the tilt angle is raised;
The amount corresponding to the inclination angle directly becomes a hysteresis phenomenon, which appears as a drawback in that a large return force must be applied to the inertial body at the time of return. This is because the former is based on rolling, whereas the former uses tilting with a single point as a pivot.
This is a fatal flaw in this method.

Thus, it is an object of the present invention to provide a novel sensor that overcomes the various fulcrums of both sensors as described above.

That is, one of the objects of the present invention is that the dynamic characteristics are not easily affected by frictional force, and therefore the responsiveness is good.
An object of the present invention is to provide an improved sensor that exhibits little variation in time to activation.

Another object of the present invention is to make the actuator operate well in all directions with very little dynamic and static directionality, and to reduce the difference between the actuation start angle and the return start angle, the so-called hysteresis phenomenon. The object of the present invention is to provide a sensor that has little loss and has excellent returnability.

The configuration of the vehicle body acceleration sensitive sensor of the present invention that achieves the above object is clear from the claims, but its specific embodiments can be more fully understood from the drawings and the following description. It will be done.

FIG. 3 is an exploded perspective view showing one implementation row of the sensor according to the present invention, which is composed of an inertial body support 11, an inertial body 12, and an actuator 13, and supports the inertial body 12. The actuator 13 is held on a stand 11, and the actuator 13 is disposed in contact with the upper surface of the actuator 11, and the shaft insertion cylinder part 17 of the actuator 13 is interposed between the separate shaft insertion cylinders 14 of the support stand 11. By inserting the shaft pin 15 through 14 and 17, it is assembled as one piece.

Note that 18 is an arm that maintains the balance of the actuator 13, and is formed in relation to the actuator 13.

The configuration of such a sensor is a basic one as a sensor, and similar aspects can be found in the configurations of known sensors.

In such a configuration, the present invention provides the respective parts 11,
This is achieved by making the inertia body 12 have a relationship with each other, and in particular by giving the inertial body 12 a unique configuration.

The details will be explained below with reference to each embodiment shown in FIG. 3 and FIGS. 4 to 7.

First, one of them is the support stand 11.

As is clear from FIGS. 4 to 7, this support stand 11 has a through hole 16 penetrating to the bottom surface at the center of the support that supports the upper inertial body, and supports the inertial body in rolling motion. The surface 11a is formed into an upwardly inclined surface that gradually slopes upward from the through hole 16 in the radial direction. The upward inclination angle of the inclined support surface 11a is an important factor that defines the amount of displacement of the inertial body and the amount of displacement of the actuator, and determines the wedge angle that improves the returnability, which will be described later.

Next, the second is the inertial body 12 which has the most characteristic structure in the present invention, and its shape is a cylindrical body 12A with a spherical arc surface formed on the bottom surface as shown in FIG. The top surface of the sphere 12B is cut to form a flat surface 21, or the top surface of the sphere 12C is cut into a gentle V-shaped surface 22 as shown in FIG.
3, but at least the bottom side 12a in contact with the support base 11 is formed into a spherical arc surface centered on the center of gravity of the inertial body 12. There must be. This is an important element in imparting rolling motion to the inertial body 12. Moreover, the inertial body 12 in the present invention
Furthermore, the through hole 1 is located at the support center of the support base 11 at the center of the bottom surface 12a forming the spherical arc surface.
A tapered portion 12b to be inserted into 6 is formed to protrude downward.

This tapered portion 12b is made of a curved surface with a regular peripheral wall surface, and when the inertial body 12 is displaced, this curved surface does not interfere with the inner surface of the through hole 16 at all, and furthermore, the upper peripheral edge of the hole 16, i.e. The upper edges have curved shapes that do not interfere with each other.
Also, this corner portion 12a is connected to the through hole 16 of the support base 11.
When inserted into the inertial body 12, it is in a floating relationship, and a gap is maintained between its root, that is, its maximum diameter, and the hole diameter of the through hole 16, and when the inertial body 12 is displaced, a slight sliding movement occurs. is allowed. However, although this gap has various advantages which will be described later, it is of course prohibited that it be too large. Usually 0.3~
A thickness of about 0.4 mm is preferable and effective.

Note that the horn portion 12a may be molded integrally with the inertial body 12, or may be made separately and attached as one, but the size of the through hole 16 depends on the size of the inertial body 12 and the sensitivity. It will be easily found in the design by considering the performance.

Furthermore, the actuator 13, which is at least partially in contact with the upper surface of the inertial body 12, can be modified in various ways to suit the shape of the inertial body 12, and various forms shown in FIGS. 4 to 7 are used. These are at least partially in contact with the inertial body 12, and when the inertial body 12 is displaced, they rotate about their shafts 15,
A pawl (not shown) is actuated to engage and lock a ratchet wheel, which is usually fixed coaxially with the belt take-up reel.

The present invention includes the above-mentioned support base 11, inertial body 12,
This effect is achieved by connecting the actuators 13 to each other and incorporating them into a winding device.Next, this effect will be explained in comparison with a conventional sensor using a rolling spherical inertial body.

Figures 8 and 9 show the action of a conventional sensor consisting of a spherical inertial body to be compared, and when it is at rest, the inertial body 2 and the actuator 3 are located at two points P and Q.
The inertial body 2 and the support base 1 are in contact at two points R,
There is contact between S.

At this time, the angular pressure angle formed by the line connecting the center of gravity of the inertial body 2 and each point P, Q of the actuator contact end, and the line connecting the actuator side contact points P, Q and the support base 1 side contact points R, S When θ ₁ and θ ₂ are assumed, the pressure angle becomes smaller if the inertial body 2 is displaced by a predetermined amount (△) as shown in Fig. 9, while the actuator displacement (△S) is determined by the rolling movement of the inertial body 2. At first, there is a large displacement of the actuator, which then becomes smaller and averages out. This shows that although the influence of friction is small when the pressure angle is small, it is susceptible to the influence of friction because the initial pressure angle is large, and at the beginning, the force that starts moving is caused by a large displacement of the actuator. This means that there is a great demand for it.

On the other hand, in the sensor of the present invention shown in FIGS. 10 and 11, when in a stationary state, there is a gap between the root of the tapered part of the bottom surface of the inertial body and the inner surface of the through-hole. Therefore, the force that acts on the inertial body 12 does not act as a force that causes the inertial body 12 to roll from the beginning, but acts as a force that moves the entire inertial body. When the resistance force at the contact point between the body and the actuator becomes large, the inertial body moves, and this initially
Slide the lower part of the inertial body until there is no gap between the two parts. At the point when this gap becomes 0, the resistance force at the point of contact between the inertial body and the support base becomes much larger than the resistance force at the point of contact between the inertial body and the actuator, and as shown in FIG. The body 12 rolls around the contact point as a fulcrum due to the spherical arc surface of its bottom surface.

In this case, since the output is always taken out from a fixed position in the center of the actuator, there is no fluctuation in the omnidirectional actuator and pressure angle.

In both of the above cases, when returning the inertial body, that is, after the sensor is tilted and the actuator is activated, when the sensor is returned to the horizontal direction, the actuator, the inertial body, and the supporting body are Considering it as a wedge, in the case of a conventional spherical inertial body, if the wedge angle _θ3 between the extension of the upper inclined surface of the support base 1 and the contact point is small, as shown in FIG. The force required for return is determined from the interaction between the frictional resistance generated on the contact surface between the actuator 3 and the inertial body 2 due to the load and the frictional resistance between the inertial body 2 and the support base 1.
F ₁ requires a large force, and unless the wedge angle θ ₁ is increased, it will not return unless a large return force is applied to the inertial body 2. However, in the sensor of the present invention, the 13th As shown in the figure, even when the wedge angle θ ₄ is small, the inertial body 12 easily returns to a stable position due to the return force F ₂ due to gravity.

That is, in FIG. 13, when returning, the inertial body 12
The contact point resistance force between the actuator 13 and the inertial body 12 due to the gravity generated in the
When the resistance force at the point of contact with the inertia body 12 becomes smaller than the resistance force at the point of contact with the inertia body 12, the inertia body 12 causes a rolling motion due to the spherical surface of the bottom surface and returns to a stable position without slipping. At this time, part 12
The b side circumferential wall is formed with a curved line that does not interfere with the inner surface of the through hole 16, so that the two portions do not come into contact and create resistance.

When the inertia resistor 12 returns to the support base 11 by rolling motion, the gap between the corner portion 12b and the inner diameter of the through hole 16 is not necessarily averaged over the entire circumference, but may be biased to one side. However, these are eliminated by slipping during the next operation, and there is no effect on the operation at all.

In this way, an acceleration sensitive sensor with excellent dynamic response, good returnability, constant stroke and pressure angle of the actuator in all directions, and little directionality is provided.

As described above, in the sensor of the present invention, at least the bottom surface of the inertial body is formed into a spherical surface centered on the center of gravity of the inertial body, and the top surface of the support base has a slope.
When the inertial body moves to the bottom of the inertial body, the side circumferential wall has a tapered portion formed by a curve that does not interfere with the periphery when the inertial body moves; Since it is characterized by having a gap between the sensors and has the above-mentioned functions, it has the following remarkable effects compared to conventional sensors.

(1) In a conventional sensor that uses the rolling of a spherical inertial body, when the inertial body starts to move, that is, when the force that causes the sphere to move is the smallest, the acceleration and pressure angle of the actuator are at their maximum, and then the maximum value is reached. In contrast to the required force, the sensor of the present invention can increase the amount of displacement of the actuator with a small force at the beginning of movement, and therefore can provide good dynamic response characteristics.

(2) As mentioned above, in the conventional sensor, the pressure angle is maximum at the beginning of movement, and a large pressure angle means that the output given to the driven object will vary greatly depending on the magnitude of the frictional force at the contact point. Because of this, there is a concern that the timing at which it starts moving will be greatly influenced by friction, leading to variations in the time it takes to operate, but the sensor of the present invention has a small pressure angle at the time it starts moving, so the effect of frictional force is small. There is almost no friction, and once relative motion begins between the inertial body and the actuator, the friction becomes dynamic friction and becomes even smaller, creating a more favorable state.

(3) If a conventional sensor with a spherical inertial body is to have no directionality in the stroke of the actuator, it should be designed as shown in Figures 8 and 9, or the pivot point should be in contact with the inertial body. However, in the former case, the pressure angle varies depending on the direction both when stationary and when operating, resulting in a difference in operating time and direction at the start of movement, while in the latter case, the pressure angle varies depending on the direction, while the latter The entire structure becomes large, and all of them are practically unsuitable.

However, since the sensor of the present invention extracts the output from the center while the inertial body is stable, the stroke and pressure angle of the actuator are substantially constant in all directions, and the directivity is significantly reduced.

(4) In the case of using a conventional spherical inertial body, the inertial body does not return unless a large returning force is applied to it, but in the present invention, it returns to a stable state even with a relatively small force, and the operation is stable and reliable. be.

(5) A pivot type sensor like the one shown in Figure 2 not only moves due to acceleration but also moves due to tilt, and the tilt angle appears to have hysteresis, and when returning to its original position, it must first raise the tilted angle and then return to its original position. However, in the sensor of the present invention, hysteresis does not appear and the recovery property is quick and good.

[Brief explanation of the drawing]

1 and 2 are schematic diagrams showing examples of known sensors, FIG. 3 is an exploded perspective view showing an example of a sensor according to the present invention, and FIGS. 4 to 7 are respective implementations of the sensor of the present invention. FIGS. 8 and 9 are diagrams illustrating the operation of the known sensor during displacement operation, and FIGS. 10 and 11 are diagrams illustrating the operation of the sensor of the present invention during displacement operation. Further, FIGS. 12 and 13 are explanatory diagrams of the operation when the inertial body returns, and FIG. 12 shows the case of a known sensor, and FIG. 13 shows the case of the sensor of the present invention, respectively. 1, 1', 11...Support stand, 2, 2', 12...
Inertial body, 12a... Bottom surface of inertial body, 12b... Tapered part, 3, 3', 13... Actuator, 1
6...Support stand through hole.

Claims (1)

[Scope of Claims] 1. An inertial body support base, an inertial body held on the support base and displaced in response to changes in vehicle acceleration, and at least a portion of which is in contact with the upper surface of the inertial body, The inertial body support base includes an actuator that is pivotally supported so as to be able to rotate according to the displacement of the inertial body, and transmits the displacement to the take-up lock means when the inertial body is displaced. The inertial body supporting surface includes the through hole and is an inclined surface that gradually slopes upward radially outward from the through hole, and the inertial body has at least a bottom surface formed by a spherical surface centered on the center of gravity of the inertial body to perform rolling motion on the upper surface of the support base, and a tapered part that is freely inserted into the through hole of the support base at the center of the spherical surface. The peripheral wall on the side of the tongue is a curved surface that does not interfere with the inner surface of the through hole when the inertial body held on the support base rolls on the top surface of the support base. characterized in that when the two parts are inserted into the through-hole of the support base, a gap is provided between the outer periphery of the root part and the periphery of the through-hole to allow the inertial body to slide. Vehicle body acceleration sensing sensor for emergency lock type winding device. 2. The vehicle body of the emergency lock type winding device according to claim 1, wherein the inertial body has a shape with a spherical arc surface formed on the bottom surface of a cylindrical body, and has a tapered portion at the center thereof. Acceleration sensitive sensor. 3. The body of the emergency lock type winding device according to claim 1, wherein the inertial body has a planar shape by cutting off the upper part of a sphere, and has a tapered portion at the center of the bottom part. Acceleration sensitive sensor. 4. Vehicle body acceleration sensitivity of the emergency lock type winding device according to claim 1, wherein the inertial body is a spherical body whose upper part is cut into a V shape, and has a tapered portion at the center of the bottom part. sensor. 5. The emergency lock type according to claim 1, wherein the inertial body is formed with a protruding part on the upper part of the spherical body that contacts the surface facing the recess of the actuator, and has a tapered part at the center of the bottom surface. Vehicle body acceleration sensitive sensor of the winding device.