Winding – tensioning – or guiding – Reeling device – With spring motor
Reexamination Certificate
1999-09-21
2001-08-21
Jillions, John M. (Department: 3653)
Winding, tensioning, or guiding
Reeling device
With spring motor
Reexamination Certificate
active
06276626
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention concerns a seat belt retractor, in particular, it concerns a seat belt retractor made so that in a vehicle emergency it absorbs the energy imposed on a passenger by the torsional deformation of the spindle shaft, which functions as a torsion bar, and finally holds the passenger securely in the webbing.
BACKGROUND TECHNOLOGY
Heretofore in a seat belt retractor mounted on a vehicle, when there is a vehicle emergency such as a vehicle collision, an emergency locking mechanism locks the winding drum so that it cannot rotated in the direction by which the webbing would be pulled out, preventing the webbing from being pulled out of the winding drum.
But when the deceleration of the vehicle becomes very high in a vehicle emergency, it is undesirable that the load that a passenger receives from the webbing should become very large. Thus in recent seat belt retractors, an emergency locking mechanism causes the winding drum to get into a roughly locked state, and when the load acting on the webbing becomes large, the energy is absorbed by an energy absorption means while rotation of the winding drum is allowed, thus easing the impact that acts on the passenger.
For example, Japanese Laid-open Patent Publications No. 7-277136 and No. 7-101310 disclose a seat belt retractor in which a deformation member as the energy absorption means is provided around the outside surface of the winding drum. In this seat belt retractor, during a vehicle emergency the winding drum is locked nonrotatably by an emergency locking mechanism, and when a large load acts on the webbing, the deformation member deforms in its diameter-shrinking direction, thus absorbing the energy by the deformation. But a seat belt retractor of this type has a complex structure and is troublesome to assembly.
Meanwhile, Japanese Laid-open Patent Publications No. 6-156884 discloses a seat belt retractor that employs a torsion bar as the energy absorption means. In this seat belt retractor, the torsion bar goes through the winding drum, and one end of it is coupled to the winding drum so that they cannot rotate relative to each other.
A head part is formed on the other end of the torsion bar, and in the state in which this head part is locked nonrotatably by the emergency locking mechanism during a vehicle emergency, when a prescribed load (for example, 4 kN) acts on the webbing, one end of the torsion bar rotates together with the drum, the torsion bar is torsionally deformed, and the energy is absorbed through this torsional deformation. A seat belt retractor that employs this torsion bar is superior in that it has a simple structure and is easy to assemble, and its energy absorption performance is stable and highly reliable.
But with the seat belt retractor of Japanese Laid-open Patent Publications No. 6-156884, when a vehicle emergency occurs, the emergency locking mechanism locks only the head part of the torsion bar, not the end of the torsion bar, so even if a very great load acts on the webbing, rotation of the winding drum is not restricted, hence the torsion bar continues to undergo torsional deformation, and there is risk that the extension of the webbing will exceeds its critical value or that the torsion bar will break, losing the function of restraining the body. In particular, it will easily break when the torsion bar undergoes repeated torsional deformation when, for example, the vehicle, like a billiard ball, collides with one obstruction after another.
The purpose of this invention is, in a seat belt retractor equipped with a spindle shaft that functions as a torsion bar, to absorb the kinetic energy of the passenger during a vehicle emergency and ultimately to securely restrain the passenger with the webbing.
OBJECTS AND SUMMARY OF THE INVENTION
Disclosure of the Invention
The seat belt retractor of this invention — in a seat belt retractor that has a winding drum onto which the webbing winds and a spindle shaft whose end engages with the winding drum to prevent their mutual rotation and which functions as a torsion bar, made so as to absorb energy by torsional deformation of the spindle shaft during a vehicle emergency — has a coupling mechanism whereby at the time of a vehicle emergency, torsional deformation of the spindle shaft is allowed until the torsional deformation rotation of one end of the spindle shaft with respect to the part near the other end reaches a prescribed value, and when the torsional deformation rotation reaches the prescribed value, the part near the other end of the spindle shaft and the winding drum are coupled nonrotatably with respect to each other.
The prescribed value of torsional deformation rotation is a value at which the spindle shaft does not break and is set to a value whereby the passenger does not reach the steering wheel due to the extension of the webbing due to the torsional deformation of the spindle shaft. The load that acts on the passenger from the webbing when the spindle shaft undergoes torsional deformation can be appropriately set by appropriately designing the spindle shaft of the right shape and material, etc.
In this seat belt retractor, one end of the spindle shaft engages with the winding drum so that they cannot rotate with respect to each other, and thus in a vehicle emergency the rotation of the other end of the spindle shaft is locked by some sort of emergency locking mechanism, and when a large load, for example 4 kN or more, acts on the webbing, the winding drum rotates together with the one end of the spindle shaft, which torsionally deforms, absorbing energy by its torsional deformation. Thereafter, when the torsional deformation rotation reaches a prescribed value, the part near the other end of the spindle shaft and the winding drum are coupled by a coupling mechanism so that they cannot rotate relative to each other, the winding drum no longer rotates, extension ofthe webbing from the winding drum is prevented, and the passenger is securely restrained by the webbing.
Therefore, if a very large load acts on the webbing during a vehicle emergency, or even if the vehicle collides multiple times and the spindle shaft undergoes repeated torsional deformation, the kinetic energy of the passenger is absorbed, breakage of the spindle shaft is surely prevented, and finally the passenger can be securely restrained by the webbing, thus making it possible to surely prevent secondary impact of the passenger with the steering wheel or windshield and ensuring the safety of the passenger.
The seat belt retractor of another mode of this invention has—in a seat belt retractor that absorbs energy by the torsional deformation of a torsion bar in a vehicle emergency—a winding drum on which the webbing is wound; a spindle shaft that is positioned to pierce this winding drum, and whose one end engages with the winding drum so that they cannot rotate relative to each other, and that has a torsion bar part; an emergency locking means that nonrotatably locks the part near the other end of the spindle shaft when a vehicle emergency occurs; and a coupling mechanism that, following operation of the emergency locking means, causes the winding drum and one end ofthe spindle shaft to rotate integrally by the tension acting on the webbing and allows torsional deformation of the spindle shaft until the torsional deformation rotation ofone end of the spindle shaft with respect to the part near the other end in the webbing pull-out direction reaches a prescribed value, and, when the torsional deformation rotation reaches the prescribed value, couples the part near the other end of the spindle shaft and the winding drum so that they cannot rotate relative to each other.
As stated above, the prescribed value of the torsional deformation rotation is a value at which the spindle shaft does not break and is set to a value whereby the passenger does not reach the steering wheel due to the extension of the webbing due to the torsional deformation of the spindle shaft. Also, the load that acts on the passenger from the webbing when the spindle shaf
Nishikawa Masao
Tanaka Hiroshi
Ashimori Kogyo Kabushiki Kaisha
Jillions John M.
Morrison Law Firm
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