초록 ▼

A pre-tensioner capable of effectively absorbing kinetic energy exerted on a coupling member connected to a piston during operation. As a gas generator is actuated to generate gas in the event of emergency, the gas is introduced into a pressure chamber. By gas pressure of the gas, a piston moves at

A pre-tensioner capable of effectively absorbing kinetic energy exerted on a coupling member connected to a piston during operation. As a gas generator is actuated to generate gas in the event of emergency, the gas is introduced into a pressure chamber. By gas pressure of the gas, a piston moves at high speed toward a taper portion of a cylinder to reach the taper portion. According to the movement of the piston, a buckle is pulled toward a bracket so that the buckle is about to reach the bottom. After that, the piston further moves to the left while deforming the taper portion. The deformation of the taper portion absorbs kinetic energy of the piston. Therefore, kinetic energy of the buckle is absorbed so as to stop the buckle softly and the impact is buffered.

대표청구항 ▼

What is claimed is: 1. A pre-tensioner comprising: a cylinder; a piston that is slidably disposed in the cylinder and is connected to a coupling member; a cover that is coupled to the coupling member and is contractable to a fully contracted position; and a gas generator which generates gas to act

What is claimed is: 1. A pre-tensioner comprising: a cylinder; a piston that is slidably disposed in the cylinder and is connected to a coupling member; a cover that is coupled to the coupling member and is contractable to a fully contracted position; and a gas generator which generates gas to act on the piston, wherein the gas generator is actuated to generate gas and the piston is moved by gas pressure of the generated gas so as to pull the coupling member so that the coupling member contracts the cover toward the fully contracted position, wherein the cylinder is provided with an impact buffering zone which buffers impact exerted on the coupling member by absorbing kinetic energy of the piston during operation, the impact buffering zone being a tapered portion of the cylinder in which the piston slides through, the impact buffering zone of the cylinder being deformed by movement of the piston so as to buffer the impact on the coupling member, wherein the cylinder is provided with a pre-decelerating zone for decelerating the piston, the pre-decelerating zone comprising annular concavities separated a distance from the tapered portion of the impact buffering zone, and wherein the piston is configured to deform at least a portion of the impact buffering zone prior to the cover reaching the fully contracted position. 2. The pre-tensioner according to claim 1, wherein the pre-decelerating zone is located between the piston and the impact buffering zone, wherein the pre-decelerating zone decelerates the piston before the deformation of the impact buffering zone starts. 3. The pre-tensioner according to claim 2, wherein the pre-decelerating zone of the cylinder is configured to be deformed by movement of the piston, thereby decelerating the piston. 4. The pre-tensioner according to claim 2, wherein the pre-decelerating zone of the cylinder includes a mechanism for discharging a portion of the gas acting on the piston, thereby decelerating the piston. 5. A seat belt system, comprising: a pre-tensioner; and a seat belt connected to the pre-tensioner, wherein the pre-tensioner increases the tension on the seat belt in an emergency condition, wherein the pre-tensioner includes a piston and cylinder arrangement, wherein the cylinder is configured to deform in a deformation portion due to movement of the piston to thereby reduce an impact force on a coupling member connecting the piston to the seat belt, the deformation portion of the cylinder being configured as a tapered portion of the cylinder, wherein the cylinder includes a pre-decelerating zone configured to decelerate the piston, the entire pre-decelerating zone being separated from and positioned before the deformation portion, and the pre-decelerating zone being configured to deform by movement of the piston, wherein the pre-decelerating zone includes annular concavities, and wherein the pre-decelerating zone decelerates the piston before deformation of the cylinder starts. 6. The seat belt system according to claim 5, wherein a length of a deforming section of the cylinder is in the range of 15 mm to 100 mm. 7. A pre-tensioner for a seat belt system, comprising: a piston; a cylinder; a cover that is contractable to a fully contracted position; and a coupling member for connecting the piston to the seat belt and configured to contract the cover toward the fully contracted position upon movement of the piston, wherein the cylinder is configured to be deformed in a deforming section by movement of the piston in an emergency condition to thereby absorb kinetic energy of the piston, the impact buffering zone being a tapered portion of the cylinder in which the piston slides through, wherein the piston is configured to deform at least a portion of the cylinder prior to the cover reaching the fully contracted position, and wherein the cylinder includes a pre-decelerating zone configured to decelerate the piston, the pre-decelerating zone including annular concavities. 8. The pre-tensioner according to claim 7, wherein the pre-decelerating zone is separated from the deforming section of the cylinder and located between the piston and a deforming section of the cylinder. 9. The pre-tensioner according to claim 7, wherein the pre-decelerating zone decelerates the piston before deformation of the cylinder starts.