Webbing tension device

Claim 2

A webbing tension device adapted for use in a webbing retractor for protecting an occupant in an emergency situation of a vehicle, which comprises: (a) a wheel supported by a webbing takeup shaft of the webbing retractor; (b) first resilient means biasing the wheel in a direction of a retraction of an occupant restraining webbing; (c) a pawl caused to latch to a portion of the wheel, thereby preventing the wheel from its rotation; (d) cam means abutting on the pawl to support it, thereby maintaining a latching situation of the pawl and the wheel, the cam means allowing the pawl to be released from the wheel when the cam means is rotated in one direction; (e) trigger means causing the cam means to rotate in the one direction to release the pawl from the wheel in the emergency situation of the vehicle, the trigger means having a reversible structure including an acceleration sensor detecting the emergency situation of the vehicle, a trigger member opposed to the cam means and rotated by the acceleration sensor in the emergency situation of the vehicle and second resilient means biasing the trigger member, the direction of the biasing force of the second resilient means being reversed at a pedetermined rotated position of the trigger member; and (f) clutch means connecting the wheel to the takeup shaft to transmit a biasing force of the first resilient means to the takeup shaft when the wheel is rotated, whereby the pawl and the wheel are securely latched to and released from each other.

Claim 3

A webbing tension device as set forth in claim 1, wherein the cam means is rotatably supported by a support means and it is formed with a projection portion projecting in an axial direction of the support means, whereby a forward end portion of the pawl is caused to abut on the projection portion so that the pawl prevents the wheel from rotating in the ordinary running situation of the vehicle.

Claim 4

A webbing tension device as set forth in claim 2, wherein the cam means is formed with a first groove about the support means and a protrusion provided at the forward end portion of the pawl is received in the first groove, whereby the latching situation of the pawl and the wheel is maintained in the ordinary running situation of the vehicle.

Claim 5

A webbing tension device as set forth in claim 3, wherein the cam means if formed with a second groove communicating with the first groove, whereby the protrusion of the pawl is moved from the first groove to the second groove in the emergency situation of the vehicle.

Claim 6

A webbing tension device as set forth in claim 4, which further comprises a third resilient means biasing the takeup shaft in the direction of the retraction of the webbing, the biasing force of the third resilient means being weaker than that of the first resilient means, whereby the takeup shaft is always slightly biased in the direction of the retraction of the webbing so that the webbing fastened about the occupant is taut.

Claim 7

A webbing tension device as set forth in claim 5, wherein the takeup shaft is fixed at one end with one end of a rod coaxially therewith, the first resilient means is supported at one end by an intermediate portion of the rod, and the third resilient means is fixed at one end to the other end portion of the rod.

Claim 8

A webbing tension device as set forth in claim 6, wherein the pawl presses the cam means in the direction of the acceleration sensor in the ordinary running situation of the vehicle, and the cam means is rotated in the reverse direction thereto by the acceleration sensor through the trigger member in the emergency situation of the vehicle.

Claim 9

A webbing tension device as set forth in claim 7, wherein the first and third resilient means are spiral springs, the second resilient means is a coil spring and the acceleration sensor is a pendulum.

Claim 10

A webbing tension device adapted for use in a webbing retractor for protecting an occupant in an emergency situation of a vehicle, which comprises: (a) a wheel supported by a webbing takeup shaft, the takeup shaft being rotatably supported by a frame fixed to a vehicle body and retracting an occupant restraining webbing thereon; (b) first resilient means biasing the wheel in a direction that will cause the retraction of the webbing; (c) a pawl caused to latch to a portion of the wheel, thereby preventing the wheel from its rotation; (d) cam means abutting on the pawl to support it, thereby maintaining a latching situation of the pawl and the wheel, the cam means allowing the pawl to be released from the wheel when the cam means is rotated in one direction; (e) trigger means causing the cam means to rotate in one direction to release the pawl from the wheel in an emergency situation of the vehicle, the trigger means having a reversible structure including an acceleration sensor detecting the emergency situation of the vehicle, a trigger member opposed to the cam means and rotated by the acceleration sensor in the emergency situation of the vehicle and second resilient means biasing the trigger member, the direction of the biasing force of the second resilient means being reversed at a predetermined rotated position of the trigger member; (f) clutch means connecting the wheel to the takeup shaft to transmit a biasing force of the first resilient means to the takeup shaft when the wheel is rotated; and (g) third resilient means biasing the takeup shaft in the direction that will cause the retraction of the webbing, the biasing force of the third resilient means being weaker than that of the first resilient means, whereby the pawl and the wheel are securely latched to and released from each other.

Claim 11

A webbing tension device adapted for use in a webbing retractor for protecting an occupant in an emergency situation of a vehicle, which comprises: (a) a wheel supported by a webbing takeup shaft, the takeup shaft being rotatably supported by a frame fixed to a vehicle body and retracting an occupant restraining webbing thereon; (b) first resilient means biasing the wheel in a direction that will cause the retraction of the webbing; (c) a pawl caused to latch to a portion of the wheel, thereby preventing the wheel from its rotation; (d) cam means abutting on the pawl to support it, thereby maintaining a latching situation of the pawl and the wheel, the cam means allowing the pawl to be released from the wheel when the cam means is rotated in one direction; (e) trigger means causing the cam means to rotate in one direction to release the pawl from the wheel in an emergency situation of the vehicle, the trigger means having a reversible structure including an acceleration sensor detecting the emergency situation of the vehicle, a trigger member opposed to the cam means and rotated by the acceleration sensor in the emergency situation of the vehicle and second resilient means biasing the trigger member, the direction of the biasing force of the second resilient means being reversed at a predetermined rotated position of the trigger member; (f) clutch means connecting the wheel to the takeup shaft to transmit a biasing force of the first resilient means to the takeup shaft when the wheel is rotated; and (g) third resilient means biasing the takeup shaft in the direction that will cause the retraction of the webbing, the biasing force of the third resilient means being weaker than that of the first resilient means, whereby the pawl and the wheel are securely latched to and released from each other.

Claim 12

A webbing tension device as set forth in claim 9, wherein the cam means is rotatably supported by a support means and it is formed with a projection portion projecting in an axial direction of the support means, whereby a forward end portion of the pawl is caused to abut on the projection portion so that the pawl prevents the wheel from rotating in the ordinary running situation of the vehicle.

Claim 13

A webbing tension device as set forth in claim 10, wherein the cam means is formed with a first groove about the support means and a protrusion provided at the forward end portion of the pawl is received in the first groove, whereby the latching situation of the pawl and the wheel is maintained in the ordinary running situation of the vehicle.

Claim 14

A webbing tension device as set forth in claim 11, wherein the cam means is formed with a second groove communicating with the first groove, whereby the protrusion of the pawl is moved from the first groove to the second groove in the emergency situation of the vehicle.

Claim 15

A webbing tension device adaped for use in a webbing retractor for protecting an occupant in an emergency situation of a vehicle, which comprises: (a) a frame fixed to a vehicle body; (b) a takeup shaft rotatably supported by the frame and retracting an occupant restraining webbing thereon; (c) a wheel supported by the takeup shaft; (d) a first spring biasing the wheel rotatively in a direction that will cause the retraction of the webbing; (e) a pawl caused to latch to a portion of the wheel, thereby preventing the wheel from rotating in an ordinary running situation of the vehicle; (f) trigger means detecting an acceleration and deceleration acting upon the vehicle to act to release the pawl from the wheel in the emergency situation of the vehicle and having a reversible structure including an acceleration sensor having a head portion and a trigger member abutting on said head portion of the acceleration sensor, the trigger member comprising a trigger lever and a second spring biasing said lever and the biasing force of the second spring to the trigger lever being reversed when the trigger lever is rotated across a predetermined position; (g) cam means abutting on the pawl to support it, thereby maintaining a latching situation of the pawl and the wheel in the ordinary running situation of the vehicle, the cam means being rotatively pressed on to the acceleration sensor by the first spring through the pawl in the ordinary running situation of the vehicle and in the emergency situation of the vehicle the cam means being rotated to release the pawl from the wheel by the acceleration sensor through the trigger lever; and (h) clutch means connecting the wheel to the takeup shaft to transmit a biasing force of the first spring to the takeup shaft when the wheel is rotated.

Claim 16

A webbing tension device adaped for use in a webbing retractor for protecting an occupant in an emergency situation of a vehicle, which comprises: (a) a frame fixed to a vehicle body; (b) a takeup shaft rotatably supported by the frame and retracting an occupant restraining webbing thereon; (c) a wheel supported by the takeup shaft; (d) a first spring biasing the wheel rotatively in a direction that will cause the retraction of the webbing; (e) a pawl caused to latch to a portion of the wheel, thereby preventing the wheel from rotating in an ordinary running situation of the vehicle; (f) trigger means detecting an acceleration and deceleration acting upon the vehicle to act to release the pawl from the wheel in the emergency situation of the vehicle and having a reversible structure including an acceleration sensor having a head portion and a trigger member abutting on said head portion of the acceleration sensor, the trigger member comprising a trigger lever and a second spring biasing said lever and the biasing force of the second spring to the trigger lever being reversed when the trigger lever is rotated across a predetermined position; (g) cam means abutting on the pawl to support it, thereby maintaining a latching situation of the pawl and the wheel in the ordinary running situation of the vehicle, the cam means being rotatively pressed on to the acceleration sensor by the first spring through the pawl in the ordinary running situation of the vehicle and in the emergency situation of the vehicle the cam means being rotated to release the pawl from the wheel by the acceleration sensor through the trigger lever; and (h) clutch means connecting the wheel to the takeup shaft to transmit a biasing force of the first spring to the takeup shaft when the wheel is rotated.

Claim 17

A webbing tension device as set forth in claim 13, wherein the cam means is rotatably supported by a support means and it is formed with a projection portion projecting in an axial direction of the support means, whereby a forward end portion of the pawl is caused to abut on the projection portion so that the pawl prevents the wheel from rotating in the ordinary running situation of the vehicle.

Claim 18

A webbing tension device as set forth in claim 14, wherein the cam means is formed with a first groove about the support means and a second groove communicating with the first groove, a protrusion formed at the forward end portion of the pawl is received in the first groove in the ordinary running situation of the vehicle and it is moved to the second groove in the emergency situation of the vehicle.

Claim 19

A webbing tension device as set forth in claim 15, which further comprises a third spring biasing the takeup shaft in the direction that will cause the retraction of the webbing, the biasing force of the third spring being weaker than that of the first spring, whereby the takeup shaft is always biasing slightly in the direction of the retraction of the webbing so that the webbing fastened about the occupant is taut.