GB1200654A - Seat belt retractor assembly - Google Patents

Abstract

1,200,654. Safety harness. R. C. FISHER. 26 July, 1967 [10 April, 1967], No. 14600/70. Divided out of 1,200,653. Heading A3V. A seat belt retractor assembly includes a rotatable spool, upon which a seat belt may be wound, a ratchet member rigidly mounted on the spool for rotation therewith, a detent movable between a first position engaging the ratchet to prevent rotation of the spool in one direction of rotation thereof to prevent unwinding of a seat belt therefrom and a second position disengaging from the ratchet to allow rotation of the spool in said one direction and thus unwinding of the seat belt therefrom, a rotatable cam for controlling the movement of the detent between the first and second positions during winding or unwinding of the seat belt from the spool, biasing means for biasing the cam into frictional engagement with the ratchet member and means for limiting rotational movement of the cam. As shown, a shaft 19 extending through a spool 16 is journalled in support plates 29, 34, fixed to a vehicle floor, and carries a gear 65 at one end which engages eccentrically within a gear 67. A detent member 52 journalled in slots 51 in plates 29, 34 includes fingers 53, 54 and is biased towards the first position in which the fingers are in engagement with ratchet teeth 50 on end plates 14, 15 of the spool by a spring 61. One end 62 of the spring embraces a portion 63 of plate 29 and a finger 64 at the other end engages finger 53 of the detent. A cap 44 housing a retraction spring 13 is mounted on the outer side of the support plate 34. A cam 26 journalled on the shaft 19 and retained against the end plate 14 by a spring washer 27 has lobes 76, 80 for engagement with the finger 53 and a finger 49 which moves in a slot 48 in the support plate 29 to limit rotation of the cam 26. Studs 70 on a gear retainer 68 are press fitted in apertures 71 in support plate 29 and an end closure 72 is snapped over the retainer. The gear 67 includes a boss 73 with a cam surface 74 which on rotation of the shaft 19 is moved into and out of engagement with an extension 55 of the detent 52 for moving the detent between the first and second positions. The angular displacement of the boss 73 relative to the detent is small due to the eccentric mounting of the gear 67. During retraction of the belt, (Fig. 6), the detent fingers 53, 54 are held out of engagement with the ratchet teeth 50 by the cam lobe 76. By the time the lobe is fully retracted the boss 73 on the gear 67 has moved into engagement with the detent extension 55 to maintain the fingers 53, 54 out of engagement with teeth 50. When the belt is pulled out the gears 65, 67 rotate clockwise, as seen in Figure 9 and the boss is moved out of engagement with extension 55. The cam has meanwhile also moved clockwise and the lobe 80 engages the finger 53 to maintain the detent in the second position. When enough belt has been withdrawn the spring 13 is allowed to retract the belt slightly. The lobe 80 is immediately disengaged from the finger 53 which is urged by spring 61 into engagement with a ratchet tooth 50. If a large amount of retraction is needed, the spring 13 is allowed to rotate the spool further in the counter clockwise direction until the lobe 76 moves the finger 53 out of engagement with the ratchet tooth, thus allowing the spring 13 to rotate the spool until all slack has been taken up. Thereafter a slight pull on the belt 11 will move the cam lobe 76 out of engagement with the finger 53 and the spring 61 will urge it against a ratchet tooth 50. If the user wants to pull the belt out further, it must first be allowed to retract until the boss 73 engages the detent extension 55 thus moving the detent to the second position. Pull on the belt will then move cam lobe 80 into engagement with the finger 53. When sufficient belt has been pulled out reverse movement of the spool by the spring 13 will move cam lobe 80 to release finger 53 so that the spring 61 can urge the detent 52 into the first position.