WO1997002966A1

WO1997002966A1 - Vehicle sensor inhibitor

Info

Publication number: WO1997002966A1
Application number: PCT/GB1996/001639
Authority: WO
Inventors: Martyn Neil Palliser; Charles Robert Madden
Original assignee: Alliedsignal Limited
Priority date: 1995-07-11
Filing date: 1996-07-09
Publication date: 1997-01-30
Also published as: GB9514095D0; GB2303044A; AU6366196A

Abstract

A vehicle safety restraint retractor comprising a spool for carrying belt webbing (9), a rewind mechanism for rotating the spool to rewind webbing thereon, a vehicle sensor (13) for detecting acceleration and/or deceleration of the vehicle exceeding a predetermined limit, means (1, 2) for locking the spool against rotation when the vehicle sensor (13) detects the predetermined acceleration or deceleration, and a blocking arm (4) for disabling the locking means when the spool is rotating in a rewinding direction, the blocking arm being frictionally coupled to the spool and its movement being limited by arcuately spaced abutments (7, 8). This enables noise to be reduced, particularly to eliminate the ratching noise of the vehicle sensor pawl (1) dragging over the locking teeth (2) on rewind of a seat belt webbing.

Description

VEHICLE SENSOR INHIBITOR DESCRIPTION

The present invention relates to a vehicle sensor inhibitor for a vehicle safety restraint retractor. Safety restraint retractors typically incorporate two sensing mechanisms. One is a belt webbing sensor which detects acceleration of the belt webbing as it is being pulled out when the occupant moves forward and the second is a vehicle sensor which detects the acceleration and deceleration of the vehicle as for example in a collision. When a collision situation is detected the sensors are designed to activate a locking pawl to engage a ratchet wheel connected to the spool and prevent further rotation of the spool, thus preventing undue payout of the webbing and securely retraining the occupant. In a non-crash condition when the seat belt worn by an occupant is released from a buckle attachment fastening it around the occupant, there is a retraction spring in the seat belt retractor which rewinds the belt webbing rapidly back onto a retractor spool. During this rewinding the forces are equivalent to rapid deceleration and the vehicle sensor locking pawl tends to contact the vehicle sensor ratchet wheel which is connected to the spool . This locking pawl rides over the ratchet teeth generating an irritating noise to the vehicle occupant. Similarly even when the seat belt is stationary, e.g. is in its stored position or when the seat belt is being worn by the vehicle occupant, the vehicle sensor can move due to rough road surfaces and this movement can cause the vehicle sensor mass to move the vehicle sensor pawl and cause noise which is equally irritating to the vehicle occupants .

It is an object of the present invention to reduce or eliminate this source of noise in a retractor.

According to the present invention there is provided a vehicle safety restraint retractor comprising a spool for carrying belt webbing, a rewind mechanism for winding the spool to rewind webbing thereon, a vehicle sensor for detecting acceleration or deceleration of the vehicle exceeding a predetermined limit, means for locking the spool against rotation when the vehicle sensor detects the predetermined acceleration or deceleration and a blocking arm for disabling the locking means when the spool is rotating in a rewinding direction, the blocking arm being frictionally coupled to the spool and its movement being limited by arcuately spaced abutments . Preferably a vehicle safety restraint retractor according to the invention comprises a friction drum connected for rotation with the spool and frictionally coupled with the blocking arm by means of resilient biasing elements such as springs . For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made by way of example to the accompanying drawings in which:

Fig. 1 is a part cut-away side view of a retractor according to the present invention with the inhibitor engaged;

Fig. 2 is a part cut-away side view of the retractor of Fig. 1 with the inhibitor disengaged; and

Fig. 3 is a cross-sectional partial view through one end of the retractor of Fig. 1.

Fig. 1 shows webbing 9 being wound onto spool 3 in the direction of arrow 14, during a rewind operation, for example when a vehicle occupant has disengaged the belt buckle and the belt is retracting back into the retractor under the force of a rewind spring which is typically a clock spring attached to one side of the spool 3 (but is not shown here) .

A ratchet wheel 12 with ratchet teeth 2 is fixed for rotation with spool 3. As illustrated in Figs. 1 and 2 this will be in a clockwise direction for rewind, and an anti-clockwise direction for pay-out of the belt webbing. The vehicle sensor 13 consists of an inertial mass in the form of an up-turned cup 18 balanced on a probe or spike 19. It may alternatively use a ball as the inertial mass resting in a cup. When a sudden change of speed occurs, i.e. acceleration or deceleration exceeding predetermined limits indicative of a crash situation, then the standing cup 18 is displaced relative to its support spike 19 which causes lever 17 to be displaced upwardly (as shown in Figure 2) . A pivotally mounted vehicle sensor lever 1 is urged by this displacement into engagement with ratchet teeth 2. When engaged, the ratchet wheel 12 and hence spool 3 is held against rotation and the belt webbing 9 cannot pay out thus it holds the vehicle occupant securely against the effects of a crash. However, the vehicle sensor lever 1 may be displaced even on a normal rewind operation and will catch on the ratchet teeth 2 making an unacceptable noise.

To avoid this an inhibitor is provided comprising a blocking arm 4 which is frictionally coupled to the spool 3 for rotation therewith. Abutments 7 and 8 limit the movement of blocking arm 4 and the friction coupling slips when the arm is prevented from moving by either abutment.

In Fig. 1 the webbing 9 is being rewound so the spool 3 is rotating clockwise and the inhibitor is engaged. In this engagement position the blocking arm 4 rests against abutment 8 which is on the counterarm 15 to the vehicle sensor lever 1 and thus holds the vehicle sensor lever 1 away from the ratchet teeth 2 preventing the unwanted ratcheting noise. The abutment 8 is the limit of the blocking arm 4 movement in the rewind direction. Continued rewind results in the friction drum 5 slipping as the blocking arm 4 remains stationary but the friction drum 5 continues to turn. The blocking arm 4 remains in this position due to the axial friction force of the spring 6. In this position the blocking arm 4 prevents the vehicle sensor mass and vehicle sensor lever from moving and therefore reduces the noise being generated.

In Fig. 2 the webbing 9 is being extracted in the direction of arrow 16, e.g. to fasten the safety belt onto a vehicle occupant or even during normal movement of an occupant wearing the belt. The spool 3 rotates anti-clockwise and the friction coupling pulls the blocking arm 4 anti-clockwise too until its movement is limited by abutment 7 on the lockcup 11 which supports the vehicle sensor. In this position the inhibitor is disengaged so the vehicle sensor lever arm 1 is free to move, i.e. to pivot and thus to engage the ratchet teeth 2 in the event of the vehicle sensor being actuated. Any further extraction of webbing 9 results in friction coupling slipping again with the blocking arm 4 remaining against the abutment 7 on the lockcup 11 but the spool 3 can rotate normally to accommodate an occupant ' s movement . The arc of movement of the blocking arm 4 is shown as α.

Fig. 3 illustrates the friction coupling of the blocking arm 4 with the spool 3 via a friction drum 5 and a spring 6. The spring 6 forces the blocking arm axially out against the friction drum 5 in the direction of arrow 20. The friction drum 5 rotates with the spool 3 and carries the blocking arm 4 but only as far as movement of the arm is not prevented by the abutments 7 and 8. Beyond these abutments, rotation of the spool 3 and friction drum 5 causes the blocking arm 4 to be forced against the abutments 7 and 8 and the friction coupling slips allowing the spool and friction drum to continue to rotate as in normal operation.

Claims

1. A vehicle safety restraint retractor comprising a spool for carrying belt webbing, a rewind mechanism for rotating the spool to rewind webbing thereon, a vehicle sensor for detecting acceleration and/or deceleration of the vehicle exceeding a predetermined limit, means for locking the spool against rotation when the vehicle sensor detects the predetermined acceleration or deceleration, and a blocking arm for disabling the locking means when the spool is rotating in a rewinding direction, the blocking arm being frictionally coupled to the spool and its movement being limited by arcuately spaced abutments .

2. A vehicle safety restraint retractor according to claim 1 comprising a friction drum connected for rotation with the spool and frictionally coupled with the blocking arm by means of resilient biasing elements such as springs.

3. A vehicle safety restraint retractor according to claim 1 or claim 2, wherein the frictional coupling of the blocking arm to the spool is adapted to slip when the blocking arm is prevented from moving by one of the abutments.

4. A vehicle safety restraint retractor according to any preceding claim, wherein one of the abutments is connected to the spool locking means.

5. A vehicle safety restraint retractor according to claim 4, wherein the spool locking means comprises a pawl for engaging teeth on a wheel fixed for rotation with the spool, and the engagement of the blocking arm with the abutment connected to the spool, maintains the pawl out of engagement with the teeth.

6. A vehicle safety restraint retractor according to any preceding claim comprising means to engage the blocking arm with the vehicle sensor to inhibit movement of free parts in the sensor.

7. A vehicle safety restraint retractor according to any preceding claim, wherein one abutment is connected to the vehicle sensor housing.

8. A vehicle safety restraint retractor according to claim 7, wherein the spool is free to rotate in the condition in which the blocking arm engages the abutment connected to the vehicle sensor housing.

9. A vehicle safety restraint retractor according to any preceding claim further comprising a resilient bias means acting in an axial direction between the blocking arm and the spool .