GB1568765A - Safety belt tensioning and rewinding retractor - Google Patents

Description

PATENT SPECIFICATION

( 11) 1 568 765 Application No 1743/79 ( 22) Filed 26 Jul 1977 ( 19) Divided out of No 1568763 ( 31) Convention Application No's 751753 ( 32) Filed 17 Dec 1976 791477 27 Apr 1977 in ( 33) United States of America (US) ( 44) Complete Specification Published 4 Jun 19 ()8 ( 51) INT CL 3 A 62 B 35/02 Index at Acceptance A 3 V SG ( 54) SAFETY BELT TENSIONING AND REWINDING RETRACTOR ( 71) We, AMERICAN SAFETY EQUIPMENT CORPORATION, a corporation organised and existing under the laws of the State of New York, United States of America, of 10655 Ventura Boulevard, Encino, California 91316, United States of America, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed to be particularly described in and by the following statement:This invention relates in general to safety belt tensioning and rewinding means for retractors employed in storing safety belts of safety harnesses utilized in vehicles for restraining a passenger in his seat during emergency conditions and more specifically.

to such means for applying a lower tension on the safety belt when unwound to a position of use than normally applied to remind the belt.

Emergency locking retractors normally used in safety harness systems employed in vehicles currently are of the emergency locking type, i e the retractor locks against further belt unwinding or protraction only in the event of an emergency condition which may be sensed due to strap acceleration as the persons body moves forward pulling the strap out of the retractor or in response to changes in vehicle acceleration sensed by an inertia sensor or mass associated with the retractor In such emergency locking retractors, the seat belt webbing or belt is free to move in and out under normal occupant movement subject to the rewind bias of the retractor rewind spring Tension applied to the belt by virtue of the bias of the rewind spring required for rewinding long lengths of webbing or safety belt employed in safety harness systems can be objectionable to the suer Therefore various arrangements have been made heretofore for reducing the tension applied to the belt by the rewind spring when the belt is placed in use.

In accordance with the present invention there is provided a safety belt retractor comprising a frame, a safety belt storage reel rotatablv mounted on the frame, biassing means for biasing the belt in a belt rewind direction at a first level of bias, the biasing means being actuable to apply a second lower level of rewind bias to the reel the biasing means including constant torque means coupled to the reel for applying the lower level of rewind bias to the reel whereby a substantially constant torque is applied to the reel during reel rotation when the biasing means is actuated to apply the lower level of bias.

A better understanding of the invention will be had from the following details description given by way of example with reference to the accompanying drawings, in which:Figure 1 is a plan view of a safety belt retractor in accordance with the present invention:

Figure 2 is a side view of the retractor of Figure 1 taken therein along the plane II-II showing the retractor in a comfort zone mode:

Figure 3 is a section view of the retractor of Figure 2 taken therein along the plane Ill-Ill:

Figure 4 is a view of the retractor as in Figure 2 showing the retractor in a belt unwinding mode:

Figure 5 is a view of the retractor as in Figure 2 showing the retractor in a belt rewinding mode:

Figure 6 is a section view of the retractor of Figure 2 taken theren along the plane VI-VI:

Fhiure 7 is a section view of the retractor of Figure 4 taken therein along the plane VII-VII:

Figure 8 is a detail section view of a portion of the retractor of Figure 5 taken v),( ( 21) ( 62) ( 52) 1 568 765 therein along the plane VIII-VIII:

Referring initially to Figure 1, the retractor indicated generally at 10 as is conventional in emergency locking retractors, includes a generally U-shaped frame 11 having base 12 and side walls 13 and 14 Safety belt 15, which may be part of a safety harness or belt system as known in the industry, is wound upon the reel, indicated generally at 16, of the retractor as best seen in Figures 2 and 3 The reel includes a pair of spaced ratchet wheels 17 and 18 fixed upon shaft 21 which in turn is mounted by bushings as bushing 20 to the retractor frame side walls 17 and 18 Spool 19 is fixed to ratchet wheels 17 and 18 in conventional manner.

Emergency locking means are provided in the examplary retractor as indicated generally at 25 Such means in the exemplary embodiment includes a locking pawl bar 26 pivotally mounted between frame side walls 13 and 14 for engagement with the respective ratchet wheels 17 and 18 on tilting movement of bar 26 A pendulum-like inertia sensor mass 27 is suspended from support bar 28 to place a head portion thereof beneath bar 26 to cause tilting movement of bar 26 to lock the retractor against further belt unwinding on swinging movement of pendulum 27 as during a deceleration of the vehicle in an emergency situation The retractor construction explained thus far is considered conventional.

Safety belt tensioning and rewind means are provided for normally causing belt 15 to be rewound into a stored condition on reel 16 and importantly to provide for a reduced tension effect on belt 15 when placed in use by an occupant of a vehicle in which the retractor is utilized An exemplary safety belt tensioning and rewinding means is indicated generally at 30 in Figure 1 within housing 31 which includes an upper generally cylindrical portion 32 and a lower, laterallv displaced smaller generally cylindrical portion 33 As seen in Figures 2 and 3.

housing 31 includes a base 34 by which the housing is mounted to frame side wall 13 and retained there via suitable fasteners as fasteners, 35 36 and 37 which in the exemplary embodiment may include head bolts threaded through base 34 into retractor side wall 13 As best seen in Figure 2 a port 38 allows communication between the two housing portions 32 and 33 for purposes as will become apparent subsequently.

First biasing means for biasing the safety belt reel 16 toward a belt storage condition is provided within housing portion 32 In the exemplary embodiment such first biasing means comprises a main rewind spring 4 () which is of coil configuration having its inner end 41 connected to shaft 21 via slot 23, An outer end 42 as seen in Figure 2 is connected to member 50 whose function will be described subsequently.

As best seen in Figures 2 and 3 member is rotatablv mounted relative to shaft 21.

and in the exemplary embodiment, is of drum-like configuration having a cylindrical outer wall 51 provided with a slot 52 which received the outer end 42 of the rewind spring 40 Drum member 50 is further provided with a cylindrical web 53 which has a central aperture mounted upon and rotatable relative to an inner bushing portion 54 of bushing 55 which is fixed via web 56 in non-rotatable relation to shaft 21.

From the foregoing, it can be seen that spring 40 normally biases member 50 in a clockwise direction and shaft 21 in a counter-clockwise, webbing rewind, direction in Figures 2 4 and 5 However, means are provided for limiting the clockwise rotation of member 50 such means in the exemplary embodiment: including the provision of bumper 57 upon web of member 50 and a co-operating stop or abutment 58 formed integrally of housing 31 Stop or abutment 58 is provided with a resilient stop member 59 against which bumper 57 may abut, as seen in Figure 4 to limit clockwise rotation of member 5 () during an unwinding of belt off reel 16 against the bias of main spring 40.

Means are provided for releasablv connecting member 50 to reel 16 to block the bias of rewind spring 40 and thus relieve belt 15 of tension due to the spring bias, when belt 15 has been unwound to a position of use Such connecting means in the exemplary ebodiment is indicated generally at 60 and includes the provision of pawl 61 mounted by mounting pin 62 for pivotal movement on web 53 of member 50 A ratchet 63 of wheel or gear-like configuration is formed integrally of bushing 55 as seen in Figures 2 and 3, with teeth 64 facing in a counterclockwise direction in Figure 2 for engagement by pawl tooth 65 as seen in Figure 2 When pawl 61 engages ratchet 63 as seen in Figure 2 member 50 is thus connected to shaft 21 and reel 16 in a manner preventing relative rotation due to the bias of main spring 40 The connecting means indicated generally at 60 may thus be considered a means for blocking out the bias of the first biasing means which in the exemplarv embodiment comprises coil spring 40).

The operation of pawl 61 between engagements and disengagements with ratchet 63 as will be explained more fully hereinafter is in part controlled by a spring wire combination clutch and cam means 70 which has a circular body portion mounted in arook e 71 of member 55 to provide a frictionally driven relation to cam means means 70 in response to rotation of reel 16.

1 568 765 Combination clutch and cam means 70 is further provided with cam arm portions 72 and 73, as seen in Figure 2, for engaging cam follower pin 66 provided on pawl 61.

During a normal unwinding operation of reel 16, as seen in Figure 4, cam arm 72 will move cam follower pin 66 to the position shown in figure 4 holding pawl 61 out of engagement with ratchet 63 and thus allowing the rewind bias of main spring 40 to be applied to belt 15 as belt 15 is unwound fronm the reel 16 However, on a slight rewinding movement of belt 15, as normally occurs during buckling up of a safety belt harness is employing a safety belt as belt 15, the reel will move in a rewind direction from the position of Figure 4 toward the position of Figure 2 causing cam arm 72 to relieve cam follower pin 66 and alow pawl 61 to fall into engagement with ratchet 63 Such engagement occurs with bumper 57 still engaging member 59 of stop 58 with subsequent movement of member 50 and reel 16 in a counterclockwise direction from the position of Figure 4 to the position of Figure 2 being under the urging of the second biasing means in accordance with the present invention as will now be explained.

A reduced tension effect is provided in the exemplary embodiment of retractor when the bias of the aforedescribed first biasing means is blocked out through the interconnection of member 50 and reel 16 and in the present exemplary embodiment.

comprises the provision of a second biasing means in a manner hereafter explained for biasing member 50 in a belt rewind direction whereby reel 16 when so connected to member 50, is biased in a rewind direction by a lower biasing effect fo such second biasing means Referring to Figures 2 and 3.

in the exemplary embodiment, such second biasing means is indicated generally at 80 and includes a constant torque spring 81 of coil configuration with its main body portion positioned loosely within the laterally disposed smaler housing portion 33 with an inner end 82 merely left free The second spring means 81 is positioned laterally of first spring 40 with their axes parallel and spaced laterally of one another in a direction normal to the axis of the reel shaft 21 This construction allows the positioning of the two spring means in a flatter or narrower housing mounted to the side wall 13 as is seemed desirable for such retractors which are to be fitted into fairly small or compact locations in a vehicle in which the retractor is to be utilized As further seen in Figures 2 and 3, second spring 81 is of serpentine configuration is that it winds from housing portion 33 through port 38 and into the larger housing portion 32 where its outer end 84 is secured to member 50 via slot 85 with outer end portions 86 of spring 81 encircling member 50 when member 50 is in the position as seebn in Figure 4 during belt unwinding The bias of second spring 81 is thus in a counterclockwise direction in Figures 2 and 4 a direction opposite to the bias of first spring 40 on member 50.

As should be apparent from the foregoing during an initial belt unwinding of belt 15 to a location of use, the retractor mode is as illustrated in Figure 4 with member 5 () being restricted in its clockwise rotation due to the engagement of bumper 57 with stop member 59 second spring 81 having been unwound against its bias and main spring 40 tending to cause rewind of reel 16 On a slight rewind movement of belt cam means 70 releases pawl 61 as aforedescribed to allow pawl 61 to moe from the position of;figure 4 to a position engaging ratchet 63 as seen in Figure 2.

With the bias of main spring 40 thus blocked the retractor is placed in a -low tension zone or lower tension bias by the action of the smaller coil spring 81 which tends to move member 5 ( 1 and interconnected reel 16 in a lower tension rewind direction as illustrated in Figure 2 toward the pawl release position of Figure 5 When the position of Figure 5 is reached, the pawl 61 is released as subsequently described, allowing for a rewind of belt 15 under the bias of main spring 4 ( 0.

When the exemplary retractor is in the "low tension" mode as seen in Figure 2 the lower tensioning effect on belt 15 due to the lower bias of spring 81 maintains the seat belt 15 snug against the users body, which would be the chest when belt is part of a typical vehicle safety harness of the three point emergency locking type currently in use Such reduced tensioning of belt 15 will continue in the retractor construction of the current embodiment for up to nearly a revolution of teel 16 in a counterclockwise direction from the position of Figure 2 to the position of Figure 5 Cam means, indicated generally at 75 are mounted to the retractor frame to be engaged by a portion of pawl 61 upon rotation of member 5 () to the position of Figure 5 in order to release pawl 61 from engagement with a ratchet 63 As seen in Figures 2 4 and 5 the cam means indicated generally at 75 comprises an arcuate body 76 having an inwardly facing cam surface 77 which is engaged bv the cam follower rear end portion 67 of pawl 61 Cam surface 77 progresses radially inwardly from its leading end 78 in a counterwise direction in figure 5 so that cam follower portion 67 pivots pawl 61 out of engagement with ratchet teeth 64 by the time member 5 ( 1 has rotated to almost a full counter revolution as seen in Figure 5.

A recess 68 is preferably provided in the rear end of pawl 61 to provide a surface to abut against limit member 69 which pre4 1 568 765 4 vents over pivoting of pawl 61 As is preferred in accordance with the present invention, cam means 75 and bumper stop 58 are formed integrally of each other and of housing 31.

On release of pawl 61 from ratchet 63 the stronger rewind bias of spring 40 will cause an unwinding of smaller spring 81 to bring member 50 back to the position of Figure 4 and to allow rewinding of webbing 15 under the strong rewind bias of spring 4 ( O Specifically as seen in Figure 5 when pawl 61 is released from ratchet 63 spring 40 tends to turn bushing 55 counterclockwise and member 50 clockwise causing cam arm 73 to engage cam pin 68 As member 50 returns to the position of Figure 4 combination clutch and cam means 70 is returned, via the engagement between pawl pin 68 and cam arm 73 as well where it will continue to hold pawl 61 unlocked from ratchet 63 during a continuing full rewind of webbing 15 on reel 16 Subsequently on pulling of belt 15 outwardly of the retractor clutch and cam means 70 will move to the position of Figure 4 to hold pawl 61 unlocked until there is a subsequent slight retractive movement of belt 15 as seen in Figure 2.

The above described safety belt retractor is also described and claimed in the Complete Specifications of our copending Applications Nos 31386177 (Serial No 1568763) and 1742/79 (Serial No 1568764).

Claims (4)

WHAT WE CLAIM IS:-

1 A safety belt retractor comprising a frame, a safety belt storage reel rotatably mounted on tfie frame biasing means for biasing the belt in a belt rewind direction at a first level of bias, the biasing means being actuable to apply a second, lower level of rewind bias to the reel the biasing means including constant torque means coupled to the reel for applying the lower level of rewind bias to the reel whereby a substantiallv constant torque is applied to the reel during reel rotation when the biasing means is actuated to apply the lower level of bias.

2 A retractor according to Claim 1.

wherein the constant torque means comprises a spring of coil configuration positioned loosely within a housing.

3 A retractor according to Claim 2.

wherein the biasing means comprises coil spring means for applying the first level of rewind bias to the reel, a member is rotatablv mounted to the frame and is rotatable relative to the reel, the coil spring means is connected between the member and the reel, means are provided for limiting rotation of said member in the direction of rotation during unwinding of the belt from the reel whereby the coil spring means biases the reel in the rewinding direction.

blocking means is provided for locking the member against rotation relative to the reel to block the bias of the coil spring means, and constant torque spring is connected to said member.

4 A retractor according to Claim 3.

wherein the constant torque spring has a coil portion disposed laterally of the member and a portion wound about the member.

A.A THORNTON & CO Chartered Patent Agents.

Northumberland House, 303/306 High Holborn.

London WC 1 V 7 LE.

Printed for Her Majesty's Stationery Office.

by Croydon Printing Company Limited, Croydon, Surrey, 1980.

Published by The Patent Office, 25 Southampton Buildings, London, WC 2 A l AY, from which copies may be obtained.

1 568 765