Safety Belt Clamp Apparatus, Occupant Restraint System and Method

The present invention relates to an improved belt clamp apparatus and to an improved vehicle occupant restraint system having a safety belt which is movable through the clamp apparatus. The belt clamp apparatus applies a substantially uniform force over an area of contact on the belt.

The belt clamp apparatus is an improvement of a belt clamp apparatus described in U.S. Pat. No. 3,847,434 issued Nov. 12, 1974 to Per Olof Weman.

A first and primary object of the present invention is to reduce forward displacement of an occupant, either passenger or driver, in a vehicle, such as an automobile or truck. A second object is to provide a restraint system which may use a simpler, inexpensive retractor. A third object is to provide a reusable restraint system which can absorb some of the force applied on a safety belt and thereby reduce the force felt by the occupant .

FIGS. 1 and 3 are vertical sections of a belt clamp apparatus.

FIG. 2 is a perspective view of a portion of the apparatus of FIGS. 1 and 3.

FIG. 4 is a horizontal section along the lines 4--4 in FIG. 3.

FIG. 5 is a side view of the belt clamp apparatus shown in FIG. 3.

FIG. 6 is a partial horizontal section along the lines 6--6 in FIG. 5.

FIG. 7 is a horizontal section along the lines 7--7 in FIG. 1.

FIGS. 8, 9 and 10 are perspective views of an improved occupant restraint system in a vehicle using the improved belt clamp apparatus of FIGS. 1-7.

In a belt clamp apparatus of the present invention, a safety belt is movable through the apparatus in a first direction and in an opposite second direction. The clamp apparatus stops movement of the belt in the first direction when a force above a predetermined amount is applied to the belt in the first direction. The clamp apparatus includes a lever pivotable on a first shaft and having a clamping position and a non-clamping position.

The improvement of the present invention includes: a clamp means, a mounting means on the lever, a first biasing means biasing said lever to its non-clamping position and a crest on the clamp means. The clamp means has a first surface for contacting a portion of the belt. The mounting means on the lever movably mounts the clamp means on the lever. The clamp means is movable on the crest with respect to the lever for applying a substantially uniform force across an area of contact on the belt. The clamp apparatus may further include a pivot means for moving a portion of the apparatus in a substantially vertical plane and a swivel means for moving a portion of the apparatus in a substantially horizontal plane. The clamp apparatus may further include resilient bushing means within the lever for evenly distributing force applied by the lever laterally across the width of the belt.

The belt clamp apparatus of the present invention may be used in a variety of ways in an improved safety restraint system for a vehicle, such as to provide: a belt sensitive safety restraint system, a vehicle sensitive safety restraint system, a dual sensitive safety restraint system, or a force limiting safety restraint system. If a belt sensitive safety restraint system is desired, the retractor may be a non-locking retractor and the belt clamp apparatus provides the system with belt sensitive capability. In response to a force above a first predetermined amount, the belt clamp apparatus clamps against the safety belt, stopping further movement of the belt through the belt clamp apparatus in the first direction.

If a vehicle sensitive safety restraint system is desired, the belt clamp apparatus may be used in combination with a vehicle sensitive retractor. The belt clamp apparatus is arranged so that a comparatively high amount of force is required to move the belt clamp apparatus into its clamping position. As a result, the vehicle sensitive retractor comes into play before the belt clamp apparatus. If a dual sensitive safety restraint system is desried, the belt clamp apparatus may be used in combination with a vehicle sensitive retractor. The belt clamp apparatus 2 provides the restraint system with its belt sensitive capability. The vehicle sensitive retractor provides the safety restraint system with its vehicle capability.

If a force limiting safety restraint system is desired, the safety belt apparatus may be used in conjunction with a belt sensitive retractor. When a force above a first predetermined amount is exerted on the belt, the belt clamp apparatus clamps against the belt and prevents further movement of the belt through the clamp apparatus until the force on the belt reaches a second predetermined amount, which is greater than the first predetermined value. The belt clamp apparatus has means responsive to the force on the belt above the second predetermined amount to allow controlled slippage of the belt through the belt clamp apparatus, thereby absorbing some of all of the force above the second predetermined amount. If the force on the belt reaches a third predetermined amount which is in excess of the second predetermined amount, the belt sensitive locking mechanism in the retractor comes into play. The belt sensitive mechanism in the retractor locks in response to the force above the third predetermined amount, thereby preventing further unwinding of the belt from the retractor. The retractor in the force limiting system may be dual sensitive.

Controlled slippage of the web through the belt clamp apparatus may be achieved by: changes in design within the belt clamp apparatus, such as by varying the leverage of the lever; by varying the frictional force of the clamping portion; or a change in the included angle of the belt passing through the clamp apparatus; or changes in the surface characteristicracteristics of the belt.

The safety belt may further include an inflatable portion and means for inflating it. The invention also includes: a method for absorbing unwinding force resulting from a pull on the safety belt when an occupant lurches forward against the belt; and a method for reducing undesired unwinding of the belt from a retractor in a safety restraint system after a locking action has been applied to the belt within the retractor and reducing undesired elongation of the belt between the retractor and the occupant.

Referring to FIG. 1, the belt clamp apparatus, referred to generally by the numeral 2, may be used with a vehicle occupant restraint system having a shoulder belt 4. For example, the belt clamp apparatus 2 may be used as a substitute for a bracket means in a restraint system described in U.S. Pat. No. 3,847,434. The belt 4 is movable throughout the belt clamp apparatus 2 in a first unwinding direction 6 in which the belt 4 becomes more loose around the occupant and in an opposite second winding direction 8 in which the belt 4 becomes tighter around the occupant. The belt clamp apparatus 2 includes a lever 10 pivotable on a first shaft 36. The belt clamp apparatus 2 resists movement of the belt 4 in the first unwinding direction 6 when a force above a predetermined amount is applied to the belt 4 in the unwinding direction 6. The lever 10 has a clamping position shown in FIG. 5 and a non-clamping position, shown in FIGS. 1 and 3.

The improvement of the present invention includes a clamp means such as a clamp bar 12, a mounting means, referred to generally by the numeral 14, for the clamp bar 12 adjacent to a lower end of the lever 10, a longitudinal crest 16 along the longitudinal axis of the clamp bar 12 and a first biasing means 13 for biasing said lever in its non-clamping position. The clamp bar 12 has a first surface 18 for contacting a portion of the belt 4. The mounting means 14 may be a channel 20 in the lever 10. The clamp bar 12 is disposed in the channel 20 and is movable with reference to the lever 10. The lever 10 also includes retaining means for retaining the bar 12 in the channel 20. The crest 16 is disposed on a second surface of the bar 12 opposite from the first surface 18 which contacts a portion of the belt 4. The bar 12 is movable on the crest 16 in the channel 20 for applying a substantially uniform force over an area of contact on the belt 4.

The retaining means for retaining the bar 12 in the channel 20 includes: a first lip 22 on a first side of the channel 20 and a second lip 24 on a second opposing side of the channel 20. The clamp apparatus 2 further includes a recess 26 in the bar 12 adjacent to the first lip 22 and a second biasing means, which may be a spring 28, disposed in the recess 26 between the bar 12 and the first lip 22 of the lever 10. The spring 28 biases the bar 12 away from the portion of the belt 4 adjacent to the first surface 18, and prevents the surface 18 from interfering with free movement of the belt 4 when the lever is in its non-clamping position shown in FIGS. 1 and 3. The spring 28 also prevents rattle of the bar 12 within the recess 20.

Referring to FIGS. 1 and 2, the clamp apparatus 2 further includes a pivot means, referred to generally by the numeral 30, for moving the lever 10 and its associated components in a substantially vertical plane and a swivel means, referred to generally by the numeral 32, for moving the lever 10 and its associated components in a substantially horizontal plane. The pivot means 30 includes a first side 38 and a second side 40 disposed parallel to one another in a substantially vertical plane. The first and second sides 38 and 40 form upstanding legs of a U shape. The lever 10 is disposed between the first side 38 and the second side 40 of the first bracket 34. The first shaft 36 is disposed in a substantially horizontal plane and passes through the first and second sides 38 and 40 and through the lever 10. The lever 10 and its associated components pivot on the first shaft 36 through a substantially vertical plane. The first bracket 34 further includes a third side 42 and a fourth side 44 disposed parallel to one another in a substantially horizontal plane. The third and fourth sides 42 and 44 also form upstanding legs of a U shape. The swivel means 32 includes a second U-shaped bracket 46 and second shaft 48. The second bracket 46 has a fifth side 50 and a sixth side 52 disposed parallel to one another in a substantially horizontal plane. The fifth and sixth sides 50 and 52 also form upstanding legs of a U shape. The second shaft 48 is disposed in a substantially vertical plane and passes through the third and fourth sides 42 and 44 of the first bracket 34 and the fifth and sixth sides 50 and 52 of the second bracket. As a result, the first bracket 34, the lever 10 and its associated components swivel on the second shaft 48 through a substantially horizontal plane with respect to the second bracket 46.

Referring to FIGS. 1 and 3-6, the biasing means 13 is a wire spring 54. Referring to FIG. 4, the spring 54 has an elongated portion 56 and two ends. The spring 54 has a hairpin turn 58 at each of its ends and two legs 60 and 62.

Referring to FIG. 7, two resilient bushings 72 are preferably fitted within the lever 10 and around the shaft 36 extending laterally between the first side 38 and the second side 40 of the first bracket 34. The bushings 72 evenly distribute the force applied by the lever 10 laterally across the width of the belt 4 adjacent to surface 18. The bar 12 movable on the crest 16 serves to equalize the force applied by the belt 4 longitudinally along the length of the portion of the belt 4 contacted by the bar 12. The bushings 72 also maintain an approximately constant space between the belt 4 and the bracket 34 and between lever 10 and the belt 4. The bushings 72 also compensate for slight errors in placement of the holes 74 and 76 in the first side 38 and the second side 40 of the first bracket 34 through which the first shaft 36 fits.

In operation, when a force above a predetermined amount is applied in a first direction 6 to the belt 4, it moves the lever 10 from its non-clamping position shown in FIGS. 1 and 3 to its clamping position shown in FIG. 5. Such force above a predetermined amount compresses the legs 60 and 62 of the spring 54 from their position shown in FIG. 4 to their position shown in FIG. 6. The surface 18 of the bar 12 applies a substantially uniform force over an area of contact on a portion of the belt 4 adjacent to the surface 18. Such area contact rather than a line of contact by an edge of the surface 18, or point contact, improves the clamping action on the belt 4. Area contact is obtained by movement of the bar 12 on the creast 16, in conjunction with action of the bushings 72 and in conjunction with pivoting action in two planes on shafts 36 and 48. As a result, the force applied by surface 18 is substantially perpendicular to the plane of the belt 4 adjacent to surface 18. The surface 18 has frictional means, such as knurls, for applying a braking force to the belt 4 to stop movement of the belt 4 through the clamp apparatus 2 in the first unwinding direction 6. A surface 66 on the side of the first bracket 34 facing surface 18 also may have a frictional means, such as knurls, for applying a braking force on the opposite side of the belt 4 to assist in stopping movement of the belt 4 in first unwinding direction 6. In the clamping position of the apparatus 2, shown in FIG. 5, the belt 4 is squeezed between surface 18 and surface 66.

Braking force on the portion of belt 4 between surface 18 and surface 66 is applied by the lever 10 through the crest 16. There are several means for varying the amount of braking force applied to the belt 4. One means is to vary the type of frictional surface on surface 18 and on surface 66. Another means is to vary the leverage applied. The leverage applied is a function of a first distance 68 from the first shaft 36 to the top of the lever 10 where the belt 4 goes around the lever and a second distance 70 from the first shaft 36 to the crest 16. More specifically, the leverage is a function of the ratio of distance 68 to distance 70. Varying the amount of force applied by the lever 10 to the belt 4 between surfaces 18 and 66 may, if desired allow controlled slippage of the belt 4 through the apparatus 2 in an unwinding direction 6.

Referring to FIGS. 8-10, the belt clamp apparatus 2 may be used in an improved safety restraint system 78 for a seated occupant in a vehicle. The restraint system 78 of the present invention includes a shoulder belt means 80 passing over a shoulder of the seated occupant. Typically, the system 78 also includes a lap belt means 82 passing over the lap of the occupant. The belt clamp apparatus 2 is mounted in the vehicle at or above a horizontal plane in the vehicle passing over a shoulder of a seated occupant in the vehicle, such as on a "B-pillar" of the vehicle or on the roof of the vehicle. The belt clamp apparatus 2 of the present invention is responsive to an unwinding force on the belt means 80 above a first predetermined amount, for example, about forty (40) Newtons, resulting from a pull on the shoulder belt means 80 when the seated occupant lurches forward as a result of an emergency condition. The safety restraint system 78 also includes a retractor 84 mounted in the vehicle below the belt clamp apparatus 2 for allowing unwinding of the shoulder belt means 4 in the first direction 6 out of the retractor 84 and for winding the shoulder belt means 80 in the second direction 8 into the retractor 84.

The belt clamp apparatus 2 of the present invention may be used in a variety of ways in the improved safety restraint system 78, such as to provide: a belt sensitive safety restraint system, or a vehicle sensitive safety restraint system, or a dual sensitive safety restraint system, or a force limiting safety restraint system. If a belt sensitive safety restraint system is desired, the retractor 84 may be a simple, inexpensive non-locking retractor. A belt sensitive safety restraint system is a system responsive to force applied on the shoulder belt means 80 in the first direction 6, causing a portion of the belt means 80 to be unwound from the retractor 84. A non-locking retractor allows the shoulder belt means 80 to be freely wound and unwound from the retractor under all conditions. An example of a non-locking retractor is described in U.S. Pat. No. 3,445,078. In such a belt sensitive system having a non-locking retractor, the belt clamp apparatus 2 provides the safety restraint system with belt sensitive capability. The belt clamp apparatus 2 is responsive to an unwinding force on the belt means 80 above the first predetermined amount, for example, about forty (40) Newtons, resulting from a pull on the shoulder belt means 80 when the seated occupant lurches forward as a result of an emergency condition. The belt clamp apparatus 2, in response to such a force above the first predetermined amount, clamps against the belt 4 between surface 18 and surface 16 (FIG. 1), stopping further movement of the belt 4 through the belt clamp apparatus 2 in the first direction 6. Such a non-locking retractor may be simple and inexpensive because it need not have a capacity for withstanding force above the first predetermined amount and because it need not have a locking mechanism, a vehicle sensitive inertial mechanism, or belt sensitive mechanism.

If a vehicle sensitive safety restraint system is desired, the belt clamp apparatus 2 may be used in combination with a vehicle sensitive restractor. A vehicle sensitive safety restraint system is responsive to force applied on the vehicle, such as acceleration, deceleration or change in orientation of the vehicle. The belt clamp apparatus 2 is arranged so that a comparatively high amount of force is required to move the belt clamp apparatus 2 to its clamping position, shown in FIG. 5. This may be arranged, for example, by providing a very strong spring 54. As a result, the vehicle sensitive retractor comes into play during an emergency condition before the belt clamp apparatus 2 can be moved to its clamping position. The vehicle sensitive retractor is responsive to acceleration, deceleration or change in orientation of the vehicle and has a locking mechanism within the retractor which locks the reel of the retractor and prevents further unwinding of the safety belt means 80 from the retractor. Examples of vehicle sensitive retractors are shown in U.S. Pat. Nos. 3,838,831; 3,901,461; 3,913,861; 3,913,862; and 3,940,083.

If a dual sensitive safety restraint system is desired, the belt clamp apparatus 2 may be used in combination with a vehicle sensitive retractor. A dual sensitive safety restraint system is responsive to force applied on the vehicle and is also responsive to force applied on the shoulder belt means 80. The belt clamp apparatus 2 has a comparatively weaker spring 54 than in the vehicle sensitive safety restraint system and provides the restraint system with its belt sensitive capability. The vehicle sensitive retractor provides the safety restraint system 78 with vehicle sensitive capability. Thus, when the occupant lurches forward under emergency conditions and causes a force on the shoulder belt means 80 above the first predetermined amount, for example, about forty (40) Newtons, the belt clamp apparatus 2 clamps against the belt 4 and (FIG. 1) prevents further movement of the belt 4 (FIG. 1) through the belt clamp apparatus 2.

If a force limiting safety restraint system is desired, the safety belt apparatus 2 may be used in conjunction with a belt sensitive retractor. A force limiting safety restraint system is responsive to a force applied on the belt means 80 above a second predetermined amount, for example, about 6000 Newtons, and has a capability for absorbing force above such second predetermined amount, thereby reducing such force above the second predetermined amount to be applied to the occupant. A belt sensitive retractor is a retractor which has a mechanism responsive to acceleration applied on the safety belt means 80. An example of a belt sensitive retractor is described in U.S. Pat. No. 3,741,496. When a force above the first predetermined amount, for example, about 6000 Newtons, is exerted on the shoulder belt means 80, resulting from a pull on the belt means 80 when the occupant lurches forward, the belt clamp apparatus 2 clamps against the belt means 80 and prevents further movement of the belt means 80 through the clamp apparatus until the unwinding force on the belt means 80 reaches a second predetermined amount, for example, about 6000 Newtons, which is greater than the first predetermined value. The belt clamp apparatus 2 has controlled slippage means responsive to unwinding force on the belt means 80 above the second predetermined amount resulting from a pull on the belt means 80 when the occupant lurches forward in response to a force above the second predetermined amount. The belt clamp apparatus 2 allows controlled slippage of the belt means 80 through the belt clamp apparatus 2, thereby absorbing some or all of the force above the second predetermined amount. If the force on the belt means 80 reaches a third predetermined amount, for example, about 7500 Newtons, which is in excess of the second predetermined amount, the belt sensitive mechanism in the retractor comes into play. The belt sensitive mechanism in the retractor locks in response to a force above the third predetermined amount, there by preventing further unwinding of the belt means 80 from the retractor. The third predetermined amount is greater than the second predetermined amount and is also greater than the first predetermined amount. The retractor may be dual sensitive, that is, it may also have a vehicle sensitive mechanism which is responsive to acceleration, deceleration or change in orientation of the vehicle and locks a reel in the retractor to prevent further unwinding of the belt. Examples of dual sensitive retractors are described in U.S. Pat. Nos. 3,858,824 and 3,918,658.

Controlled slippage of the web through the belt clamp apparatus may be achieved by a variety of means. It may be done by changes in design within the belt clamp apparatus, such as the arrangement of the ratio of the first distance 68 to the second distance 70 which varies the leverage of the lever 10 of by varying the frictional braking force applied by clamping surface 18 or surface 66 or both. It may be achieved by changes in an included angle 86 of the belt. The included angle 86 is the angle formed between the shoulder belt means 80 at the top of the clamp apparatus 2 and the shoulder belt means 80 at the bottom of the belt clamp apparatus 2. Preferably, the shoulder belt means 80 at the bottom of the clamp apparatus 2 lies in a substantially vertical plane. If the clamp apparatus 2 is positioned high on the "B-pillar" near the roof as shown in FIGS. 8 and 9, the included angle 86 is smaller than if the clamp apparatus2 is positioned lower on the "B-pillar" closer to the shoulder of the seated occupant as shown in FIG. 10. As the included angle 86 becomes greater, approaching the range of 90.degree.-135.degree., the belt means 80 has more of a tendency to slip through the clamp apparatus 2. Preferably, the included angle 86 is at or less than about 90.degree.. Controlled slippage may also be achieved by changes in the surface frictional characteristics of the belt composition or by a combination of the foregoing means. The force limiting restraint system is reusable because the energy absorbing function is not accomplished by a breakable member or any other type of one-time operation.

The shoulder belt means 80 may further include an inflatable portion 88 and means for inflating it, such as described in U.S. Pat. Nos. 3,841,654; 3,866,940; 3,897,081; 3,888,503; 3,877,719; 3,970,329; 3,929,348; and 3,820,842.

The retractor 84 may be positioned on the floor of the vehicle, as shown in FIGS. 8 and 10, or on a "B-pillar" of the vehicle, as shown in FIG. 9. The restraint system 78 may include a buckle 90 and a tongue 92 for the buckle 90. The tongue 92 may be arranged so that the belt means 80 and 82 slide through a portion of the tongue 92.

The belt clamp apparatus 2 prevents unwinding of the belt means 80 and 82 resulting from "spool down" and resulting from elongation or stretching of the belt. This is particularly important in restraint systems using a comparatively long length of belt means. "Spool down" occurs when a portion of the belt means 80 already wound around a spool or reel inside the retractor 84 is further tightened around the spool by a force in the first direction 6. Even if rotation of the spool is stopped, tightening of belt convolutions around the spool allows a length of belt to be pulled out of the retractor 84. Such "spool down" or elongation would otherwise reduce the ability of the belt means 80 and 82 to restrain an occupant. When the belt clamp apparatus 2 clamps the belt 4, it prevents force in the belt means 80 or 82 from reaching the retractor 84, thereby preventing "spool down" and elongation between the belt clamp apparatus 2 and the retractor 84. Thus, the belt clamp apparatus 2, and the restraint system in which it is used, reduce forward displacement of the occupant during emergency conditions, such as a vehicle crash, and reduce injuries to the occupant.

This invention also provides a method for absorbing unwinding force resulting from a pull on a safety belt means in an occupant restraint system when an occupant lurches forward against the belt means, which method comprises applying a clamping force to a portion of the belt means for resisting movement of the belt means in an unwinding direction, limiting the clamping force to a predetermined amount and allowing the belt means to be unwound against the clamping force in response to an unwinding force above the predetermined amount. In addition, the invention provides, in a vehicle safety restraint system having a belt means for restraining an occupant when the occupant lurches forward against the belt means under emergency conditions, a method for reducing undesired unwinding of the belt means from a retractor in the restraint system after a locking action has been applied to the belt means within the retractor and reducing undesired elongation of the belt means between the retractor and the occupant, comprising applying a clamping force to a portion of the safety belt means between the retractor and the occupant for resisting movement of the safety belt means in an unwinding direction from the retractor.