Load-limiting seat belt retractors

Abstract

A seat belt retractor includes a spool, a piston, a cylinder, a ring, and a valve. The spool is rotatably connected to a base via the piston and the cylinder. The piston is fixed to one of the base and the spool. The cylinder receives the piston and is fixed to the other of the base and the spool. The piston and the cylinder define a first chamber. The ring seals the cylinder and defines a second chamber, which is connected to the first chamber via an orifice. The valve is disposed across the orifice.

Description

Technical Field

[0001] The present disclosure relates to vehicle seat belts, and more particularly to a seat belt assembly having a load-limiting seat belt retractor. Background Art

[0002] The seatbelt portion of a vehicle restraint system protects vehicle occupants from harmful movements that could result from a vehicle collision. Seatbelts can reduce the likelihood of injury by reducing the forces of impact between the occupant and the vehicle's internal structure. In doing so, the seatbelt applies loads to the occupant's chest or legs. Controlling or reducing these loads can reduce the risk of occupant injury during a collision. A seatbelt system may include a retractor that incorporates a load-limiting device. The retractor includes a spool around which the webbing is wound. In the event of a vehicle collision, the spool is locked, preventing it from rotating and the webbing from unwinding. A load-limiting mechanism within the retractor allows for control or reduction of the restraint load transmitted to the occupant during a vehicle collision. Known load-limiting mechanisms include a torsion bar positioned at the center of the spool. The torsion bar may be a cylindrical steel bar with a yield strength selected to allow it torsionally yield at a predetermined value that limits the load transmitted to the occupant, thereby reducing the risk of injury during a vehicle collision. The twisting of the torsion bar absorbs some of the inertial energy, thereby reducing the load on the occupant against the webbing. Torsion bars, when plastically deformed, may yield in a non-linear manner that is difficult to replicate. It would be desirable to provide an improved load limiting mechanism. Summary of the Invention

[0003] The relative orientations and directions recited in this specification (e.g., upper, lower, bottom, forward, rearward, front, rear, back, lateral, lateral, left, right) are not intended to be limiting, but rather to facilitate the reader's understanding of at least one embodiment of the described structure. This exemplary orientation is from the perspective of an occupant seated in a seat, facing the instrument panel. In the drawings, like numbers indicate like parts throughout the several views.

[0004] A seat belt retractor includes a spool, a piston, a cylinder, a ring, and a valve. The spool is rotatably connected to a base via the piston and cylinder. The piston is fixed to one of the base and the spool. The cylinder receives the piston and is fixed to the other of the base and the spool. The piston and cylinder define a first chamber. The ring seals the cylinder and defines a second chamber, which is connected to the first chamber via an orifice. The valve is positioned across the orifice.

[0005] The seat belt retractor may further include a housing and a base lock. The spool is rotatably coupled to the housing to permit rotation relative to the housing about a rotation axis defined by the spool. The base lock may be disposed between the base and the housing. The base lock secures the base to the housing in a first state.

[0006] A seat belt retractor may include a spool, a housing, a base lock, a base, and an energy absorber. The spool may be rotatably connected to the base via the energy absorber. The spool may be rotatably coupled to the housing so as to rotate relative to the housing about an axis of rotation defined by the spool. The base lock may be disposed between the base and the housing. The base lock may secure the base to the housing in a first state. The energy absorber may include a piston, a cylinder, a ring, and a valve. The piston may be secured to one of the base and the spool. The cylinder may receive the piston and may be secured to the other of the base and the spool. The piston and the cylinder together define a first chamber. The ring may seal the cylinder and may define a second chamber, which is connected to the first chamber via an orifice. The valve may be disposed across the orifice.

[0007] The base lock may further include a plurality of clutch teeth and engaging teeth. The plurality of clutch teeth may be disposed on the outer circumference of the base so as to rotate with the base. The engaging teeth may be connected to the housing. In a first state, the engaging teeth engage with the clutch teeth. In a second state, the engaging teeth do not engage with the clutch teeth. The engagement of the engaging teeth with the clutch teeth rotatably secures the cylinder to the base.

[0008] The piston may have piston threads. The cylinder may include a hole for receiving the piston. The cylinder threads may be within the hole. The piston threads and the cylinder threads may be threadedly engaged with each other.

[0009] The cylinder may be connected to the base and the piston may be connected to the spool.

[0010] The ring may be divided into a plurality of sub-chambers, each sub-chamber having an orifice connected to the first chamber and a valve disposed across the orifice.

[0011] The plurality of sub-cavities may be at least three.

[0012] The valve may be a rupturable pressure relief valve having a rupture strength corresponding to a predetermined seat belt tension.

[0013] The valves may be pressure relief valves and may each have a predetermined pressure relief value. The pressure relief value of each pressure relief valve may be selected to correspond to an associated predetermined seat belt tension. The predetermined seat belt tensions are not equal.

[0014] The flow area of ​​the orifice and the pressure relief value of the valve associated with the orifice may be inversely proportional, wherein the flow area of ​​the orifice decreases as the pressure relief value of the valve increases.

[0015] The end cap is rotatably fixed to the reel and fixed to one end of the piston. The end cap can be rotatably supported by a spring cover. BRIEF DESCRIPTION OF THE DRAWINGS

[0016] Figure 1 is a perspective view of a vehicle occupant with an exemplary seat belt system.

[0017] Figure 2 is a first perspective view of an exemplary retractor.

[0018] Figure 3 yes Figure 2 A second perspective view of an exemplary retractor.

[0019] Figure 4 yes Figure 2 and Figure 3 Exploded view of an exemplary retractor.

[0020] Figure 5 yes Figure 4 An enlarged perspective view of an exemplary energy absorber of an exemplary retractor.

[0021] Figure 6 yes Figure 5 A cross-sectional perspective view of an exemplary energy absorber of FIG. 1 , wherein the cross-section is taken through a plane coinciding with the axis of rotation.

[0022] Figure 7 It is a cross-sectional side view of the joint mechanism in a non-collision state.

[0023] Figure 8 yes Figure 7 A cross-sectional side view of the engagement mechanism is shown in a crashed state.

[0024] Figure 9A yes Figure 5 sectional view downwards through the imaginary cutting plane 9 in the direction of arrow 9 ′ of the energy absorber in the first state.

[0025] Figure 9B yes Figure 9A A downward cross-sectional view of the energy absorber in the second state.

[0026] Figure 9C yes Figure 9A A downward cross-sectional view of the energy absorber in the third state.

[0027] Figure 9D yes Figure 9A A downward cross-sectional view of the energy absorber in a fourth state.

[0028] Figure 10 yes Figures 2 to 9D Force versus displacement diagram of the energy absorber. DETAILED DESCRIPTION

[0029] like Figures 1 to 10 As shown, an exemplary restraint system 20 may be provided in a vehicle 22. The vehicle 22 includes a seat 24 that may support an occupant 26 of the vehicle 22. The seat 24 may be a front seat or a rear seat and may be located in any position across the vehicle. Figure 1 The seat 24 shown in FIG is a bucket seat, but alternatively, the seat 24 may be a bench seat or another type of seat. The occupant 26 may be an adult or a teenager, or may alternatively be a child car seat for supporting an infant or toddler. The position and orientation of the seat 24 and its components may be adjusted by the occupant 26.

[0030] The restraint system 20 includes an exemplary seat belt system 28 and may also include an air bag system (not shown). The seat belt system 28 shown is a three-point system. By three-point, it is meant that the seat belt (i.e., webbing or belt) 30 of the system 28 restrains the occupant 26 at three points: at the shoulder (at the Figure 1 In the example, the right shoulder) and on both sides of the passenger's knees.

[0031] In addition to the seat belt 30, the seat belt system 28 may also include a retractor 32, a D-ring 34, a seat belt latch plate 36, an anchor (not shown), a buckle 38, and a buckle mount 40. Alternatively, the seat belt system 28 may include another arrangement of attachment points. The seat belt system 28, when fastened, holds the occupant 26 in the seat 24, such as during a sudden deceleration of the vehicle 22.

[0032] The retractor 32 receives and deploys the first end of the seat belt 30. As shown, the retractor 32 may be secured to the vehicle structure, such as to the B-pillar 42, or alternatively to the frame of the seat 24. Alternative vehicle structure locations include the floor of the vehicle 22.

[0033] The D-ring 34 provides consistent orientation of the seat belt 30 across the shoulders of the occupant, such as at the back of the seat 24. The D-ring 34, when included, receives the seat belt 30 and directs the seat belt 30 from the retractor 32 across the shoulders of the occupant 26. The D-ring 34 can be secured to the back of the seat 24, or alternatively, to a structural member of the vehicle, such as a B-pillar 42. The D-ring 34 can be omitted from the system 28 when the retractor 32 is mounted to one of the B-pillar 42 and the seat frame.

[0034] The seat belt latch plate 36 (i.e., clip) selectively engages a buckle 38 on the inside of the occupant 26. The latch plate 36 is received by a slot in the buckle. The buckle 38 is secured to the vehicle structure or seat frame by a buckle mount 40.

[0035] The seat belt anchor may be in the form of an anchor plate (not shown) and may be disposed on the outside of the seat 24. The plate is secured to a second end of the seat belt 30 opposite the retractor 32 and is also secured to one of the frame of the seat 14 and the structure of the vehicle 12, thereby securing the second end of the seat belt 30.

[0036] The latch plate 36 slides freely along the seat belt 30 and, when engaged with the buckle 38, separates the seat belt 30 into a lap belt 44 and a shoulder belt 46. The lap belt 44 is disposed between the latch plate 36 and the anchor. The shoulder belt 46 can be disposed between the latch plate 36 and the D-ring 34.

[0037] refer to Figures 2 to 10 The exemplary retractor 32 includes a housing 48, a spool 50, a retractor spring 52, a disk 54, a base 56, a base lock 58, a spring cover 60, and a lock cover 61. The spool 50 is rotatably coupled to the housing 48 for rotation relative to the housing 48 about a rotation axis 62 defined by the spool 50. The spool 50 is rotatably connected to the base 56 via an energy absorber 63, i.e., is rotatably fixed for rotation with the base 56.

[0038] A lock cover 61 is secured to the housing 48 at the second end of the spool 50 and is disposed over the base 56 and the lock 58 . Figure 7 and Figure 8 The illustrated lock 58 , best shown in FIG. 5 , may include components secured to the housing 48 or the lock cover 61 .

[0039] The spool 50 can freely rotate relative to the housing 48. A first end of the seat belt 30 is connected to the spool 50. The spool 50 includes a hub 64, which can be cylindrical and centered about an axis 62. The spool 50 can be adapted to receive the seat belt 30, for example, by including a webbing attachment slot 65 and permitting the seat belt 30 to be wound around the hub 64 of the spool 50.

[0040] The seat belt 30 may be attached to the spool 50. Specifically, one end of the seat belt 30 may be attached to the seat belt anchor, and the other end of the seat belt 30 may be attached to the spool 50, where the seat belt 30 is wound around the spool 50 from the other end. The seat belt 30 may be formed of a strip-shaped fabric.

[0041] The spool 50 may include a first spool flange 66 at a first end of the hub 64 and a second spool flange 68 at a second end of the hub 64. The flanges 66, 68 may provide boundaries for the seat belt 30, thereby helping to maintain alignment of the layers or wraps of the seat belt over the hub 64.

[0042] The retractor spring 52 rotatably biases the spool 50 relative to the housing 48. As described above, the retractor spring 52 may extend from the housing 48 to the spool 50 directly or indirectly (e.g., via the disc 54 and the cover 60). When the seat belt 30 is fully retracted, the retractor spring 52 may be loaded into a tensioned or compressed state, and may be further loaded into a tensioned or compressed state as the seat belt 30 extends from the spool 50. Thus, the retractor spring 52 may exert a force tending to retract the seat belt 30. The retractor spring 52 may be a helical torsion spring or any other suitable type of spring. The spring cover 60 is secured to the housing 48 at the first end of the spool 50 (provided by the first spool flange 66) and is positioned above the disc 54 and spring 52. The spring cover 60 may include a support sleeve 70 that receives the spindle portion 71 of the end cap 72 for rotatable support of the spool 50. The end cap 72 may be secured to the spool 50 in any suitable manner (eg, by welding) to ensure integral movement with the spool 50 .

[0043] The housing 48 can be formed from stamped steel or other suitable rigid material (e.g., plastic). The housing 48 can include a center portion 74 connecting a first wing 76 and a second wing 78. The first wing 76 and the second wing 78 are located on opposite sides of the center portion 74 and face each other. The wings 76, 78 receive the spool 50, with the flanges 66, 68 disposed between the wings 76, 78. The housing 48 can be mounted to a structural element of the vehicle 22, for example, to the B-pillar 42 when the seat 24 is a front seat, to the C-pillar (not shown) when the seat 24 is a rear seat, or can be mounted to the seat 24.

[0044] Energy absorber 63 includes a piston 80, a cylinder 82, and a ring 84. Piston 80 is fixed to one of base 56 and spool 50. As described in more detail below, piston 80 is fixed to spool 50 via end cap 72, and cylinder 82 is fixed to the other of base 56 and spool 50. As described in more detail below, cylinder 82 is fixed to base 56.

[0045] Cylinder 82 has a threaded bore 83 that threadably receives piston 80. Cylinder 82, together with piston 80, and more specifically, with closed first end 86 of piston 80, defines a first chamber 88 within bore 83 of cylinder 82. A substantially incompressible liquid 90 is disposed in first chamber 88. Liquid 90 can fill chamber 88. With the piston 80 and cylinder 82 threadedly engaged, rotation of the piston 80 and cylinder 82 displaces the piston 80 into the cylinder 82, thereby compressing the liquid 90 therein.

[0046] Ring 84 surrounds and is secured to cylinder 82. Ring 84 defines a second cavity 92 relative to cylinder 82, collectively designated by reference numerals 92A, 92B, and 92C. The structure of energy absorber 63 and its operation are described in greater detail below.

[0047] As described above, the spool 50 is rotatably coupled to the housing 48 for rotation relative to the housing 48. The piston 80 is secured to the end cap 72 on the second end 94 for rotation therewith. The end cap 72 may be rotatably secured to the second end 94 by axially oriented external splines 96 on the second end 94, which may be received by complementary internal splines 98 formed on the interior of the end cap 72.

[0048] First spool flange 66 may include flange aperture 100 having splines (not shown) complementary to external splines 96 to facilitate integral rotation of spool 50, end cap 72, and piston 80. An exemplary disc 54 may be secured to first spool flange 66 for rotation with spool 50.

[0049] The first end 86 of the piston 80 has threads 102, also known as piston threads. The second end 94 is threaded into the first end 104 of the cylinder 82. The first end 104 of the cylinder 82 has receiving threads 106, also known as cylinder threads, inside the threaded bore 83 that are complementary to the threads 102. The piston threads 102 are threadedly engaged with the cylinder threads 106. The shank 107 of the piston 80 between the threads 102 and the second end 94 can have an outer diameter equal to or smaller than the minor diameter of the threads 102, allowing the piston 80 to be screwed deeper into the cylinder bore 83 than the threads 102. Alternatively, the threads 102 can extend the entire length of the piston 80 or extend to the external splines 96.

[0050] Flow control orifices 108 (collectively, each of flow control orifices 108A, 108B, and 108C, and indicated thereby in the figures) may extend through a wall 109 of the cylinder 82, thereby connecting the first chamber 88 and the second chamber 92. Rupturable pressure relief valves 110 (collectively, each of rupturable pressure relief valves 110A, 110B, and 110C, and indicated by reference numerals 110A, 110B, and 110C in the figures) are disposed across the flow control orifices 108, thereby preventing the liquid 90 from moving from the first chamber 88 to the second chamber 92.

[0051] Rupturable valve 110 has a rupture strength at a first predetermined pressure P1, corresponding to a force F1 at a given piston area and an associated predetermined seat belt tension. The exact nature of the valve may vary. An exemplary valve is shown in U.S. Patent No. 3,007,773. Alternatively, valve 110 may be in the form of a diaphragm configured to rupture at a predetermined pressure.

[0052] When valve 110 ruptures, liquid 90 can flow from first chamber 88 into second chamber 92. The flow rate of liquid 90 from first chamber 88 to second chamber 92 corresponds to the axial velocity of piston 80 within chamber 88 and the displacement rate of seat belt 30 from spool 50. When piston 80 is driven against the liquid, the size (i.e., flow area) of orifice 108 can affect the pressure of liquid 90 within first chamber 88, thereby controlling the resistance to displacement of piston 80 within bore 83. Thus, the reaction force of liquid 90 on piston 80 varies with the displacement rate of piston 80 and the size (i.e., flow area) of flow control orifice 108. The reaction force can be adjusted to achieve the desired cushioning of seat belt 30 against occupant 26. By varying system parameters related to achieving the desired seat belt reaction force (including thread pitch and size of flow control orifice 108), the maximum force and the desired rate of force increase can be adjusted.

[0053] Second chamber 92 may include a plurality of secondary chambers, i.e., sub-chambers, such as first sub-chamber 92A, second sub-chamber 92B, and third sub-chamber 92C, radially distributed around and extending from cylinder barrel 82. Three barrier walls 111A, 111B, and 111C may be used to separate sub-chambers 92A, 92B, and 92C. Walls 111A, 111B, and 111C may be disposed within and form a portion of ring 84. These walls seal against the inner surface of ring 84 and against cylinder barrel 82.

[0054] Secondary chambers 92A, 92B, and 92C may be connected to first chamber 88 via specially sized first, second, and third flow control orifices 108A, 108B, and 108C through cylinder wall 109. Each of orifices 108A, 108B, and 108C may have a unique size, i.e., flow area.

[0055] Orifices 108A, 108B, and 108C may be covered by first, second, and third valves 110A, 110B, and 110C, respectively, each valve having a unique predetermined relief value (corresponding to belt tension) selected for use with the associated sub-chamber 92A, 92B, and 92C.

[0056] As described in more detail below, providing the three secondary chambers 92A, 92B, and 92C with unique orifice sizes and unique valve rupture values ​​allows for a step-wise increase in load loading in response to seat belt forces when the spool is locked. Alternatively, for alternative adaptation requirements, all three flow control orifices 108A, 108B, and 108C can be connected to a single, common second chamber 92, since the second chamber 92 can be provided by the ring 84 without the need for walls 111A, 111B, and 111C. The second end 94 can also form a side of the ring 84.

[0057] The base 56 can be in the form of a circular disc. The cylinder 82 is fixed to the base 56 at the second end 112 for rotation therewith. The second end 112 can be rotatably fixed to the base 56 by axially oriented external splines 114 on the second end 112, which can be received by complementary internal splines 116 formed within an aperture 118 in the base 56.

[0058] The base lock 58 can be any mechanism suitable for preventing or limiting rotation of the base 56 or spool 50 relative to the housing 48. Mechanisms such as the lock 58 are known and commercially available from companies including Autoliv Inc. and ZF Friedrichshafen AG. One type of base lock can engage the cylinder 82 with the housing 48 in response to rapid movement of the webbing 30 and the associated rapid spinning of the spool 50. Another type of base lock, consistent with the illustrated base lock 58, can engage the base 56 with the housing 48 in response to sudden deceleration or rearward acceleration of the vehicle 22. Combining both types of mechanisms into a single retractor 32 is also known. The exemplary base lock 58 is merely one method of engaging the base 56 with the housing 48. The exemplary base lock 58 includes axially extending clutch teeth 120 disposed around the outer circumference of the base 56 and engages the clutch teeth 120 under predetermined conditions.

[0059] The base lock 58 can include a pivot arm 124 that is pivotable relative to a ball retainer 126. The ball retainer 126 includes a first ball track 128, and the ball retainer 126 is fixed relative to the housing 48. The pivot arm 124 includes a second ball track 130 facing the first ball track 128. The pivot arm 124 also includes engaging teeth 132 on a side opposite the second ball track 130. The teeth 132 are connected to the housing 48 via the pivot arm 124. In the installed position, the tracks 128, 130 are parallel to the forward movement direction of the vehicle 22. Balls 134 (e.g., steel balls) are disposed in the tracks 128, 130. A hinge 136 is located behind the tracks 128, 130, which allows pivotal movement of the pivot arm 124 relative to the ball retainer 126.

[0060] In the first position, the tooth 132 and the pivot arm 124 are pivoted downwardly, thereby ensuring that there is no engagement between the tooth 132 and the clutch tooth 120. Also in the first position, associated with the rearward position of the ball 134 on the tracks 128, 130, as shown in FIG. Figure 7 As shown, the distance between the front ends of the tracks 128, 130 is less than the diameter of the ball 134. The unwinding rotation direction of the spool 50 is indicated by arrow 138. Rotation of the spool 50 in the direction of arrow 138 causes the webbing 30 to unwind from the spool 50 and be released from the retractor 32.

[0061] In the second position, the tooth 132 and pivot arm 124 are pivoted upward toward the base 56 and the tooth 132 is engaged with the clutch tooth 120. In the second position, associated with the forward position of the ball 134 on the tracks 128, 130, as shown in FIG. Figure 8 As shown, the distance between the front ends of the rails 128, 130 is greater than the distance in the first position.

[0062] A pivot spring 140 may be provided between the pivot arm 124 and the ball retainer 126 to bias the pivot arm 124 toward the disengaged position (ie, unlocked state). Biasing the pivot arm 124 downward may also bias the ball 134 to the disengaged position.

[0063] The second ball track 130 has a first portion in a first position relatively close to the hinge 136. With the base lock 58 in the locked state, ie, with the engagement teeth 132 of the pivot arm 124 engaged with the clutch teeth 120, the base 56 is fixed relative to the housing 48.

[0064] The seat belt retractor 32 operates as follows, and as Figure 10 and 9A to 9D shown. 9A to 9D It is a cross section taken along the direction of arrow 9 ′ through the intersection of the energy absorber 63 and the imaginary plane 9 .

[0065] Figure 10 Graph 142 is a graph 144A depicting an example relationship between the displacement of the seat belt 30 from the reel 50 in the unwinding direction 138 and the seat belt force resisted by the energy absorber 63. The horizontal axis is labeled "Displacement (Belt Pull-Out Length)" but could alternatively be labeled "Spool Rotation" or "Piston Displacement" because a substantially linear relationship exists between all three values. The vertical axis is labeled "Belt Force" but could alternatively be labeled "Spool Torque" or "Piston Pressure" because a substantially linear relationship exists between all three values.

[0066] In the event of a frontal collision, the occupant 26 of the front seat 24 has forward momentum relative to the rest of the vehicle 22. Similarly, the ball 134 of the base lock 58 has forward momentum relative to the ball retainer 126 and the pivot arm 124. The associated forward movement of the ball 134 along the tracks 128, 130 causes the pivot arm 124 to overcome the torque of the pivot spring 140 and pivotally displace away from the retainer 126. The pivoting of the pivot arm 124 causes the engaging teeth 132 to engage the clutch teeth 120 of the base 56, thereby preventing further rotation of the cylinder 82 relative to the housing 48.

[0067] The forward inertial movement of the occupant 26, particularly the upper torso of the occupant 26, can act on the webbing 30. Since the engagement of the teeth 132 with the teeth 120 prevents rotation of the base 56, the occupant's inertial force on the webbing 30, particularly the shoulder straps 46, is resisted by the reel 50 of the retractor 32.

[0068] and Figures 2 to 9D Consistent with the embodiment of the present invention, when the spool 50 resists a predetermined amount of passenger inertia, the prevention of rotation of the base 56 does not immediately prevent the spool 50 from rotating and further deploying the webbing 30 from the retractor 32. When the base 56 is locked, rotation of the spool 50 rotates the piston 80 relative to the cylinder 82, thereby screwing the piston 80 deeper into the cylinder 82.

[0069] Graph 142 is consistent with the description of the operation of system 20 and its associated graphs 144A, 144B, and 144C. The stepped appearance of baseline graph 144A, associated with the first velocity (i.e., the velocity of piston 80 in the axial direction), is explained by the sequential transfer of liquid 90 from first chamber 88 to secondary chambers 92A, 92B, and 92C. Each secondary chamber 92A, 92B, and 92C is connected to first chamber 88 via an associated orifice 108A, 108B, and 108C, with flow initially restricted by valves 110A, 110B, and 110C. Each secondary chamber 92A, 92B, and 92C has a finite volume, e.g., one-third of the available volume of liquid 90 in the unstressed first chamber 88, and each orifice 108A, 108B, and 108C is sealed with its associated rupturable valve 110A, 110B, and 110C, respectively.

[0070] Valves 110A, 110B, and 110C are configured (i.e., formed from selected materials into predetermined shapes) to rupture under gradually increasing pressure / piston force. For example, valve 110A for first sub-chamber 92A may be designed to rupture at a first predetermined seatbelt tension F1, valve 110B for second sub-chamber 92B may rupture at a second predetermined seatbelt tension F2, and valve 110C for third sub-chamber 92C may rupture at a third predetermined seatbelt tension F3, where F3 > F2 > F1. For example, F3 may be three times the value of F1, and F2 may be twice the value of F1.

[0071] Following an exemplary first or baseline curve 144A, the seat belt tension (i.e., seat belt force) associated with the pressure within the first chamber 88 increases from a starting point of zero as the initial displacement of the seat belt 30 and piston 80 increases from a starting point (i.e., zero). This initial, sharp increase in force with very little increase in displacement is due to the compression of the liquid 90 in the first chamber 88 before the first valve 110A ruptures (i.e., opens) at F1. The slope is generally a function of the elastic modulus of the liquid 90. As the liquid 90 flows through the ruptured valve 110A (not shown in its ruptured state), through the first flow control orifice 108A, and into the first secondary chamber 92A, the belt force substantially stabilizes at a value of F1 at the first piston displacement rate.

[0072] When the first sub-chamber 92A is filled at V1, the belt force increases again rapidly until the second valve 110B ruptures at the belt force F2. The second flow control orifice 108B leading to the second sub-chamber 92B is more restrictive than the first flow control orifice 108A connecting the second sub-chamber 92B to the first chamber 88, resulting in a force-to-displacement slope corresponding to the liquid 90 entering the second sub-chamber 92B that is greater than the slope associated with the liquid 90 entering the first sub-chamber 92A. As a result, the flow area of ​​the orifice 108A can be larger than the flow area of ​​the orifice 108B.

[0073] When the second sub-chamber 92B is filled, at line V2, the force resumes its rapid rise, further compressing the liquid 90 in the first chamber 88 until the valve 110C across the orifice 108C for the third sub-chamber 92C ruptures. Because the orifice 108C leading to the third sub-chamber 92C is more restrictive than the orifice 108B leading to the second sub-chamber 92B, the slope of the force associated with the liquid 90 entering the third sub-chamber 92C as a function of displacement is steeper than the slope associated with the liquid 90 entering the second sub-chamber 92B. Consequently, the flow area of ​​the orifice 108B can be larger than the flow area of ​​the orifice 108C. Once the third sub-chamber 92C is filled, the slope increases rapidly because the liquid 90 remaining at the bottom of the first chamber 88 has nowhere to go.

[0074] For systems 20 employing multiple secondary chambers 92 , the flow area of ​​an orifice 108 and the pressure relief value of a valve 110 associated with the orifice 108 may be inversely proportional, wherein the flow area of ​​the orifice 108 decreases as the pressure relief value of the valve 110 increases.

[0075] 108A, 108B, 108C. The force-displacement relationship of the piston 80 and the belt 30 is shown in FIG. 108B. The force-displacement relationship of the piston 80 and the belt 30 is shown in FIG. 108C. The force-displacement relationship of the piston 80 and the belt 30 is shown in FIG. 108B. The force-displacement relationship of the piston 80 and the belt 30 is shown in FIG. 108C. The force-displacement relationship of the piston 80 and the belt 30 is shown in FIG. 108A, 108B, 108C. The force-displacement relationship of the piston 80 and the belt 30 is shown in FIG. 108A, 108B, 108C. The force-displacement relationship of the piston 80 and the belt 30 is shown in FIG. 108A, 108B, 108C. The force-displacement relationship of the piston 80 and the belt 30 is shown in FIG. 108A, 108B, 108C. The force-displacement relationship of the piston 80 and the belt 30 is shown in FIG.

[0076] The additional webbing 30 deployed from the spool 50 by the retractor 32 may correspond to substantially two turns of webbing around the spool 50 after the teeth 132 engage the teeth 120 , for example, approximately 8 to 10 inches.

[0077] The amount of rotation available, and thus the amount of webbing 30 pullout, can be controlled by factors including the inertial energy of the restrained occupant 26, the pitch of the threads 102, 106, and the amount of travel available for the piston 80 to the base 56. The travel of the piston 80 to the base 56 can, in turn, be affected by additional factors including the depth of the bore 83 and the geometry of the ring 84, which determines the available volume of the secondary chambers 92A, 92B, and 92C.

[0078] When the torque required by the ring 84 to transfer the additional fluid 90 from the first chamber 88 to the second chambers 92A, 92B, 92C exceeds the torque generated by the seat belt force, rotation of the spool 50 substantially ceases. Some of the occupant's forward inertial energy is absorbed by the displacement of the fluid 90, thereby reducing the force exerted by the webbing 30 on the occupant 26 when the webbing 30 stops during an incident such as a frontal collision.

[0079] Following a collision in which the valve 110A, 110B, 110C of the energy absorber ruptures, the retractor 32 may be replaced with a replacement retractor 32 .

[0080] The adverb "substantially" as used herein means that shape, structure, measurement results, quantity, time, etc. may deviate from the precisely described geometry, distance, measurement results, quantity, time, etc. due to defects in materials, processing, manufacturing, data transmission, computing speed, etc.

[0081] The present disclosure has been described in an illustrative manner, and it is to be understood that the terminology which has been used is intended to be in the nature of words of description rather than of limitation. Many modifications and variations of the present disclosure are possible in light of the above teachings, and the present disclosure may be practiced otherwise than as specifically described.

[0082] According to the present invention, a seat belt retractor is provided, comprising: a spool rotatably connected to a base via a piston and a cylinder; a piston fixed to one of the base and the spool; a cylinder receiving the piston, fixed to the other of the base and the spool, defining a first chamber; a ring sealing the cylinder and defining a second chamber connected to the first chamber via an orifice; and a valve disposed across the orifice.

[0083] According to one embodiment, the above invention is also characterized by a housing, wherein the reel is rotatably connected to the housing so that the reel rotates relative to the housing around a rotation axis defined by the reel; and a base lock arranged between the base and the housing, the base lock fixing the base to the housing in a first state.

[0084] According to one embodiment, the above invention is also characterized by a plurality of clutch teeth, which are arranged on the outer circumference of the base so as to rotate with the base; and engaging teeth connected to the housing, which engage with the clutch teeth in a first state and do not engage with the clutch teeth in a second state, wherein the engagement of the engaging teeth with the clutch teeth rotatably fixes the cylinder to the base.

[0085] According to one embodiment, the piston has a piston thread, and the cylinder includes a bore to receive the piston, and the cylinder thread is inside the bore, and the piston thread and the cylinder thread are threadably engaged with each other.

[0086] According to one embodiment, the cylinder is connected to the base and the piston is connected to the spool.

[0087] According to one embodiment, the ring is divided into a plurality of sub-chambers, each sub-chamber having an orifice connected to the first chamber and a valve arranged across the orifice.

[0088] According to one embodiment, the plurality of sub-cavities is at least three.

[0089] According to one embodiment, the valve is a rupturable pressure relief valve having a rupture strength corresponding to a predetermined seat belt tension.

[0090] According to one embodiment, the valves are pressure relief valves and each valve has a predetermined pressure relief value, wherein its pressure relief value is selected to correspond to an associated predetermined seat belt tension, and the predetermined seat belt tensions are not equal.

[0091] According to one embodiment, the flow area of ​​the orifice is inversely proportional to the pressure relief value of the valve associated with the orifice, wherein the flow area of ​​the orifice decreases as the pressure relief value of the valve increases.

[0092] According to the present invention, a seat belt retractor is provided, which has a seat belt retractor comprising: a spool rotatably connected to a base via an energy absorber; a housing, wherein the spool is rotatably coupled to the housing so as to rotate the spool relative to the housing around a rotation axis defined by the spool; and a base lock arranged between the base and the housing, the base lock fixing the base to the housing in a first state; and the energy absorber includes: a piston fixed to one of the base and the spool; a cylinder receiving the piston and fixed to the other of the base and the spool and defining a first chamber; and a ring sealing the cylinder and defining a second chamber, the second chamber being connected to the first chamber via an orifice; and a valve arranged across the orifice.

[0093] According to one embodiment, the base lock includes a plurality of clutch teeth, which are arranged on the outer circumference of the base so as to rotate with the base; and engaging teeth connected to the housing, which engage with the clutch teeth in a first state and do not engage with the clutch teeth in a second state, wherein the engagement of the engaging teeth with the clutch teeth rotatably fixes the cylinder to the base.

[0094] According to one embodiment, the piston has a piston thread, and the cylinder includes a bore to receive the piston, and the cylinder thread is inside the bore, and the piston thread and the cylinder thread are threadably engaged with each other.

[0095] According to one embodiment, the ring is divided into a plurality of sub-chambers, each sub-chamber having an orifice connected to the first chamber and a valve arranged across the orifice.

[0096] According to one embodiment, the plurality of sub-cavities is at least three.

[0097] According to one embodiment, the valve is a rupturable pressure relief valve having a rupture strength corresponding to a predetermined seat belt tension.

[0098] According to one embodiment, the valves are pressure relief valves and each valve has a predetermined pressure relief value, wherein its pressure relief value is selected to correspond to an associated predetermined seat belt tension, and the predetermined seat belt tensions are not equal.

[0099] According to one embodiment, the flow area of ​​the orifice is inversely proportional to the pressure relief value of the valve associated with the orifice, wherein the flow area of ​​the orifice decreases as the pressure relief value of the valve increases.

[0100] According to one embodiment, the cylinder is connected to the base and the piston is connected to the spool.

[0101] According to one embodiment, the end cap is rotatably fixed to the spool and to one end of the piston, and the end cap is rotatably supported by the spring cover.

Claims

1. A seat belt retractor, comprising: a reel rotatably connected to the base via a piston and a cylinder; a housing, wherein the spool is rotatably coupled to the housing; a base lock provided between the base and the housing, the base lock fixing the base to the housing in a first state, the base lock comprising: a plurality of clutch teeth provided on an outer circumference of the base so as to rotate together with the base; and engaging teeth connected to the housing, the engaging teeth engaging with the clutch teeth in the first state and not engaging with the clutch teeth in a second state; a piston secured to one of the base and the spool; a cylinder receiving the piston, fixed to the other of the base and the spool, defining a first chamber; and a ring that seals the cylinder and defines a second chamber connected to the first chamber through an orifice; and A valve is disposed across the orifice. 2 . The seat belt retractor according to claim 1 , wherein the valve is a rupturable pressure relief valve having a rupture strength corresponding to a predetermined seat belt tension. 3 . The seat belt retractor of claim 1 , wherein the valve is a pressure relief valve and has a predetermined pressure relief value, wherein the pressure relief value thereof corresponds to an associated predetermined seat belt tension.

4. The seat belt retractor of claim 1, wherein the spool rotates relative to the housing about an axis of rotation defined by the spool.

5. The seat belt retractor according to claim 4, The engagement of the engaging teeth with the clutch teeth rotatably fixes the cylinder to the base. 6 . The seat belt retractor of claim 1 , wherein the piston has piston threads, and the cylinder includes a hole receiving the piston, and the cylinder threads are inside the hole, and the piston threads and the cylinder threads are threadedly engaged with each other. 7 . The seat belt retractor of claim 6 , wherein the cylinder is connected to the base, and the piston is connected to the spool. 8 . The seat belt retractor of claim 1 , wherein the cylinder is connected to the base, and the piston is connected to the spool. 9 . The seat belt retractor according to claim 8 , wherein an end cap is rotatably fixed to the spool and to one end of the piston, and the end cap is rotatably supported by a spring cover.

10. The seat belt retractor according to claim 1 or claim 6, wherein the ring is divided into a plurality of sub-chambers, each sub-chamber having an orifice connected to the first chamber and a valve provided across the orifice. 11 . The seat belt retractor of claim 10 , wherein the piston has piston threads, and the cylinder includes a hole receiving the piston, and the cylinder threads are inside the hole, and the piston threads and the cylinder threads are threadably engaged with each other. 12 . The seat belt retractor according to claim 10 , wherein the plurality of sub-cavities is at least three.

13. The seat belt retractor of claim 10, wherein the valve is a rupturable pressure relief valve having a rupture strength corresponding to a predetermined seat belt tension.

14. The seat belt retractor of claim 10, wherein the valves are pressure relief valves and each valve has a predetermined pressure relief value, wherein its pressure relief value is selected to correspond to an associated predetermined seat belt tension, and wherein the predetermined seat belt tensions are unequal. 15 . The seat belt retractor of claim 14 , wherein a flow area of ​​the orifice is inversely proportional to the relief value of the valve associated with the orifice, wherein the flow area of ​​the orifice decreases as the relief value of the valve increases.

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