Fluid damper to adjust the seat belt retention force

Abstract

To relate to a fluid damper for modulating a retaining force of a seat belt.SOLUTION: A fluid damper comprises an outer cylinder, and an inner cylinder in the outer cylinder. The inner cylinder encloses an internal space. The fluid damper comprises a piston shiftable n the internal space along a longitudinal axis of the cylinder The fluid damper comprises a duct. The duct conductively connects a front fluid chamber of a damping fluid disposed in front of the piston along the longitudinal axis to a rear fluid chamber disposed behind the piston along the longitudinal axis and / or a reservoir for the damping fluid. The duct comprises an outer duct portion in a shell wall of the outer cylinder, and an inner duct portion in a shell wall of the inner cylinder. The inner cylinder is deflectable relative to the outer cylinder from a rest position by a force acting on the piston the longitudinal axis so that this deflection causes an adjustment of an overlap of the outer duct portion and the inner duct portion is adjusted according to a magnitude of the force.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a fluid damper for adjusting the holding force of a seat belt. The fluid damper includes an outer cylinder and an inner cylinder coaxially disposed within the outer cylinder with respect to a common longitudinal axis. The inner cylinder surrounds an internal space filled with damping fluid. The fluid damper includes a piston shiftable along the longitudinal axis within the internal space by a stroke length. The fluid damper includes at least one duct, and the at least one duct conductively connects a front fluid chamber disposed in front of the piston along the longitudinal axis, a rear fluid chamber disposed behind the piston along the longitudinal axis, and / or a reservoir of damping fluid disposed outside the internal space for the damping fluid.

[0002] The present invention further relates to a belt force limiter including the fluid damper.

Background Art

[0003] In modern vehicles, various safety systems are effective in protecting passengers during a collision. Among them are, for example, a seat belt tensioner, an airbag, or a belt force limiter. Here, first, the seat belt tensioner ensures that a belt that may be too loose is applied to the passenger with an initial tension. In order to protect around the passenger's shoulders and at the same time make the most of the effect of the airbag, the belt force limiter ensures that the passenger's head does not intentionally hit the airbag after a specific time and a specific distance, and by limiting the holding force of the belt that holds the passenger, does not exceed the critical load on the shoulders.

[0004] Here, because the known systems do not respond to different occupant weights, or only respond to different occupant weights under the influence of additional sensor systems, the holding force is not optimally adapted to the occupant weight or the vehicle's impact velocity. Consequently, a heavier occupant may not be adequately decelerated before hitting the airbag at high impact velocities due to insufficient holding force, or a lighter occupant may be pulled back by excessive holding force around the shoulders at low impact velocities. In both cases, serious injury may result.

[0005] Patent application DE10113502A1 describes a belt retractor equipped with a hydraulic belt force limiter. For example, the spindle of the belt retractor moves a nut having a throttle hole through a cavity filled with hydraulic fluid. By using a hydraulic force limiter, according to DE10113502A1, the seat belt unwinding length is independent of the vehicle's impact velocity. However, DE10113502A1 does not solve the problem that the unwinding length depends on the mass of a fixed person.

[0006] Patent application DE102012004603A1 describes a belt reel equipped with a force limiter that includes a displacement member that moves with granular material. According to DE102012004603A1, the use of granular material has the effect that as the seat belt extension speed increases, the resistance generated by the force limiter increases, thereby ensuring that the same forward displacement is obtained regardless of the mass of the person being held.

[0007] Utility model DE29880147U1 describes a vehicle occupant holding system that automatically adapts a load limit to the mass of a held person by adapting the holding force to vary according to the person's displacement. For this purpose, the holding system comprises a piston-cylinder means, for example, a cylinder having shearable or compressible inner ribs that increase in width along the cylinder. Thereafter, the ribs generate increasing resistance to movement along the cylinder relative to the piston. Thus, a lighter person will shift the piston only slightly, and therefore will experience less holding force than a heavier person. However, a disadvantage of this concept is that the stroke of the piston-cylinder means is not used optimally, and the high maximum holding force progresses unevenly.

[0008] Known systems for adapting holding force offer only limited adaptation to the occupant's mass, have complex configurations, and / or fail to ensure that the occupant is smoothly decelerated along the available braking distance between the seat and the airbag, thus creating a load peak on the occupant, which can lead to injury. [Overview of the project] [Problems that the invention aims to solve]

[0009] The object of the present invention is to provide a device that is as cost-effective as possible, has a simple design, a long lifespan, and enables the seat belt to decelerate the occupant in accordance with the occupant's weight and / or the vehicle's impact speed. [Means for solving the problem]

[0010] The subject matter of the present invention is to provide a fluid damper according to claim 1 that solves a technical objective. Similarly, the objective is solved by a belt force limiter according to claim 13. Advantageous embodiments are provided by dependent claims.

[0011] The fluid damper according to the present invention is designed to adjust the holding force of a seat belt. The fluid damper may also be used for other applications, for example, as a self-adjusting stop damper, in which the damping force automatically adapts to the impact energy of an object colliding with the stop damper, such as a vehicle flap.

[0012] The fluid damper comprises an outer cylinder and an inner cylinder located coaxially with respect to a common longitudinal axis within the outer cylinder, the inner cylinder having an internal space filled with damping fluid. Both the outer and inner cylinders form the cylinders of the fluid damper. The damping fluid is, for example, a damping liquid, particularly a hydraulic fluid. The outer and inner cylinders preferably each have the form of substantially hollow cylinders.

[0013] The fluid damper includes a piston that can be shifted along the longitudinal axis within the internal space, particularly from the rear end of the stroke length to the front end of the stroke length, and preferably in the reverse direction. The piston is preferably rotationally symmetric with respect to the longitudinal axis.

[0014] The piston is fixed to a piston rod, for example, which is drawn along the longitudinal axis from the outer and inner cylinders. The piston rod and the outer and / or inner cylinders may have coupling elements that connect the piston rod to a seat belt and the cylinder to a vehicle seat or chassis, or vice versa. In this way, the piston can be shifted along the stroke length in the internal space by the movement of pulling the seat belt relative to the seat or chassis. Here, the pulling movement is damped by the damping force of a fluid damper.

[0015] The fluid damper comprises at least one duct, which conductively connects a front fluid chamber located in front of the piston along the longitudinal axis to a rear fluid chamber located behind the piston along the longitudinal axis, and / or a reservoir of damping fluid located outside the internal space, for the damping fluid. In the former case, at least one duct of the damping fluid forms a bypass through which the damping fluid can flow around the piston from the front fluid chamber to the rear fluid chamber and vice versa.

[0016] Preferably, the piston divides its internal space into a front fluid chamber located in front of the piston along the longitudinal axis and a rear fluid chamber located behind the piston along the longitudinal axis, in a manner that particularly seals the damping fluid.

[0017] If the duct conductively connects the front fluid chamber of the damped fluid to a reservoir located outside the internal space, the piston may be configured such that, for example, only a front fluid chamber exists in front of the piston along the longitudinal axis, and there is no rear fluid chamber behind the piston along the longitudinal axis. In this embodiment, the internal space may be completely blocked, for example, by the piston and / or the piston rod on the side of the piston opposite to the front fluid chamber along the longitudinal axis.

[0018] As the piston shifts along its stroke length due to the seatbelt-pulling motion, the damping fluid flows through at least one duct from the front fluid chamber to the rear fluid chamber and / or into the reservoir, or vice versa. Thus, the damping force used to dampen the motion pulled out by the fluid damper is substantially determined by the flow resistance reacting to the flow of damping fluid through at least one duct.

[0019] At least one duct preferably comprises an outer duct portion within an outer cylinder and an inner duct portion within an inner cylinder. The inner and outer duct portions overlap along the shell surfaces of the outer and inner cylinders so that the inner duct portion interacts with the outer duct portion as a duct for damping fluid. The overlap of the duct portions at the interface between the inner and outer duct portions is called the duct portion overlap.

[0020] The outer shell surface of the inner cylinder preferably contacts the inner shell surface of the outer cylinder to seal the damping fluid. This means that the inner cylinder is positioned inside the outer cylinder so that the damping fluid cannot pass between the inner and outer cylinders.

[0021] The inner cylinder is preferably deflectable relative to the outer cylinder from a stationary position by a force acting on the piston along the longitudinal axis, and the deflection of the inner cylinder adjusts the overlap of the outer and inner duct portions along the shell surface according to the magnitude of the force. The deflection may be linear deflection along the longitudinal axis and / or rotational deflection about the longitudinal axis. The inner cylinder and / or outer cylinder may move relative to the fluid damper environment due to the deflection. Because the fluid damper has a structurally simple design, preferably only the inner cylinder moves relative to the periphery.

[0022] As the overlap of the duct sections decreases, the flow resistance of the damping fluid passing through the duct and the resulting damping force of the fluid damper increase. Therefore, the damping force of the fluid damper is automatically adjusted according to the magnitude of the force acting on the piston by the deflection of the inner cylinder.

[0023] The overlap may be maximum at the rest position, for example when there is no force acting on the piston or only a small force is acting, and may decrease when the inner cylinder is deflected from the rest position by an increasing force. In this embodiment, the damping force of the fluid damper is automatically increased by the force acting on the piston, and the force on the piston is increased by the deflection of the inner cylinder. This means that when an occupant applies a large force to the seat belt, and thus a large force is applied to the piston due to the large mass of that occupant or due to a high impact speed, the occupant is pulled back with a greater damping force than in the case of an occupant with a lighter weight or an accident with a slower impact speed. The damping force thus automatically adapts to the mass and impact speed of the occupant, and on the one hand can keep the load applied to the occupant by the seat belt as low as possible, and on the other hand the holding force is large enough so that the occupant does not hit the airbag with excessive kinetic energy.

[0024] The inner cylinder is preferably linearly deflectable along the longitudinal axis by the force acting on the piston along the longitudinal axis, and the linear deflection of the inner cylinder adjusts the overlap of the outer duct portion and the inner duct portion along the shell surface according to the magnitude of the force.

[0025] When the force acting along the longitudinal axis deflects the inner cylinder along the longitudinal axis, this is advantageous in that the fluid damper can have a particularly simple design since there is no need to redirect the force in another direction.

[0026] The maximum deflection of the inner cylinder is preferably substantially smaller than the length of the stroke length, so that the draw length of the seat belt does not substantially change due to the deflection.

[0027] The fluid damper preferably comprises a spring element. For example, the spring element includes a helical compression spring.

[0028] The spring element counteracts the deflection of the inner cylinder relative to the outer cylinder from the rest position. The spring force and / or spring characteristics of the spring element thus determine the interrelationship between the magnitude of the force acting on the piston and the deflection of the inner cylinder, i.e., the damping force of the fluid damper. By selecting an appropriate spring element, it is thus possible to adjust how the damping force of the fluid damper responds to the force acting on the piston. In embodiments that are otherwise identical, the fluid damper can thus be adapted in a simple manner to different requirements by replacing the spring element.

[0029] The spring element preferably biases the inner cylinder towards the rest position relative to the outer cylinder, particularly along the longitudinal axis. By this biasing, it is ensured that the inner cylinder is not inadvertently deflected even by small forces that may lead to malfunction of the fluid damper.

[0030] The inner cylinder is preferably movable relative to the outer cylinder by a shift of the piston along the longitudinal axis, for example, linearly movable along the longitudinal axis or rotationally movable about the longitudinal axis, and by the movement of the inner cylinder, the overlap of the outer duct portion and the inner duct portion along the shell surface is adjusted according to the position of the piston along the stroke length. Relative to the environment of the fluid damper, the inner cylinder and / or the outer cylinder may move by virtue of its movement. Due to the structurally simple design of the fluid damper, preferably only the inner cylinder moves relative to the surroundings.

[0031] When the overlap of the duct portions decreases, the flow resistance of the damping fluid passing through the duct and the resulting damping force of the fluid damper increase. Thus, by the movement of the inner cylinder, the damping force of the fluid damper is automatically adjusted according to the position of the piston along the stroke length.

[0032] Preferably, when the piston is at one of the two end portions of the stroke length, the overlap between the outer and inner duct portions is less than when the piston is at the central portion of the stroke length, which is located between the end portions. In this embodiment, the movement of the inner cylinder increases the flow resistance of the damping fluid through the duct when the piston is at the end portion compared to when the piston is at the central portion.

[0033] In the event of an accident, the seatbelt extension speed initially increases significantly, then decreases again due to the seatbelt's holding force, and possibly contact between the occupant and the airbag, until the extension motion comes to a complete halt. Due to fluid dynamics, the damping force of conventional fluid dampers coupled to the seatbelt will also initially increase significantly with the extension speed, and then decrease again. This can lead to excessive load on the occupant due to excessive seatbelt holding force in the middle portion of the extension motion.

[0034] When the overlap of the duct portions is smaller when the piston is at the two end portions than when the piston is in the central portion, this prevents an excessive increase in damping force in the central portion due to the seat belt extension speed.

[0035] Preferably, the overlap of the duct portions continuously changes according to the position of the piston along the stroke length to ensure a uniform load on the occupant.

[0036] The progression of the overlap of the duct portion in relation to the piston position along the stroke length is preferably selected such that the damping force of the fluid damper remains constant along the stroke length as the expected progression of the withdrawal speed increases. For this purpose, the progression of the overlap in relation to the piston position along the stroke length is, for example, proportional to the progression of the withdrawal speed in relation to the piston position along the stroke length.

[0037] Preferably, when the piston is in the central portion, the overlap of the duct portions is complete, and / or when the piston is in one of the end portions, the duct portions do not overlap each other. In this way, particularly high variability of overlap is achieved, so that a constant damping force can be obtained even when the draw speed has high variability.

[0038] If the duct sections do not overlap, the damping fluid cannot flow through the duct from the front fluid chamber to the rear fluid chamber and / or reservoir, or vice versa. This means that if the fluid damper does not have other damping fluid ducts connecting the front fluid chamber to the rear fluid chamber and / or reservoir, the piston can only be shifted by the piston compressing the damping fluid in the shift direction at the front piston when there is no overlap.

[0039] Preferably, the inner cylinder is rotatable by shifting the piston about the longitudinal axis relative to the outer cylinder, so that the rotational movement of the inner cylinder adjusts the overlap of the outer duct portion and the inner duct portion along the shell surface according to the position of the piston along the stroke length.

[0040] The rotation of the inner cylinder relative to the outer cylinder is advantageous because it can be combined with the shift of the inner cylinder relative to the outer cylinder along the longitudinal axis, allowing the damping force to adapt to the mass or impact velocity of the occupant without mutual interference.

[0041] The inner cylinder is preferably rotatable relative to the outer cylinder about its longitudinal axis by a piston via a slide guide. For example, rotation of the inner cylinder relative to the outer cylinder can be achieved by the piston's projection engaging with a guide groove in the inner cylinder.

[0042] Preferably, at least one duct includes or is a radial duct, such as a radial nozzle, for passing damping fluid radially with respect to the longitudinal axis from the front fluid chamber through the shell walls of the inner cylinder and the outer cylinder. The radial duct is advantageous in that, with a particularly simple geometric shape of the duct, in particular with round or elongated holes passing through the inner and outer cylinders respectively, adjustment of the overlap of the duct portions can be achieved using the radial duct, depending on the position of the piston along the stroke length, for example due to the linear deflection of the inner cylinder relative to the outer cylinder along the longitudinal axis, and depending on the force acting on the piston, for example due to the rotational movement of the inner cylinder relative to the outer cylinder about the longitudinal axis. Thus, a seat belt holding force that is constant along the stroke length and adapted to the mass or impact velocity of the occupant can be achieved by the fluid damper in a particularly simple form.

[0043] The radial duct may, for example, connect from the front fluid chamber to a damping fluid reservoir located outside the internal space, or via a bypass, for example, between the outer cylinder and another cylinder arranged around the outer cylinder, to the rear fluid chamber.

[0044] The reservoir may have a fixed volume for containing the damping fluid, or it may be configured such that its volume adapts to the amount of damping fluid contained, for example, by having an elastic balloon. The reservoir may be closed or open for the damping fluid to the environment of the fluid damper. In particularly simple embodiments of the fluid damper, the reservoir may not be part of the fluid damper, but may be, for example, the interior space or partial interior space of the vehicle in which the fluid damper is used. In this embodiment, the damping fluid is preferably safe to contact with humans, and the damping fluid may be, for example, nitrogen, air, or water.

[0045] Preferably, at least one duct has grooves in the shell walls of the inner and outer cylinders, or is a groove, to guide the damping fluid past the piston from the front fluid chamber into the rear fluid chamber. The grooves are advantageous in that neither the duct portion nor the damping fluid reservoir needs to be outside the cylinder, as the damping fluid can remain inside the cylinder. Thus, the fluid damper can have a particularly space-efficient design.

[0046] The shell wall may have multiple spaced grooves along the longitudinal axis and / or in the circumferential direction about the longitudinal axis. Preferably, the shell wall has exactly one groove, which allows the cylinder to be manufactured in a particularly simple form and achieves particularly smooth transfer of the seat belt's holding force.

[0047] In the context of this invention, both a recess in a component having a depth defined by the bottom of the groove, and a complete opening through the component, are referred to as a “groove.” If the groove completely penetrates the shell wall, the cylinder must be surrounded by a sleeve in a manner that is tight to the damping fluid around at least one groove, in order to prevent unlimited leakage of damping fluid from the cylinder.

[0048] Preferably, the grooves are elongated, that is, at least one groove has a length substantially longer than its width perpendicular to its length.

[0049] Preferably, at least one groove has a cross-sectional area through which the damping fluid passes, and the cross-sectional area may be variable along the stroke length, for example, smaller at the two end portions of the stroke length than at the central portion of the stroke length located between the two end portions.

[0050] The flow resistance of the damping fluid, and therefore the damping force of the damper, is primarily determined by the cross-sectional area of ​​at least one groove adjacent to the piston at a given flow velocity of the damping fluid. Thus, a smaller cross-sectional area results in greater flow resistance and therefore greater damping force, while a larger cross-sectional area results in less flow resistance and therefore less damping force.

[0051] When the cross-sectional area adjacent to the piston is smaller at the two end portions of the stroke length than at the central portion, this prevents an excessive increase in damping force in the central portion due to the seat belt extension speed.

[0052] Preferably, the cross-sectional area changes continuously with respect to the stroke length in order to ensure a uniform load on the occupants.

[0053] Preferably, a series of cross-sectional areas corresponding to the stroke length are selected such that the damping force of the fluid damper remains constant as the expected progression of the withdrawal speed along the stroke length progresses. For this purpose, the series of cross-sectional areas corresponding to the stroke length are, for example, proportional to the progression of the withdrawal speed along the stroke length.

[0054] Preferably, at least one groove has a circumferential width about the longitudinal axis, and the width is variable along the stroke length, preferably smaller at the two end portions of the stroke length than at the central portion of the stroke length. A groove with variable width can have a constant depth radially with respect to the longitudinal axis, which is advantageous in that the thickness of the shell wall can be selected to be particularly small. Thus, the fluid damper can be manufactured in a particularly lightweight form with reduced material, for example, by fabricating a cylinder from a drawn tube.

[0055] Preferably, at least one groove has a radial depth with respect to the longitudinal axis, and the depth is variable along the stroke length, preferably smaller at the two end portions of the stroke length than at the central portion. A groove with variable depth can have a constant width in the circumferential direction about the longitudinal axis, which is advantageous in that it can be manufactured in a particularly simple form. For example, such a groove can be milled into the shell in a single work step.

[0056] Preferably, at least one groove spirally surrounds the longitudinal axis, and the groove pitch is variable along the stroke length along the longitudinal axis, preferably with a larger pitch at the two end portions of the stroke length than at the central portion. The spiral groove with variable pitch can have a constant depth radially with respect to the longitudinal axis, thereby allowing the shell wall thickness to be selected to be particularly small. Furthermore, such grooves are particularly simple to manufacture and can be produced, for example, by milling or laser cutting within the shell or by using a forming tool in a single work step.

[0057] In the context of this invention, the term "helical" means that at least one groove extends at least partially in a direction between the circumferential direction about the longitudinal axis and the axial direction along the longitudinal axis. Here, the groove preferably rotates at least once completely about the longitudinal axis, and more than once completely about the longitudinal axis. More than one complete rotation may have a favorable effect on the spring behavior of the fluid damper.

[0058] At least one groove preferably comprises an outer groove section within the outer cylinder and an inner groove section within the inner cylinder. If the inner groove section forms at least one groove together with the outer groove section, the inner groove section is an opening through the inner cylinder. The outer groove section may have a groove bottom or it may be an opening through the outer cylinder.

[0059] If the inner cylinder is movable relative to the outer cylinder by a shift of the piston relative to the outer cylinder along the longitudinal axis, the movement of the inner cylinder adjusts the overlap of the outer groove section and the inner groove section along the shell surface, preferably according to the position of the piston along the stroke length, and preferably the overlap of the outer groove section and the inner groove section is smaller when the piston is at one of the two end portions of the stroke length than when the piston is at the middle portion of the stroke length.

[0060] As a result, when the overlap between the outer and inner groove sections is small, the grooves have a shallow depth that is effective for allowing damping fluid to pass radially with respect to the longitudinal axis, and therefore have a small cross-sectional area through which the damping fluid passes. Consequently, due to the shift of the piston caused by the movement of the inner cylinder, the cross-sectional area is smaller when the piston is at the end portion than when the piston is at the center portion.

[0061] When the inner cylinder is displaced from its resting position relative to the outer cylinder by a force acting on the piston along its longitudinal axis, the deflection of the inner cylinder adjusts, preferably, in proportion to the magnitude of the force, the overlap of the outer groove section and the inner groove section along the shell surface, and the overlap of the outer groove section and the inner groove section is particularly greater when the inner cylinder is in its resting position than when the inner cylinder is displaced from its resting position.

[0062] Therefore, due to the deflection of the inner cylinder, as the force acting on the piston increases, and thus the damping force increases, the cross-sectional area of ​​the groove through which the damping fluid passes adjacent to the piston decreases. This means that if an occupant exerts a large force on the seat belt, and therefore a large force is exerted on the piston due to the occupant's large mass or high impact velocity, the occupant will be pulled back with a greater damping force than an occupant with a lighter weight or in an accident with a slower impact velocity. Thus, the damping force automatically adapts to the occupant's mass and impact velocity, on the one hand, keeping the load on the occupant by the seat belt as low as possible, and on the other hand, providing sufficient holding force so that the occupant does not hit the airbag with excessive kinetic energy.

[0063] Preferably, at least one groove has a height along the direction of deflection of the deflection from the resting position of the inner cylinder, and the height is constant along the stroke length. In this way, a predetermined deflection of the inner cylinder ensures that the same relative change in damping force occurs regardless of the piston position along the stroke length. Therefore, the adaptation of the damping force to the occupant's mass or impact velocity is carried out evenly along the entire stroke length, and the occupant receives a holding force that is applied evenly to the occupant's mass or impact velocity over the entire length of the seat belt extension.

[0064] The present invention relates to a belt force limiter for a seat belt, comprising a fluid damper according to the present invention for adjusting the retaining force of the seat belt.

[0065] For example, the piston of a fluid damper is fixed to a piston rod drawn out of the cylinder along the longitudinal axis of the fluid damper cylinder. The piston rod may be coupled to a seat belt via a coupling element, and the cylinder may have another coupling element that is coupled to the vehicle's seat or chassis, or vice versa. In this way, the piston can move in or out of the cylinder along the stroke length by the motion of pulling the seat belt against the seat or chassis. The pulling motion is damped by the damping force of the fluid damper, resulting in the aforementioned advantages and design options related to the fluid damper.

[0066] Further advantages, purposes, and features of the present invention will be described based on the following description and accompanying drawings, which illustrate exemplary subject matter according to the present invention. Features that are at least substantially identical in function to those in the drawings may be designated by the same reference numeral, and these features are not necessarily numbered and described in all drawings. [Brief explanation of the drawing]

[0067] [Figure 1] This is a schematic diagram showing a fluid damper according to the present invention.

[0068] [Figure 2] This figure shows the details of the grooves in the fluid damper shown in Figure 1.

[0069] [Figure 3] Figure 1 is a schematic longitudinal cross-sectional view showing the details of the shell wall in the cylinder of the fluid damper.

[0070] [Figure 4] This is a schematic longitudinal cross-sectional view showing details of the fluid damper in Figure 1 under conditions of heavy occupant weight.

[0071] [Figure 5] Another schematic longitudinal section showing details of the fluid damper in Figure 1 under conditions of light occupant weight.

[0072] [Figure 6] This is a schematic diagram illustrating the exemplified progression of the cross-sectional area adjacent to the piston of the fluid damper according to the present invention.

[0073] [Figure 7] This figure shows an exemplary progression of the cross-sectional area adjacent to the piston of the fluid damper according to the present invention in the case of an occupant with an upper body mass of 17.6 kg.

[0074] [Figure 8] This figure shows an exemplary progression of the cross-sectional area adjacent to the piston of the fluid damper according to the present invention in the case of an occupant with an upper body mass of 32.5 kg.

[0075] [Figure 9] This figure shows an exemplary simulation of the progression of the damping force of a fluid damper according to the present invention, depending on the position of the piston along the stroke length, in the case of an occupant with an upper body mass of 17.6 kg.

[0076] [Figure 10] This figure shows an illustrative simulation of the progression of the damping force of a fluid damper according to the present invention, depending on the position of the piston along the stroke length, in the case of an occupant with an upper body mass of 32.5 kg.

[0077] [Figure 11] This figure shows an illustrative simulation of the progression of the damping force of a fluid damper according to the present invention, depending on the position of the piston along the stroke length, in the case of an occupant with an upper body mass of 25 kg.

[0078] [Figure 12] This is a schematic diagram showing another fluid damper according to the present invention in a state with a light occupant weight.

[0079] [Figure 13]This is a schematic diagram showing the fluid damper in a state where a heavy occupant weight is applied. [Modes for carrying out the invention]

[0080] Figure 1 Figure 1 shows a schematic diagram of a fluid damper 100 according to the present invention for adjusting the holding force of a seat belt (not shown).

[0081] The illustrated fluid damper 100 comprises a cylinder 110 having an internal space 111 filled with damping fluid (not shown), and a piston (not shown) that is shiftable within the internal space 111 along the longitudinal axis LA of the cylinder 110 from the rear end portion HEB of the stroke length HS to the front end portion VEB of the stroke length HS.

[0082] The piston divides the internal space 111 into a front fluid chamber (not shown) located in front of the piston along the longitudinal axis LA, and a rear fluid chamber (not shown) located behind the piston along the longitudinal axis LA.

[0083] The piston is fixed to a piston rod 121 that extends from the cylinder 110 along the longitudinal axis LA.

[0084] The shell wall 114 of the cylinder 110 includes a duct 130 configured as a groove 132, which conductively connects the front fluid chamber and the rear fluid chamber for damping fluid.

[0085] For clarity, the groove 132 is shown as an opening through the shell wall 114. In this case, the cylinder 110 must be surrounded by a sleeve (not shown) that prevents damping fluid from leaking from the internal space 111 through the groove 132. Alternatively, the groove 132 may have a groove bottom that defines the depth of the groove 132 radially with respect to the longitudinal axis LA.

[0086] In the illustrated example, the groove 132 extends helically around the longitudinal axis LA, and the pitch of the groove 132 along the longitudinal axis LA is greater in the two end portions HEB and VEB of the stroke length HS than in the central portion ZB of the stroke length HS.

[0087] Thus, the groove 132 has a circumferential width centered on the longitudinal axis LA, and this width is smaller in the two end portions HEB and VEB of the stroke length HS than in the central portion ZB of the stroke length HS.

[0088] Thus, the groove 132 through which the damping fluid passes has a cross-sectional area, and this cross-sectional area is smaller in the two end portions HEB and VEB of the stroke length HS than in the central portion ZB of the stroke length HS located between the two end portions HEB and VEB.

[0089] In the illustrated example, the cylinder 110 comprises an outer cylinder 115 and an inner cylinder 116, the outer cylinder 115 and the inner cylinder 116 being arranged coaxially with the longitudinal axis LA, and the outer shell surface of the inner cylinder 116 is in sealed contact with the inner shell surface of the outer cylinder 115 for damping fluid.

[0090] The illustrated fluid damper 100 includes a spring element 140, for example, a helical compression spring. In the illustrated example, the spring element 140 biases the inner cylinder 116 to a stationary position along the longitudinal axis LA relative to the outer cylinder 115, and the inner cylinder 116 can be linearly deflected from the stationary position along the longitudinal axis LA relative to the outer cylinder 115 against the spring force of the spring element 140 by a force acting on the piston along the longitudinal axis LA.

[0091] Figure 2 Figure 2 schematically shows the details of the rear end portion HEB and the central portion ZB of the groove 132 in the fluid damper of Figure 1, with respect to the stroke length HS. The illustrated groove 132 is formed such that, in the circumferential direction with respect to the longitudinal axis LA, the width b of the central portion ZB is greater than that of the rear end portion HEB with respect to the stroke length HS.

[0092] The groove 132 is preferably formed to have a constant height h along the longitudinal axis LA along the entire stroke length HS.

[0093] Figure 3 Figure 3 shows a schematic longitudinal section along the longitudinal axis LA of detail of the shell wall 114 in the cylinder 110 of the fluid damper shown in Figure 1.

[0094] In Figure 3, it can be clearly seen that the cylinder 110 comprises an outer cylinder 115 and an inner cylinder 116 positioned inside it, and that the inner cylinder 116 is linearly deflectable along the longitudinal axis LA relative to the outer cylinder 115 (indicated by arrows).

[0095] The groove 132 in the shell wall 114 of cylinder 110 comprises an outer duct portion 135 configured as an outer groove section of outer cylinder 115 and an inner duct portion 136 configured as an inner groove section of inner cylinder 116. The inner duct portion 136 is an opening through which inner cylinder 116 passes. In the embodiment shown in Figure 3, the outer duct portion 135 has a depth defined by the groove bottom radially with respect to the longitudinal axis LA.

[0096] When the inner cylinder 116 is linearly displaced relative to the outer cylinder 115 along the longitudinal axis LA by a force acting, for example, on the piston (not shown) of a fluid damper along the longitudinal axis LA, the overlap of the two duct portions 135, 136, and therefore the depth of the groove 132 that is effective for passing damping fluid, changes radially with respect to the longitudinal axis LA.

[0097] In the relative positions of the inner cylinder 116 and the outer cylinder 115 shown in Figure 3, the two duct portions 135 and 136 have, for example, an overlap of about 50%. Thus, the depth of the outer duct portion 135 contributes only about 50% of the effective depth of the entire groove 132.

[0098] Figure 4 Figure 4 shows a schematic longitudinal section of detail of the fluid damper 100 of Figure 1 along the longitudinal axis LA in the case of a heavy occupant weight or a high impact velocity.

[0099] In Figure 4, it can be seen that the piston 120 of the fluid damper 100 divides the internal space 111 of the cylinder 110 of the fluid damper 100 into a front fluid chamber 112 and a rear fluid chamber 113 along the longitudinal axis LA.

[0100] Furthermore, it can be seen that the groove 132 in the shell wall 114 of the cylinder 110, which serves as a damping fluid duct 130, conductively connects the front fluid chamber 112 to the rear fluid chamber 113, and thus forms a bypass for the damping fluid around the piston 120.

[0101] The groove 132 comprises an outer duct portion 135 configured as an outer groove section of the outer cylinder 115 and an inner duct portion 136 configured as an inner groove section of the inner cylinder 116. The inner duct portion 136 is an opening through the inner cylinder 116. For clarity, the outer duct portion 135 is shown in Figure 4 as an opening through the outer cylinder 115. Alternatively, the outer duct portion 135 may have a depth defined by the groove bottom radially with respect to the longitudinal axis LA.

[0102] In the relative positions of the inner cylinder 116 and the outer cylinder 115 shown in Figure 4, the two duct portions 135 and 136 have minimal overlap. Thus, the depth of the outer duct portion 135 contributes minimally to the effective depth of the entire groove 132. As a result, the cross-sectional area for passing the damping fluid through the groove 132 is minimized, and the damping force of the fluid damper 100 is maximized.

[0103] The inner cylinder 116 is therefore preferably displaced to the position shown in Figure 4 in the event of an accident involving an occupant having the maximum mass for which the fluid damper 100 is designed and / or at the maximum impact velocity, thereby subjecting the occupant to the maximum holding force of a seat belt (not shown) coupled to the fluid damper 100.

[0104] Figure 5 Figure 5 shows another schematic longitudinal section of detail of the fluid damper 100 in Figure 1 along the longitudinal axis LA in the case of a light occupant weight or a low impact velocity.

[0105] Figure 5 differs from Figure 4 in that, in the relative positions of the inner cylinder 116 and outer cylinder 115 shown in Figure 5, the two duct portions 135 and 136 have the greatest overlap. Thus, the depth of the outer duct portion 135 contributes most to the effective depth of the entire groove 132. As a result, the cross-sectional area through which the damping fluid passes through the groove 132 is maximized, and the damping force of the fluid damper 100 is minimized.

[0106] Therefore, it is preferable that the inner cylinder 116 is displaced relative to the outer cylinder 115 to the position shown in Figure 5 by an accident involving an occupant having the minimum mass for which the fluid damper 100 is designed and / or at the minimum impact velocity, thereby ensuring that the occupant receives a minimum holding force from a seat belt (not shown) coupled to the fluid damper 100.

[0107] The relative positions of the inner cylinder 116 and the outer cylinder 115 shown in Figure 5 may coincide with the stationary position of the inner cylinder 116, which is biased by the spring element (not shown) of the fluid damper 100.

[0108] Figure 6 Figure 6 schematically illustrates the exemplary progression of the cross-sectional area Q of the groove in the cylinder shell of the fluid damper cylinder adjacent to the piston of the fluid damper according to the present invention, depending on the position of the piston along the piston stroke length HS.

[0109] The cross-sectional area Q adjacent to the piston is smaller at the two end portions HEB and VEB of the stroke length HS than at the central portion ZB of the stroke length HS located between the two end portions HEB and VEB.

[0110] Preferably, the progression of the cross-sectional area Q corresponds to the expected progression of the piston velocity along the stroke length HS. The progression of the piston velocity may be determined, for example, according to the individual collision behavior of the vehicle equipped with the fluid damper. The damping force of the fluid damper can be adapted to the uneven progression of the piston velocity by appropriate design of the progression of the cross-sectional area.

[0111] Figure 7 Figure 7 shows the position of the piston in millimeters along the piston stroke length HS, corresponding to the groove in the cylinder shell of the fluid damper cylinder adjacent to the piston of the fluid damper according to the present invention. 2 This shows an example of the progression of the unit cross-sectional area Q.

[0112] Figure 7 shows the inner cylinder of the fluid damper in a stationary position where the overlap between the inner and outer groove sections is maximized, resulting in the maximum cross-sectional area and therefore the minimum damping force. This state occurs, for example, when a seat belt coupled to the fluid damper is holding an occupant with an upper body mass of 17.6 kg in a vehicle with a mass of 1572 kg at a collision speed of 50 km / h.

[0113] Regarding the regulations for seat belt retention force, only the upper body mass of the retained occupant, including the occupant's head mass, arm mass, and torso mass, is relevant. Since the occupant's lower body is usually tightly secured to the seat by a lap belt, the lower body does not experience substantial acceleration relative to the seat, and therefore the mass of the lower body is irrelevant to the seat belt retention force.

[0114] Figure 8 Figure 8 shows the position of the piston in millimeters along the piston stroke length HS, corresponding to the groove in the cylinder shell of the fluid damper cylinder adjacent to the piston of the fluid damper according to the present invention. 2 This shows an example of the progression of the unit cross-sectional area Q.

[0115] Figure 8 shows the state in which the inner cylinder of the fluid damper is displaced to its maximum extent from its stationary position, thereby minimizing the overlap between the inner and outer groove sections, and thus achieving the minimum cross-sectional area and, consequently, the maximum damping force. This state occurs, for example, when a seat belt coupled to the fluid damper is holding an occupant with an upper body mass of 32.5 kg in a vehicle with a mass of 1572 kg at a collision speed of 50 km / h.

[0116] Figure 9 Figure 9 shows an illustrative simulation of the progression of the damping force F in kN units in the fluid damper according to the present invention, corresponding to the position of the piston in millimeters along the piston stroke length HS, when a seat belt coupled to the fluid damper holds an occupant with an upper body mass of 17.6 kg inside a vehicle with a mass of 1572 kg at a collision speed of 50 km / h.

[0117] In this case, the inner cylinder of the fluid damper is in a stationary position where the overlap between the inner groove section and the outer groove section is maximized, thereby obtaining the maximum cross-sectional area and therefore the minimum damping force. The damping force is, for example, approximately 2.5 kN in total and is substantially constant along the stroke length HS.

[0118] Figure 10 Figure 10 shows an illustrative simulation of the progression of the damping force F in kN units in the fluid damper according to the present invention, depending on the position of the piston in millimeters along the piston stroke length HS, when a seat belt coupled to the fluid damper holds an occupant with an upper body mass of 32.5 kg inside a vehicle with a mass of 1572 kg at a collision speed of 50 km / h.

[0119] In this case, the inner cylinder of the fluid damper is displaced to its maximum extent from its stationary position, thereby minimizing the overlap between the inner and outer groove sections, and thus achieving the minimum cross-sectional area and, consequently, the maximum damping force. The damping force is, for example, approximately 4.5 kN in total and is substantially constant along the stroke length HS.

[0120] Figure 11 Figure 11 shows an illustrative simulation of the progression of the damping force F in kN units in the fluid damper according to the present invention, depending on the position of the piston in millimeters along the piston stroke length HS, when a seat belt coupled to the fluid damper holds an occupant with an upper body mass of 25 kg inside a vehicle with a mass of 1572 kg at a collision speed of 50 km / h.

[0121] In this case, since the inner cylinder of the fluid damper is in an intermediate position between the stationary position and the maximum displacement from there, the damping force is between its minimum and maximum values, for example, totaling about 3.5 kN, and is preferably substantially constant along the stroke length HS.

[0122] The progression of the damping force F is determined by the mass of the inner cylinder and the hydrodynamic damping. In the progression of the damping force F shown in Figures 9 to 11, a mass of 275 g and damping of 500 Ns / m are assumed.

[0123] Figure 12 Figure 12 shows a schematic diagram of another fluid damper 100 according to the present invention for adjusting the holding force of a seat belt (not shown) in the case of a light occupant weight or a low impact velocity.

[0124] The fluid damper 100 shown in Figure 12 differs from the fluid dampers 100 in Figures 1 to 5 in that the duct 130 is formed as a radial duct 131 rather than as a groove. The radial duct 131 connects the front fluid chamber (not indicated) of the fluid damper 100 to, for example, a reservoir (not shown) of damping fluid located outside the internal space (not indicated) of the fluid damper 100. The radial duct 131 comprises an outer duct portion 135 that passes through the outer cylinder 115 of the fluid damper 100 and an inner duct portion 136 that passes through the inner cylinder (not indicated). For example, the duct portions 135 and 136 are each configured as elongated holes, and in particular, are configured to have the same cross-sectional area along the shell wall 114 of the cylinder 110.

[0125] For example, in the state shown in Figure 12, which corresponds to the stationary position of the inner cylinder 116, the duct portions 135 and 136 overlap each other radially with respect to the longitudinal axis LA. In this way, the damping fluid experiences little flow resistance within the radial duct 131, thereby providing the fluid damper 100 with a small damping force suitable, for example, as the holding force of a seat belt for a light occupant or a low impact velocity.

[0126] The inner cylinder can be deflected from a stationary position relative to the outer cylinder 115 along the longitudinal axis LA by a force acting linearly on the piston 120 along the longitudinal axis LA, for example, and the deflection of the inner cylinder adjusts the overlap of the outer duct portion 135 and the inner duct portion 136 along the shell surfaces of the outer cylinder 115 and the inner cylinder 116, depending on the magnitude of the force.

[0127] In addition, the inner cylinder is preferably movable along the longitudinal axis LA relative to the outer cylinder 115, by shifting the piston 120 along the longitudinal axis LA, and in particular by rotating about the longitudinal axis LA. The movement of the inner cylinder 116 adjusts the overlap of the outer duct portion 135 and the inner duct portion 136 along the shell surfaces of the outer cylinder 115 and the inner cylinder 116, depending on the position of the piston 120 along the stroke length HS. For this purpose, the piston 120 is connected to the inner cylinder, for example, via a slide guide 117.

[0128] Figure 13 Figure 13 shows a schematic diagram of the fluid damper 100 of Figure 12 in the case of a heavy occupant weight or a high impact velocity.

[0129] Heavy occupant weight or high impact velocity generates a large force along the longitudinal axis LA of the piston 120 of the fluid damper 100 via the seat belt. Consequently, the inner cylinder 116 is linearly displaced from its stationary position along the longitudinal axis LA (upward in Figure 13) relative to the outer cylinder 115, counteracting the spring force of the spring element 140. Thus, the overlap between the outer duct portion 135 and the inner duct portion 136 is reduced, increasing the fluid resistance acting on the damping fluid in the radial duct 131. In this way, the fluid damper 100 provides a greater damping force in the state shown in Figure 13 than in the state shown in Figure 12.

[0130] In comparison with Figure 12, the piston 120 of the fluid damper 100 is shifted in Figure 13 along the longitudinal axis LA, for example, from the central portion ZB of the stroke length HS to the rear end portion HEB of the stroke length HS. This displacement causes the inner cylinder 116 to rotate relative to the outer cylinder 115 about the longitudinal axis LA, for example, by a slide guide 117 between the piston 120 and the inner cylinder 116. The rotational movement of the inner cylinder 116 reduces the overlap between the outer duct portion 135 and the inner duct portion 136 in Figure 13 compared with Figure 12.

[0131] The reduction in overlap increases the flow resistance of the damping fluid through the radial duct 131, thereby preventing a reduction in the damping force of the fluid damper 100 when the piston moves along the longitudinal axis LA, with the end portions VEB and HEB of the stroke length HS moving more slowly than the middle portion ZB of the stroke length HS. [Explanation of Symbols]

[0132] 100 Fluid damper 110 cylinders 111 Interior space 112 Front fluid chamber 113 Rear fluid chamber 114 Shell Wall 115 Outer cylinder 116 Inner Cylinder 117 Slide Guide 120 pistons 121 Piston Rod 130 duct 131 Radial duct 132 Groove 135 Outer duct section 136 Inner duct section 140 spring elements b Width F Damping Force H Height HEB rear end HS stroke length LA Longitudinal axis Q cross-sectional area VEB front end ZB central part

Claims

1. A fluid damper (100) for adjusting the holding force of a seat belt, a. The fluid damper (100) comprises an outer cylinder (115) and an inner cylinder (116) arranged coaxially with respect to a common longitudinal axis (LA) within the outer cylinder (115), b. The inner cylinder (116) surrounds the internal space (111) filled with damping fluid, c. The fluid damper (100) comprises a piston (120) whose stroke length (HS) can be shifted along the longitudinal axis (LA) within the internal space (111), d. The fluid damper (100) comprises at least one duct (130), e. The at least one duct (130) conductively connects, for the damping fluid, a front fluid chamber (112) positioned in front of the piston (120) along the longitudinal axis (LA), to a rear fluid chamber (113) positioned behind the piston (120) along the longitudinal axis (LA), and / or a reservoir for the damping fluid positioned outside the internal space (111), f. The at least one duct (130) comprises an outer duct portion (135) within the shell wall of the outer cylinder (115) and an inner duct portion (136) within the shell wall of the inner cylinder (116), g. The outer shell surface of the inner cylinder (116) contacts the inner shell surface of the outer cylinder (115) to seal the damping fluid. h. A fluid damper (100) characterized in that, by a force acting on the piston (120) along the longitudinal axis (LA), the inner cylinder (116) is deflected from a stationary position relative to the outer cylinder (115), and the deflection of the inner cylinder (116) causes an adjustment in the overlap of the outer duct portion (135) and the inner duct portion (136) along the outer shell surface of the inner cylinder (116) and the inner shell surface of the outer cylinder (115), depending on the magnitude of the force.

2. The fluid damper (100) according to claim 1, wherein the inner cylinder (116) is capable of being linearly deflected along the longitudinal axis (LA) from the stationary position by the force acting on the piston (120) along the longitudinal axis (LA), and the linear deflection of the inner cylinder (116) causes an adjustment of the overlap of the outer duct portion (135) and the inner duct portion (136) along the outer shell surface of the inner cylinder (116) and the inner shell surface of the outer cylinder (115), depending on the magnitude of the force.

3. The fluid damper (100) according to claim 1, wherein the fluid damper (100) comprises a spring element (140), and the spring element (140) reacts to the deflection of the inner cylinder (116) relative to the outer cylinder (115) from the stationary position.

4. The fluid damper (100) according to claim 1, characterized in that the inner cylinder (116) is movable relative to the outer cylinder (115) by shifting the piston (120) along the longitudinal axis (LA), and the overlap of the outer duct portion (135) and the inner duct portion (136) along the outer shell surface of the inner cylinder (116) and the inner shell surface of the outer cylinder (115) is adjusted by the movement of the inner cylinder (116) according to the position of the piston along the stroke length (HS).

5. The fluid damper (100) according to claim 4, characterized in that the inner cylinder (116) is rotatable relative to the outer cylinder (115) about the longitudinal axis (LA) by shifting the piston (120), and the rotational movement of the inner cylinder (116) adjusts the overlap of the outer duct portion (135) and the inner duct portion (136) along the outer shell surface of the inner cylinder (116) and the inner shell surface of the outer cylinder (115) according to claim 4.

6. The fluid damper (100) according to claim 5, characterized in that the inner cylinder (116) is rotatable relative to the outer cylinder (115) about the longitudinal axis (LA) by the piston (120) via a slide guide (117).

7. The fluid damper (100) according to claim 1, characterized in that the at least one duct (130) includes a radial duct (131) that allows the damping fluid to pass from the front fluid chamber (112) radially with respect to the longitudinal axis (LA) through the shell walls of the inner cylinder (116) and the outer cylinder (115).

8. The fluid damper (100) according to claim 1, characterized in that the at least one duct (130) is provided with grooves (132) in the shell walls of the inner cylinder (116) and the outer cylinder (115) that guide the damping fluid past the piston (120) and into the rear fluid chamber (113) from the front fluid chamber (112).

9. a. The groove (132) through which the damping fluid passes has a cross-sectional area (Q), b. The fluid damper (100) according to claim 8, characterized in that the cross-sectional area (Q) is smaller at the two end portions (HEB, VEB) of the stroke length (HS) than at the central portion (ZB) of the stroke length (HS) located between the two end portions (HEB, VEB).

10. a. The groove (132) has a circumferential width (b) centered on the longitudinal axis (LA), b. The width (b) is characterized in that the two end portions (HEB, VEB) of the stroke length (HS) are smaller than the central portion (ZB) of the stroke length (HS). The fluid damper (100) according to claim 9.

11. a. The groove (132) spirally surrounds the longitudinal axis (LA), b. The fluid damper (100) according to claim 10, characterized in that the pitch of the groove (130) along the longitudinal axis (LA) is greater at the two end portions (HEB, VEB) of the stroke length (HS) than at the central portion (ZB) of the stroke length (HS).

12. a. The groove (132) has a height (h) along the direction of deflection of the deflection from the stationary position of the inner cylinder (116), b. The fluid damper (100) according to claim 11, characterized in that the height (h) is constant along the stroke length (HS).

13. A belt force limiter for seat belts, A belt force limiter comprising a fluid damper (100) according to any one of claims 1 to 12 for adjusting the holding force of the seat belt.

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