RU2555871C1 - Impact protection device of vehicle with passive damping system - Google Patents

Abstract

FIELD: automotive industry.

SUBSTANCE: invention relates to impact protection devices of vehicles (V), and can be used to ensure the safety of participants of road traffic accident (RTA). Rigid bumper bar 1 is made in the form of a toroidal curved shell combining parts with positive and negative Gaussian curvature of the middle surface, which cross section has an oval shape. On the rigid bumper bar a visco-elastic, recovering after hitting coating 2 of elastomeric material is fixed. The coating has a shape of toroidal shell which cross section has an oval shape. The back side of the rigid bumper bar is attached by inserts-fasteners 3 having a shape of catenoid to the spar 4 of the vehicle frame. The inserts-fasteners are yielding enough and made of visco-elastic material. The toroidal insert-fastener can be mounted at a slight angle to the longitudinal axis of the V and at a strike is able to be wedged itself and to wedge the spar of the V.

EFFECT: most reasonable reduction of energy of visco-elastic deformations in the collision is provided, simplifying the design, cost efficiency of the material in production, improvement of protection and facilitation of bumper recovery after accident.

9 cl, 8 dwg

Description

The invention relates to the automotive industry, and in particular to shockproof devices in the field of transport equipment, and can be used in cars to ensure the safety of participants in a road accident.

The prior art known shockproof devices, consisting either of:

- from the combination "bumper beam - coating - elastic-damping connection with the frame of the vehicle (TC)", for example, according to the patent for the invention (RU 2133679, B60R 19/28, publ. 07.27.1999);

- individually - a rigid bumper bar covered with elastic material; rigid bar without coating, but connected by an elastic-damping connection with the frame of the vehicle according to the patents (US 3841683, B60R 19/10 publ. 10/15/1974; GB 1370267, B60R 19/00, publ. 10/16/1974; FR 2159931, B60R 19/00, publ. 06/22/1973);

- shockproof bumpers using magnetoactive elastomers as damping elements according to patents (US 5971451, B60R 19/02, publ. 10.26.1999; RU 2424133, B60R 19/26, F16F 9/53, 07.20.2011; RU 2514999, B60R 19 / 02, B60R 19/30, publ. 05/10/2014) and the international application for invention (WO 2009/088974 A1, publ. 16.07.2009);

- shock-proof TS bumpers having various shell forms of a rigid bumper beam according to patents: DE 19849358, B60R 19/18, publ. 11/05/2000, (B-shaped), DE 19847743, B60R 19/02, publ. 04/20/2000, (Y-shaped), patent JP 2844555, publ. 04/10/1994 (O-shaped), etc. and damping elements in the form of cylindrical shells (patent JP 3007744, publ. 02.28.1995).

The disadvantages of the above structures shock protection devices TS include:

- low efficiency of protection as a pedestrian during a collision with a vehicle, and a car (driver) when hitting an obstacle;

- technically complex structures;

- none of them fully includes the merits of the other options above;

- do not use the advantages of toroidal shell shapes.

The prototype of the present invention is taken to be a shock-proof device TS containing a transverse rigid bumper beam with elastic elements fixed to it for connecting to the frame of the vehicle in the form of insert-mountings made of magnetically active elastomers (MAE) and coated with a layer of elastic, restored after removing the shock load, material also from the MAE according to the patent for the invention (RU 2424133, B60R 19/26, F16F 9/53, 07/20/2011);

The disadvantage of the design of the prototype is the complexity of the design, the use of expensive smart materials and, in particular, technically sophisticated devices for inducing an external electromagnetic field, as well as the absence of toroidality of a rigid bumper beam and the possibility of ovalization of its cross section, which increases its rigidity under bending deformations and, as a result, it is not possible to effectively reduce the impact force.

The objective of the proposed invention is to improve the protection of both a pedestrian during a collision with a vehicle, and a car (driver) when hitting an obstacle, by creating a shock-proof device with a simple structure, the structural elements of which allow to realize the strength and stiffness parameters as much as possible, without resorting to the use of expensive smart materials and complex devices for inducing an external electromagnetic field, as well as ease of repair.

The object of the invention provides a passive shock damping system with sufficient design simplicity and is implemented as follows, a shock-proof device, mainly for a passenger car, contains a transverse rigid bumper bar having an elastic-viscous coating of elastomeric material and an insert-mount transverse rigid bumper bar to the spar vehicle, according to the invention, the difference is that it is made in the form of a composite toroid the shell configuration of its main elements: an elastic-viscous coating, a transverse rigid bumper beam and an insert-attachment of the bumper beam to the vehicle side member, while the cross section of a toroidal rigid bumper beam (for example, in the form of Cassini ovals) and a toroidal shell of an elastic-viscous coating of elastomeric material ( the cross-sectional shape can be simple or composite, for example, in the form of cylinders or Cassini ovals) made oval, and the shape of the bumper beam combines joints with positive and negative Gaussian curvature of the median surface, and the bumper bar itself is supported by toroidal insert-attachments (for example, integrated into the vehicle spar) in the form of a catenoid with a negative Gaussian curvature of the median surface, which can also be installed parallel to the longitudinal axis of the TC, and can also be installed and at a small angle, not more than 5 °, in the direction of the longitudinal axis of the vehicle, which contributes, in addition to the effective perception of shock load (near the edges of racing toroidal shells, a concent tion of bending stresses and significant normal voltage) wedging a catenoid, and it can effectively reduce the rigidity as compared with the most common in the automotive industry-cylindrical shock-absorbing inserts fasteners.

In addition, another difference is that:

- the toroidal shell of the viscoelastic coating and the toroidal rigid bumper bar in cross section may be in the form of Cassini ovals;

- the toroidal shell of the viscoelastic coating of the rigid bumper beam can be made in the form of a layered structure consisting of alternating layers, for example, a rubber layer with a metal mesh;

- the toroidal shell of the viscoelastic coating of the rigid bumper bar may consist of several shells working as a whole; the toroidal shell of the viscoelastic coating can be coated with a light and durable fabric synthetic material containing reinforcing fibers of polyparaphenylene terephthalamide, for example Kevlar, Twaron and Nomex;

- a toroidal rigid bumper bar can be made of an elastically viscous composite material, for example fiberglass, with fastening to a spring spar and realizing an elastic connection between them;

- the shape of the toroidal shells of the rigid bumper beam and the viscoelastic coating can be made different from each other in shape.

- holes or cutouts are provided in some of the shells of the rigid bumper beam and the insert-fasteners.

The viscoelastic elastomeric material of the first of the composite toroidal shells, mounted on a rigid bumper bar of the TS and acting as a coating, is capable of both accumulating impact energy and dissipating it. The toroidal shape of the elastomeric coating provides the most optimal stiffness parameters and the most optimal reduction in the energy of viscoelastic deformations in a collision with an obstacle, as well as the subsequent distribution and transfer of shock loads to a rigid bumper bar, in addition, the combination of sections with positive and negative curvature gives a decrease in bending stiffness for the latter .

The toroidal shape of a rigid bumper beam, the oval shape of its cross section and its curvature in comparison, for example, with a straight beam reduces its rigidity under bending loads and contributes to an increase in the energy of elastic-viscous deformations, which leads to a more effective decrease in the energy of elastic-viscous deformations when a vehicle collides with an obstacle.

In addition, the toroidal nature of the shell structures allows to a certain extent to save material. For example, with the following dimensions of the catenoid: upper radius R = 5.4 cm, lower radius r = 5.25 cm, height H = 8 cm, the use of a catenoid insert compared to a cylinder insert with similar dimensions R × H gives material savings in 10% at the same wall thickness h.

Another difference is that the toroidal elastomeric coating of the bumper bar can be a layered shock-absorbing structure with alternating rubber layers with a metal mesh, which, as is known from literature and, in particular, from the field of helicopter engineering, helps to reduce shock waves.

Another difference is that the toroidal shell of the viscoelastic coating of the rigid bumper beam can consist of several shells working as a whole, which provides increased strength by reducing internal mechanical stresses and provides better maintainability in case of damage to the coating (explanation of claim 4 of the claims )

Another difference is that the toroidal shell of the viscoelastic coating is coated with a durable synthetic fabric material containing reinforcing fibers of polyparaphenylene terephthalamide, for example Kevlar, Twaron, Nomex, which ensures the integral operation of all coating components. In addition, the multilayer structure increases long-term strength: according to reference data, the Kevlar tensile strength is 5 times greater than structural steel, which, in turn, is an order of magnitude stronger than the plastics used in modern car bumpers (explanation to claim 5 of the claims).

Another difference is that the toroidal rigid bumper beam can be made of an elastic-viscous composite material, for example fiberglass, with fastening to the spar of the spring type, and realizing an elastic connection between them. As is known from literature, fiberglass is lighter and stronger than structural steel, has better corrosion resistance, and the energy of deformations accumulated before fracture is higher for fiberglass. A spring mount similar to a beam of equal strength along the length of equal bending resistance provides both material saving (lightening the structure weight) and the advantages of pure bending during deformation (explanation to claim 6 of the claims).

Another difference is that the toroidal insert-fasteners connecting the bumper bar with the vehicle spars are installed not strictly in the direction of the longitudinal axis of the vehicle, but at a small angle (not more than 5 °). The wedging creates significant compressive and tensile stresses in the toroidal nodes of the fastener and bumper structures, which are proportional to the value of α ^-1 - the angle of the tangent to the surface of the toroidal shell. In this case, the most complete, in comparison with the most common cylindrical assemblies in the automotive industry, is an increase in the long-term dynamic strength of the vehicle bumper and the impact force is automatically reduced (with the same value of the shock pulse).

Another difference is that in some of the layers of the rigid bumper beam and insert-fasteners, holes or cuts of such a shape and size are possible that the strength of the structure does not significantly decrease and there is no significant stress concentration, but the holes or cuts decrease construction weight. For example, meridional cuts (holes) in a toroidal insert-mount provide a reduction in impact force with the same shock impulse (explanation to paragraph 9 of the claims).

The technical result achieved by using the invention is: the most rational reduction of the energy of viscoelastic deformations in the process of collision of the vehicle due to the use of toroidal shell elements optimizing the rigidity of the structure, the simplicity of the proposed structure and material saving in its manufacture; this ensures both the safety of the bumper design at low impact speeds (preserving the vehicle’s presentation) and efficient energy absorption at higher speeds (increasing the passive safety of the vehicle and ensuring the safety of the driver / passengers), as well as the safety of pedestrians and other objects of impact (reducing severity of potential injury / damage).

The proposed shockproof device is illustrated by drawings, which depict:

FIG. 1 is a cross-sectional construction of an impact protection device (top view) with toroidal elasto-viscous insert-mountings mounted parallel to the direction of the longitudinal axis of the vehicle;

FIG. 2 is a cross-sectional composite structure of a shock protection device (top view) with toroidal, visco-elastic inserts-fasteners mounted at a small angle in the direction of the longitudinal axis of the vehicle;

FIG. 3 - toroidal viscoelastic insert-mount, General view;

FIG. 4a is an embodiment of couplers of a vehicle bumper bar with an insert-mount, top view;

FIG. 4b is an embodiment of conjugations of a rigid bumper bar of a vehicle with an insert-mount, longitudinal section;

FIG. 5 is a composite structure of a shock-proof device, a cross-section through an insert-mount;

FIG. 6 - variants of ovalization forms of an elastomeric toroidal coating;

FIG. 7 - possible forms of ovalization of the cross section of a rigid bumper beam TS;

FIG. 8 is a graph of perception of shock load of the vehicle.

The shock-proof device TS contains: a transverse rigid bumper beam 1 in the form of a toroidal curvilinear shell combining sections with positive and negative Gaussian curvature of the middle surface, the cross section of which is in the form of Cassini ovals with an elastic-viscous coating 2 restored from impact from the elastomeric material, and the coating also has the shape of a toroidal shell, the cross section of which is oval, in particular Cassini ovals, and the rear of the rigid bumper the beam 1 is attached by means of catenoid inserts 3 having the shape of a catenoid to the spar 4 of the vehicle frame, while the inserts 3 are sufficiently flexible and made of visco-elastic material, for example technical rubber or similar elastomers; moreover, a toroidal insert-mount with a negative Gaussian curvature of the median surface can be installed at a slight angle to the longitudinal axis of the vehicle and, upon impact, in addition to the above properties, it can both wedge itself and wedge the vehicle spar.

The device operates as follows.

When a vehicle collides with an obstacle (at low speeds, no more than 8-16 km / h), the elastic-viscous coating 2 of the rigid bumper beam 1 is deformed, mitigating the effects of the impact, for example, for a pedestrian (other object of impact), then a hard bumper beam 1 perceives the received shock load (both locally concentrated and distributed over any part of the bumper) and distributes it evenly over the entire frontal plane of the front of the car (transferring to spars 4 and further to the body safety grill), while to reduce the consequences of collision process includes specific cross-sectional shape, by which is increased viscoelastic deformation energy, as a result of reducing the stiffness of the whole structure of the proposed passive damping system.

With a sufficiently significant impact force (exceeds the above speed range), the load perceived by the elastic-viscous coating 2 is transferred to a rigid bumper beam 1, which is included in the process of mitigating the effects of impact and, due to its cross-sectional shape (has significantly lower rigidity for bending deformations), it is more optimal distributes the shock load over the entire bumper structure due to the presence of a coating and ovalization of the beam shape and then transfers forces to the viscoelastic insert-mount 3 with a negative Gaussian the mean surface curvature, which in addition to the impact load effective perception (near the edges of the thin toroidal shells occurs concentration of bending stresses and significant normal voltage) wedged in catenoid, which also can effectively optimize the rigidity and reduce (damp or dissipate) the impact impulse.

In a frontal collision (at low speeds up to 8-16 km / h - the range of parking, driving in traffic jams, etc.), deformations of the structural elements of the car are small, therefore the visco-elastic coating 2 of the bumper bar 1 and the visco-elastic insert-mount 3 are deformed in this way that the presentation of both the car and the object of impact (for example, a fence or another car) is preserved, minimizes the pedestrian injuries.

After the collision, the viscoelastic coating 2 of the bumper beam 1, as well as the viscoelastic insert-mount, 3 can restore their original shape in order to ensure both the presentation of the car and the functionality of the vehicle bumper design.

In a frontal collision at more significant speeds, not only the toroidal rigid bumper beam 1, but also the elastic-viscous bond of the bumper beam with the vehicle spar in the form of toroidal insertions-fasteners 3 are included in the energy removal work 3. Their general deformation, taking away the main part of the impact energy already positively affects the safety of the vehicle itself and the people in it.

) определяется временем, затрачиваемым на его деформирование. Жесткость бруса существенно зависит от изгибных деформаций поперечных сечений. Предварительная овализация увеличивает время, затрачиваемое на восприятие ударной нагрузки, и при одинаковом внешнем ударном импульсе автоматически снижает силу удара.As you know, when the shock load on the bumper bar of the vehicle changes in stiffness (with the same external shock impulse

) is determined by the time spent on its deformation. The stiffness of the beam significantly depends on the bending deformations of the cross sections. Preliminary ovalization increases the time taken to perceive the shock load, and with the same external shock impulse automatically reduces the force of impact.

It has been established by calculation and experimental methods that ovalization of a curved section of a bar with an external impact bending load of 10-12% leads to a decrease in bending stiffness by 1.6 ÷ 1.7 times. When choosing a rational form of both the cross section of a rigid bumper beam and the insert-attachment in the iterative algorithm for searching for geometric parameters of the curve of the middle surface at each stage of the numerical experiment, the energy functional of elastic strains of a single section of the beam in the zone of maximum bending stresses is taken as the optimality criterion (excluding shear deformations):

ξ ₁ , ξ ₂ , are the changes in the main curvature of the middle surface in the meridional and circumferential directions, respectively;

τ — torsion strain;

µ is the Poisson's ratio;

h is the wall thickness of the shell;

A ₁ , A ₂ - Lame parameters;

α ₁ , α ₂ - curvilinear coordinates of the middle surface.

By changing the main curvatures of the catenoid, as can be seen from the above formula, it is possible to obtain the optimum (the value required for the structure) decrease in the energy of elastic-viscous deformations.

As you know, for a beam symmetrically loaded and pivotally attached at the edges, the deflection value is determined by the formula:

где:

Where:

F is the current load;

l is the length of the beam section between the supports;

E is the Young's modulus of the beam material;

J is the axial moment of inertia of the cross section of the beam.

осевые моменты инерции для эллипса:

овалы Кассини описывает плоская алгебраическая кривая четвертого порядка, уравнение которой в прямоугольных декартовых координатах имеет вид: (х²+у²)²-2с(х²-у²)=а⁴-с⁴, причем в рассматриваемых нами случаях сечения должны удовлетворять соотношению для параметров

(а при соотношениях

как известно, имеет место обычный овал).Axial moment of inertia for a circle (see Fig. 7):

axial moments of inertia for an ellipse:

Cassini ovals are described by a fourth-order plane algebraic curve, the equation of which in rectangular Cartesian coordinates has the form: (x ² + y ² ) ² -2s (x ² -y ² ) = a ⁴ -s ⁴ , and in the cases under consideration, the sections must satisfy relation for parameters

(and with the relations

as you know, there is a regular oval).

, то видно, что овализация поперечного сечения за счет варьирования параметрами, входящими в формулу момента инерции, приводит к уменьшению жесткости при одинаковом расходе материала.On the other hand, it has been experimentally established and statistically confirmed by numerous studies that the perception of the shock load of the vehicle occurs stepwise in accordance with the above graph (see Fig. 8). It should be noted that, for example, comparing sections in the form of circular (D = 5 cm, h = 5 mm) and oval rings (ovalization of the order of 10%) of the same perimeter and wall thickness, i.e. with the same material consumption, a change in rigidity of the order of 1.5 times is achieved. Since stiffness

, it can be seen that ovalization of the cross section due to variation in the parameters included in the formula of the moment of inertia leads to a decrease in stiffness at the same material consumption.

Thus, the shock-proof device of a vehicle with a composite toroidal shell configuration is a simple, economical, passive damping system and implements the maximum reduction in the energy of elastic-viscous deformations in a car collision, ensuring injury safety for the driver, passengers and pedestrians in the event of an accident.

Claims (9)

1. Impact protection device of a vehicle with a passive damping system, mainly for a passenger car, comprising a transverse rigid bumper beam having an elastic-viscous coating of elastomeric material, and insert-attachment of the transverse rigid bumper beam to the vehicle side member, characterized in that the main elements of the impact protection device : visco-elastic coating, transverse rigid bumper beam and insert-attachment of the bumper beam to the vehicle side member are made a shell-shaped configuration, the cross-section of a toroidal rigid bumper bar and an elastic-viscous coating of elastomeric material made oval, and the shape of the bumper bar combines sections with positive and negative Gaussian curvature of the median surface, and the bumper bar rests on toroidal insert-mounts in the form of a catenoid with negative Gaussian curvature of the median surface, which are installed at a small angle of not more than 5 °, in the direction of the longitudinal axis of the trans mercury means and are capable, upon impact, of both wedging themselves and wedging the vehicle spar structure. 2. The shockproof device according to claim 1, characterized in that the configuration of the toroidal shells of the viscoelastic coating and the rigid bumper beam can be in the form of Cassini ovals. 3. The shockproof device according to claim 1, characterized in that the toroidal shell of the viscoelastic coating of the rigid bumper bar is made of a layered structure consisting of alternating layers, for example, a rubber layer with a metal mesh. 4. The shockproof device according to claim 1, characterized in that the toroidal shell of the viscoelastic coating of the rigid bumper bar can consist of several shells working as a whole. 5. The shockproof device according to claim 1 or 4, characterized in that the toroidal shell of the viscoelastic coating is coated with a durable synthetic fabric material containing reinforcing fibers of polyparaphenylene terephthalamide, for example Kevlar, Twaron and Nomex. 6. The shockproof device according to claim 1, characterized in that the toroidal rigid bumper bar can be made of an elastically viscous composite material, for example fiberglass, with fastening to the spar of the spring type, and realizing an elastic connection between them. 7. The shockproof device according to claim 1, characterized in that the shapes of the toroidal shells of the rigid bumper beam and the viscoelastic coating can be different from each other. 8. The shockproof device according to claim 1, characterized in that the toroidal insert-mountings of the transverse rigid bumper beam are installed parallel to the longitudinal axis of the vehicle. 9. The shock-proof device according to claim 1, characterized in that openings are provided in the toroidal shells of the rigid bumper bar and the insert fasteners to lighten the weight of the structure.

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