A telescopic-friction composite energy absorption device

Abstract

The present invention provides a telescopic-friction composite energy absorption device, in which a telescopic base and a friction base are arranged in parallel and are opposite to the uniform force plate on the outside of the anti-climbing tooth of a railway vehicle; there are multiple telescopic tubes, the front end of which is fixed on the uniform force plate; the rear end is fixed at the guide hole on the telescopic base; the inner diameter of the guide hole is smaller than the inner diameter of the telescopic tube; each telescopic tube is also provided with a friction rod, the outer diameter of the friction rod is smaller than the inner diameter of the telescopic tube; the front end of the friction rod is fixed on the uniform force plate, and the rear end extends to the outside of the rear end of the telescopic tube, freely passes through the guide hole, and is installed in the friction hole of the friction base with an interference fit. The telescopic-friction composite energy absorption device provided by the present invention cleverly combines the principles of telescopic energy absorption and friction energy consumption, and realizes a composite energy absorption with higher and more stable energy absorption. The present invention has a simple structure, is easy to install, and has low cost, and can be installed at the front end of a railway vehicle crossbeam to realize the anti-climbing energy absorption function.

Description

Technical Field

[0001] The invention relates to a telescoping-friction composite energy absorbing device, belonging to a railway vehicle energy absorbing device. Background Art

[0002] Improving passive safety protection capabilities is an important theme in railway vehicle design. A special energy absorption device is usually installed at the front end of a railway vehicle. When a train collision occurs, the impact kinetic energy is converted into other forms of energy dissipation as much as possible, thereby protecting the lives of railway vehicle occupants.

[0003] Among the many forms of energy-absorbing structures currently used for railway vehicles, the most common one is the use of thin-walled metal pipes to dissipate energy through large plastic deformation. Under certain aspect ratio and thickness requirements, metal pipes will exhibit progressive buckling deformation when subjected to axial compression, forming layers of regular wrinkles. Depending on the specifications and materials of the pipes, these wrinkles may be accordion-shaped or diamond-shaped. However, in any case, each time a wrinkle is produced, the metal thin wall will usually exhibit two types of deformation: twisting and flow extension, corresponding to two energy dissipation modes: twisting energy absorption and extension energy absorption. Corresponding to the force-displacement curve, the axial compression impact force of the metal thin-walled pipe presents a large peak and a section that is an overall platform and contains multiple small fluctuations, which is considered to have a relatively ideal stable energy absorption capacity.

[0004] However, with the improvement of train collision standards, a single metal thin-walled tube energy absorption structure has gradually been unable to meet the needs of collision energy absorption. On the one hand, the total energy consumption of the plastic deformation energy absorption of the metal tube is closely related to the size and material of the pipe. If the energy absorption of the energy absorption device is to be improved, it is inevitable to increase the diameter, wall thickness, length and other parameters of the metal tube, which greatly increases the installation space of the energy absorption device and may even destroy the original progressive buckling of the metal tube; on the other hand, with the increase of the geometric parameters of the metal tube, the mass of the energy absorption device will also increase, which runs counter to the demand for lightweight railway vehicles. At the same time, the total energy absorption of the energy absorption device with a metal thin-walled structure as the core is fixed after design and production. It is difficult to change the energy absorption size by some simple means, and it is difficult to meet the design goal of today's energy absorption device to accurately control the energy absorption size according to different energy absorption requirements.

[0005] On the other hand, friction is a very classic energy dissipation behavior and has been widely applied in the field of braking. By means of the frictional resistance generated when two moving surfaces come into contact with each other, kinetic energy and potential energy are converted into heat energy and dissipated, thus achieving the purpose of braking. Although frictional energy dissipation is a very classic design in the field of braking, it has not been applied in the design of dedicated energy absorption structures for rail trains at present. This is related to a large number of factors such as R & D and design costs, processing and installation difficulties, reliability, the lack of compatibility between a mature structural design and the existing energy absorption structures of railway trains, and the lack of a reliable assessment of the energy consumption. Summary of the Invention

[0006] Based on the traditional metal plastic large deformation energy absorption device, and fully considering the mechanical characteristics of plastic deformation through experiments, finite element simulations and theoretical analyses, the present invention makes a clever composite design of frictional energy dissipation and telescopic deformation energy dissipation, and provides a composite energy absorption structure that realizes both telescopic-friction energy dissipation behaviors within a limited energy absorption stroke range on the premise of having almost no adverse effects on the processing technology, material cost, installation space and lightweight degree of the energy absorption device. This composite structure has stable energy absorption, a large energy absorption capacity, adjustable and controllable energy absorption magnitude, and is ingeniously designed, simple in structure, low in cost and convenient for installation, and has broad application prospects in the field of passive safety protection of railway vehicles.

[0007] The specific technical solution is as follows:

[0008] The telescopic-friction composite energy absorption device includes a telescopic tube, a telescopic base, a friction base and a friction rod;

[0009] The telescopic base and the friction base are arranged in parallel and are opposite to the equalizing plate outside the anti-climbing teeth of the railway vehicle;

[0010] There are multiple telescopic tubes, the front ends of which are fixed on the equalizing plate; the rear ends are fixed at the guiding holes on the telescopic base; the inner diameter of the guiding hole is smaller than the inner diameter of the telescopic tube;

[0011] Each telescopic tube is also provided with a friction rod, the outer diameter of which is smaller than the inner diameter of the telescopic tube; the front end of the friction rod is fixed on the equalizing plate, and the rear end extends to the outside of the rear end of the telescopic tube, freely passes through the guiding hole, and is installed in the friction hole of the friction base by interference fit.

[0012] The telescopic tube is a thin-walled pipe fitting made of plastic metal material;

[0013] The telescopic base is made of rigid material, and is provided with a telescopic base mounting hole and a telescopic base weight-reducing hollowing telescopic base mounting hole;

[0014] The friction rod is made of rigid wear-resistant material.

[0015] The described friction base is provided with a friction base mounting hole and a weight-reducing hollow in the friction base; the friction hole is made of a friction material.

[0016] The friction hole is provided with a heat dissipation mechanism.

[0017] The telescopic-friction composite energy absorption device provided by the present invention ingeniously combines the principles of telescopic energy absorption and friction energy dissipation, and realizes a composite energy absorption with higher and more stable energy absorption capacity on the premise of hardly having an adverse impact on the processing technology, material cost, installation space, and lightweight degree of traditional energy absorption devices. The structure of the present invention is simple, easy to install, and low in cost, and can be installed at the front end of the crossbeam of a railway vehicle to achieve the anti-climbing energy absorption function. In addition, the relevant principles of the core energy absorption part other than the anti-climbing teeth of the present invention can also be applied to the front end, side end, and tail of an automobile and other parts that require improved safety protection, and are also applicable to other occasions with high energy absorption requirements such as the landing buffer of an aircraft and explosion protection, and have very wide engineering application value. Description of the Drawings

[0018] Figure 1 is the assembly drawing of the telescopic-friction composite energy absorption device of the present invention;

[0019] Figure 2 is the exploded view of the telescopic-friction composite energy absorption device of the present invention;

[0020] Figure 3 is the structure drawing of the telescopic base of the present invention;

[0021] Figure 4 is the structure drawing of the friction base of the present invention;

[0022] Figure 5 is the functional schematic diagram of the telescopic-friction composite energy absorption device of the present invention;

[0023] Figure 6 is the principle disassembly drawing of the telescopic energy dissipation part of the present invention;

[0024] Figure 7 is the principle disassembly drawing of the friction energy dissipation part of the present invention. Detailed Embodiments

[0025] As Figure 1 and Figure 2 shown, the telescopic-friction composite energy absorption device constructed according to the present invention is composed of an anti-climbing tooth 1, a force equalizing plate 2, a telescopic tube 3, a telescopic base 4, a friction base 5, and a friction rod 6.

[0026] The anti-climbing teeth 1 are fixedly connected to the force equalizing plate 2, which is the basic structure of railway vehicles and not the focus of the present invention. The force equalizing plate 2 is a rigid metal plate, with the anti-climbing teeth fixedly connected to the front end, and several telescopic tubes 3 and several friction rods 6 (two are taken as examples hereinafter) fixedly connected to the rear end. The number of telescopic tubes 3 is the same as that of the friction rods 6. The telescopic tubes 3 are sleeved outside the friction rods 6, and there is no special connection between them and they are in free contact.

[0027] The telescopic tubes 3 are made of metal materials with excellent plasticity, such as aluminum alloy, etc., and are fixedly connected to the force equalizing plate 2 and the telescopic base 4 at both ends respectively.

[0028] The telescopic base 4 is made of materials with relatively high stiffness, and the stiffness is greater than that of the telescopic tube 3, such as stainless steel, etc., and includes several telescopic base mounting holes 41 (four are taken as examples), guiding holes 42 and telescopic base weight reduction cutouts 43, etc., as Figure 3 shown. The telescopic base 4 is fixedly connected to the front cross beam of the railway vehicle underframe through the telescopic base mounting holes 41. The aperture of the guiding hole 42 is smaller than the inner diameter of the telescopic tube 3 but larger than the diameter of the friction rod 6. Thus, the telescopic base 4 and the force equalizing plate 2 restrict all degrees of freedom of the telescopic tube 3, and squeeze the telescopic tube 3 to undergo plastic telescopic deformation during the collision process, dissipating a large amount of impact kinetic energy. There is no fixed standard for the telescopic base weight reduction cutouts 43 on the base 4. In addition to the cut surface, a large number of structures such as grooving and opening holes can also be used. As long as the structural strength is ensured, the structure should be made as lightweight as possible.

[0029] The friction rod 6 inside the telescopic tube 3 is made of relatively rigid wear-resistant materials, such as aluminum-silicon composite materials, etc. The length of the friction rod 6 is greater than that of the telescopic tube 3. Its top end is fixedly connected to the force equalizing plate 2. The front half part is sleeved inside the telescopic tube 3 and in free contact, and the rear half part respectively passes through the guiding holes 42 of the telescopic base 4 and the friction holes 52 of the friction base 5. The friction rod 6 can move freely in the holes of the telescopic base 4, and extends backward along the guiding holes 42 of the base during the collision process without obvious plastic deformation. The friction rod 6 and the friction holes 52 of the friction base 5 adopt interference fit.

[0030] The friction base 5 is as Figure 4 shown, and includes several friction base mounting holes 51, friction holes 52 and friction base weight reduction cutouts 53, etc. The base 5 is fixedly connected to the front cross beam of the railway vehicle underframe through the friction base mounting holes 51. The friction rod 6 passes through the friction holes 52 of the friction base 5, and the hole and the rod adopt interference fit. The material of the friction holes 52 is special friction material, such as various modified rubbers. According to the actual situation, the entire friction base 5 can be made of friction material, or the friction base 5 can use general metal materials, and only special friction materials are arranged around the friction holes 52, or according to the need of friction heat dissipation, the friction holes 52 are designed for heat dissipation in a dispersed or grooved manner (such as Figure 4As shown). During a collision, the friction rod 6 moves at high speed in the friction hole 52 of the friction base 5, generating intense friction and dissipating kinetic energy.

[0031] The invention basis and working principle of this telescopic-friction composite energy-absorbing device are as follows: The composite energy-absorbing device of the present invention is installed at the front end of the underframe of a railway train, usually two are arranged symmetrically. When a railway vehicle has a collision accident, this energy-absorbing device simultaneously performs two functions of telescoping and friction, dissipating a large amount of energy. As Figure 5 shown, the anti-climbing teeth 1 at the very front play the role of preventing climbing. The force equalizing plate 2 and the telescopic base 4 respectively play the roles of upper and lower pressing plates. The telescopic tube 3 between them is the main body for telescopic energy dissipation. The distance between the force equalizing plate 2 and the telescopic base 4 is equal to the length L of the telescopic tube 1 , which is directly related to the telescopic energy dissipation stroke. On the one hand, the friction rod 6 is the main body for friction energy dissipation, mainly dissipating energy through friction with the friction hole of the friction base 5 during the collision process. The distance L between the force equalizing plate 2 and the friction base 5 2 minus the distance L between the telescopic base and the friction base 5 3 is directly related to the friction stroke of the friction rod 6. On the other hand, the friction rod 6 is located inside the telescopic tube 3 and also plays the role of guiding the telescopic tube 3 to telescopic, effectively avoiding the instability problem of the telescopic tube 3 due to its too large length-diameter ratio.

[0032] Specifically, the telescopic tube 3 is a metal tube, sandwiched between the force equalizing plate 2 and the telescopic base 4. Although there is a guiding hole 42 on the telescopic base 4, the telescopic tube 3 is coaxial with the guiding hole 42 but the inner diameter of the telescopic tube 3 is larger than the diameter of the guiding hole 42, as Figure 6 shown. During an impact, the telescopic base 4 is equivalent to a rigid wall for the telescopic tube 3. The telescopic tube 3 will successively undergo three deformation stages of elastic deformation, plastic deformation, and deformation densification under axial compression, and its axial length will be greatly reduced, corresponding to a large peak force, a long and gently fluctuating platform force F p and a rapid increase in the final impact force respectively on the impact force-displacement curve. The integral of the impact force-displacement curve, that is, the area enclosed with the horizontal coordinate axis, corresponds to the energy absorption of the telescopic deformation, as Figure 5 shown. Since the strokes corresponding to the impact peak and densification stages are very small and contribute little to the integral of the curve, the telescopic tube 3 can be simplified as rigid-plastic to obtain its telescopic energy dissipation E t as Equation 1:

[0033] E t =F p L 1 η (1)

[0034] In the formula, η is equal to the densification strain of the telescopic tube, which is about 0.75. It can be seen that without changing the material, wall thickness, diameter, etc. of the thin-walled tube, the energy dissipated by the telescopic tube is related to the axial length L of the telescopic tube 1 directly. Therefore, in order to improve the energy dissipation, it is often desired that the telescopic tube has a larger tube length. However, on the other hand, an excessively large tube length will inevitably cause the Euler buckling phenomenon of the axial compression of the pipe fitting, greatly reducing the energy absorption of the pipe fitting. Therefore, in the present invention, a long straight friction rod 6 is further added inside the telescopic tube 3. The diameter of the friction rod 6 is smaller than the diameter of the guide hole 42 on the telescopic base 4. Therefore, during the impact, it can pass through backward from the guide hole 42 and will not be subjected to excessive axial force, and will not undergo large plastic deformation like the telescopic tube 3. On the other hand, the diameter of the friction rod 6 is also smaller than the inner diameter of the telescopic tube 3. Therefore, the internal space of the telescopic tube 3 can be fully utilized to improve the deformation stability of the pipe fitting, as Figure 5 shown

[0035] Furthermore, the length L of the friction rod inside the telescopic tube 3 2 is greater than the length L of the telescopic tube 1 , and their tops are jointly fixed on the uniform force plate 2. Therefore, the friction rod 6 will protrude a certain distance from the rear of the telescopic tube 3. The present invention makes full use of this distance to further arrange a friction base 5, as Figure 7 shown. In particular, the diameter of the friction rod 6 is slightly larger than the diameter of the friction hole 52 on the friction base 5. The friction rod 6 passes through the friction hole 52, that is, the two are in an interference fit with an interference amount δ. During the collision, although the friction rod 6 can move backward from the friction hole 52 without large plastic deformation, it will generate intense friction with the friction hole 52, dissipating a large amount of energy, thus achieving the design purpose of doubling the energy absorption of the special energy absorption device through two energy dissipation modes simultaneously under a limited energy absorption stroke

[0036] Furthermore, the contact pressure-displacement curve corresponding to the friction process is a relatively flat platform-shaped curve, that is, the contact pressure F f almost remains unchanged during the impact, and the integral of the curve corresponds to the friction energy dissipation, which is similar to the telescopic deformation, as Figure 5 shown. During the impact, the friction energy dissipation and the telescopic energy dissipation occur simultaneously and synchronously, and the friction stroke is equal to the telescopic stroke. There is formula 2

[0037] L 1 =L 2 -L 3 (2)

[0038] Therefore, the telescopic energy dissipation and frictional energy dissipation of the entire telescopic-frictional energy absorption device can be linearly superimposed to obtain the total energy dissipation of the device. It is not difficult to see that on the premise of hardly changing the installation space of the device and having little impact on lightweight, the energy dissipation of the telescopic-frictional energy absorption device of the present invention can reach more than twice that of the energy absorption device with the traditional single energy dissipation method, which is a very ingeniously designed energy absorption device.

[0039] Furthermore, for the contact friction force of the interference fit between the friction rod 6 and the friction hole 52, there is Equation 3:

[0040]

[0041] In the formula, C 1 is the stiffness coefficient of the friction rod, C 2 is the stiffness coefficient of the friction hole, E 2 is the elastic modulus of the material of the friction hole, d is the nominal diameter of the friction rod, with the unit of mm, and they are basically fixed and unchanged when the material and dimensions of the structure are determined. μ is the friction coefficient, and δ is the average interference amount, with the unit of μm.

[0042] The frictional energy dissipation E f of the energy absorption device has Equation 4:

[0043] E f = F f L 1 η (4)

[0044] Similar to the telescopic energy dissipation, the frictional energy dissipation is also directly related to the axial length L 1 of the telescopic tube, and has nothing to do with the length L 2 of the friction rod. Therefore, in the present invention, the design of the friction rod can improve the deformation stability of the telescopic tube, increase the designable length L 1 of the telescopic tube, and while increasing the telescopic energy dissipation E 1 , it will also act on the frictional energy dissipation itself and increase the frictional energy dissipation E 2 . On the other hand, it also shows that the length L 2 of the friction rod should not be too long on the premise of being greater than the length L 1 of the telescopic tube, so as to ensure the lightweight of the structure.

[0045] Furthermore, the total energy dissipation of the energy absorption device has Equation 5:

[0046]

[0047] It can be obtained from Equation 5 that the total energy consumption of the energy absorption device is directly related to the average interference δ between the friction rod and the friction hole. In the actual design process, according to the actual energy consumption requirements of railway vehicles, it is very simple to control the amount of frictional energy consumption only by controlling the interference between the friction tube and the friction hole, thereby further controlling the total energy absorption of the entire energy absorption device, enabling the energy absorption device to achieve the design goal of adjustable and controllable energy absorption, which is of great significance.

Claims

1. A telescopic-friction composite energy absorption device, characterized in that, it includes a telescopic tube (3), a telescopic base (4), a friction base (5) and a friction rod (6); The telescopic base (4) and the friction base (5) are arranged in parallel and are opposite to the equalizing plate (2) outside the anti-climbing teeth (1) of the railway vehicle; There are multiple telescopic tubes (3), the front ends are fixed on the equalizing plate (2); the rear ends are fixed at the guiding holes (42) on the telescopic base (4); the inner diameter of the guiding holes (42) is smaller than the inner diameter of the telescopic tubes (3); Each telescopic tube (3) is also provided with a friction rod (6) inside, and the outer diameter of the friction rod (6) is smaller than the inner diameter of the telescopic tube (3); the front end of the friction rod (6) is fixed on the equalizing plate (2), and the rear end extends to the outside of the rear end of the telescopic tube (3), freely passes through the guiding hole (42), and is installed in the friction hole (52) of the friction base (5) by interference fit; The equalizing plate (2) and the telescopic base (4) respectively act as upper and lower pressing plates. The telescopic tubes (3) between them are the main body of telescopic energy consumption, and the friction rod (6) is the main body of friction energy consumption. During the collision, it frictions with the friction hole of the friction base (5) to dissipate energy. The friction rod (6) is located inside the telescopic tube (3) and also plays a role in guiding the telescopic of the telescopic tube (3); Specifically, when an impact occurs, the telescopic base (4) is equivalent to a rigid wall for the telescopic tube (3). When the telescopic tube (3) is axially compressed, it will successively undergo three deformation stages: elastic deformation, plastic deformation, and deformation densification. During the impact, the friction rod (6) inside the telescopic tube (3) passes through the guiding hole (42) backward and moves backward from the friction hole (52), generating intense friction with the friction hole (52) to dissipate energy; During the impact, friction energy consumption and telescopic energy consumption occur simultaneously and are superimposed.

2. A telescopic-friction composite energy absorption device according to claim 1, characterized in that, the telescopic tube (3) is a thin-walled pipe fitting and is made of a plastic metal material.

3. A telescopic-friction composite energy absorption device according to claim 1, characterized in that, the telescopic base (4) is made of a rigid material, is provided with a telescopic base mounting hole (41), and is also provided with a telescopic base weight reduction hollow (43).

4. A telescopic-friction composite energy absorption device according to claim 1, characterized in that, the friction rod (6) is made of a rigid wear-resistant material.

5. A telescopic-friction composite energy absorption device according to claim 1, characterized in that, the friction base (5) is also provided with a friction base mounting hole (51) and a friction base weight reduction hollow (53); the friction hole (52) is made of a friction material.

6. A telescopic-friction composite energy absorption device according to claim 1, characterized in that, the friction hole (52) is provided with a heat dissipation mechanism.

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