Automobile crash energy absorption device and design method

Abstract

The present application relates to a kind of automobile collision energy-absorbing device and design method, including movement guide structure, mass block, energy-absorbing structure, force limiting failure structure and movement limiting structure, movement guide structure is set in automobile chassis, mass block is installed in the rear end of movement guide structure, and can be linear motion along movement guide structure, movement limiting structure is used to limit the final movement position of mass block, energy-absorbing structure is used to absorb mass block movement collision energy, force limiting failure structure is connected with mass block, for fixing mass block on movement guide structure.The present application utilizes mass block and vehicle chassis relative motion to absorb part of energy of vehicle frontal collision, reduces the deformation of the rest of vehicle body structure, reduces the harm to the people in the car, improves vehicle collision safety performance.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle passive safety protection, and more particularly to an automobile collision energy absorption device and a design method thereof. Background Art

[0002] Passive safety devices are designed to minimize personal injury after a traffic accident and are crucial to the safety of vehicle occupants. Currently, passive safety features, particularly frontal collision protection, primarily absorb the significant impact energy through deformation of the front bumper, energy boxes, and longitudinal beams. In low-speed collisions, the bumper and energy boxes, due to their optimal design, absorb the impact energy, minimizing the impact acceleration transmitted to the rear vehicle structure and minimizing injury to the occupants.

[0003] However, when a vehicle collides at medium or high speed, the instantaneous collision energy is enormous. Due to the limited space available for energy absorption in the front of the vehicle body, even after the bumper, crash box, and front longitudinal beams have all collapsed and deformed to absorb the energy, it is still insufficient to absorb the intense collision energy. The excess collision energy is further absorbed by the bending and deformation of the rear body structure. Although the rear body structure has high rigidity and minimal deformation, the occupants' survival space is sufficient, but the collision acceleration exceeds the human body's tolerance limit, which can also cause serious personal injury to the occupants. Summary of the Invention

[0004] The object of the present invention is to provide an automobile collision energy absorbing device and a design method to solve the above problems.

[0005] The present invention adopts the following technical solutions:

[0006] A vehicle collision energy absorption device includes a motion guide structure, a large mass block, an energy absorbing structure, a force limiting failure structure and a motion limiting structure. The motion guide structure is arranged on the vehicle chassis, and the front and rear ends of the motion guide structure are respectively facing the front and rear ends of the vehicle. The large mass block is installed at the rear end of the motion guide structure and can move linearly along the motion guide structure. The motion limiting structure is fixedly installed at the front end of the motion guide structure and is used to limit the final motion position of the large mass block. The energy absorbing structure is arranged between the motion limiting structure and the large mass block and is used to absorb the motion collision energy of the large mass block. The force limiting failure structure is connected to the large mass block and is used to fix the large mass block on the motion guide structure.

[0007] Further, the motion guiding structure includes two chute rails arranged in parallel on the lower end surface of the longitudinal beam of the vehicle chassis, several sliding blocks arranged in the chute rails, and an installation bracket fixedly connected to the sliding blocks respectively. The large mass object is installed on the installation bracket, and there are two motion limiting structures, which are respectively fixedly installed on the lower end surface of the longitudinal beam of the vehicle chassis in front of the chute rails.

[0008] Further, the energy absorption structure is two square thin-walled beams. One end of the square thin-walled beam is fixedly installed on the motion limiting structure, and the other end of the square thin-walled beam faces the large mass block.

[0009] Further, the force-limiting failure structure is a fixing part. The fixing part penetrates and connects the sliding block and the chute rail respectively to fix the sliding block in the chute rail.

[0010] Further, the force-limiting failure structure is the square thin-walled beam. The front end of the square thin-walled beam is fixedly installed on the motion limiting structure, and the rear end of the square thin-walled beam extends to abut against the installation bracket.

[0011] Further, a friction material layer is also laid on the inner side surface of the chute rail, and the friction material layer contacts and abuts against the sliding block.

[0012] Further, the vehicle is an electric vehicle, and the large mass block is a vehicle power battery pack.

[0013] A design method for an automobile collision energy absorption device includes the following steps:

[0014] Step 1, the automobile collision energy absorption device is this device. Determine the collision vehicle speed condition that triggers the collision energy absorption of this device as the collision condition. Set the vehicle mass M and the collision speed V. When the vehicle speed is greater than or equal to V during a collision, trigger the energy absorption operation of the automobile collision energy absorption device.

[0015] Step 2, determine the absorbed collision energy of this device under the collision condition. Obtain the kinetic energy of the vehicle during a collision from the vehicle mass M and the collision speed V The mass of the large mass object is m, and the kinetic energy of the large mass object during a collision Determine the energy absorption ratio n borne by this device according to the energy absorption ratio range of the main structural components of the vehicle. 0 < n < 1. The collision energy absorbed by this device E2 = nE, and E2 ≤ E1.

[0016] Step 3, design the force-limiting value of the force-limiting failure structure. The force-limiting value of the force-limiting failure structure is to ensure that the force-limiting failure structure will not fail to limit the force and trigger the collision energy absorption of this device during the emergency braking condition and low-speed collision during normal driving. The force-limiting value is greater than the force on the large mass block under the emergency braking condition, that is, F 限 ≥ ma制动 , F 限 is the force limit value, a 制动 is the braking acceleration of the vehicle under emergency braking conditions. The force-limiting failure structure is a fixed component, and the force limit value is the breaking force of the fixed component. The force-limiting failure structure is a square thin-walled beam, and the force limit value is the collision peak load of the square thin-walled beam.

[0017] Step 4: Design of energy absorbing structure. The energy absorbing structure adopts square thin-walled beams. The energy absorbing structure absorbs energy by collapsing and deforming. The average force of the energy absorbing structure is F. ave =nE / s, s is the effective compression length of the thin-walled closed beam structure. The size, thickness and material of the square thin-walled beam are selected through simulation calculation or theoretical formula calculation. For the square thin-walled beam, F can be calculated by the following formula ave =9.58σ0t 5 / 3 b 1 / 3 , where σ0 is 0.9 to 0.95 times the tensile strength of the square thin-walled beam material, t is the wall thickness of the square thin-walled beam, and b is the side length of the square thin-walled beam or half the sum of the lengths of any two adjacent sides.

[0018] From the above description of the structure of the present invention, it can be seen that compared with the prior art, the present invention has the following advantages:

[0019] 1. The present invention utilizes a motion guide structure, a large mass block, and an energy-absorbing structure installed on the vehicle chassis. When a vehicle collides at high speed, the relative motion between the large mass block and the vehicle chassis absorbs part of the energy of a frontal collision, thereby reducing deformation of the remaining vehicle structures, alleviating injuries to vehicle occupants, and improving vehicle collision safety performance.

[0020] 2. The large mass block of the present invention is preferably an automotive power battery pack. Given that the battery pack mass currently accounts for a considerable proportion of the entire vehicle, and with the trend of electric drive axles gradually replacing traditional shaft transmissions, the space at the bottom of the frame where the battery pack is placed can be used as energy absorption space to alleviate the lack of energy absorption space at the front of the vehicle body, improve the frontal collision performance of the vehicle, make full and reasonable use of the normal structure of the vehicle, minimize changes to the entire vehicle, and reduce the cost of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 This is a simplified schematic diagram of the structural relationship of Example 1 of the present invention.

[0022] Figure 2 This is a structural diagram of embodiment 1 of the present invention.

[0023] Figure 3 Schematic diagram of a motion guidance structure according to an embodiment of the present invention.

[0024] Figure 4 for Figure 3Cross-sectional view of the chute track in the AA direction.

[0025] Figure 5 This is a cross-sectional view of the chute track according to the second embodiment of the present invention.

[0026] Figure 6 This is a structural diagram of embodiment 3 of the present invention.

[0027] Figure 7 This is a load-crushing deformation curve of the square thin-walled beam of the present invention.

[0028] Among them, the numbers in the figure are: motion guide structure 10, slide track 11, sliding block 12, mounting bracket 13, large mass block 20, energy absorption structure 30, square thin-walled beam 31, force limiting failure structure 40, fixing part 41, friction material layer 42, motion limiting structure 50, L-shaped steel baffle 51, and automobile chassis 60. DETAILED DESCRIPTION

[0029] The specific implementation of the embodiment of the present invention is described below with reference to the accompanying drawings.

[0030] Example 1

[0031] Reference Figure 1 and Figure 2 A vehicle collision energy absorption device includes a motion guide structure 10, a large mass block 20, an energy absorbing structure 30, a force limiting failure structure 40 and a motion limiting structure 50. The motion guide structure 10 is arranged on the vehicle chassis 60, and the front and rear ends of the motion guide structure 10 are respectively facing the front and rear directions of the vehicle. The large mass block 20 is installed at the rear end of the motion guide structure 10 and can move linearly along the motion guide structure 10. The motion limiting structure 50 is fixedly installed at the front end of the motion guide structure 10 to limit the final motion position of the large mass block 20. The energy absorbing structure 30 is arranged between the motion limiting structure 50 and the large mass block 20 to absorb the motion collision energy of the large mass block 20. The force limiting failure structure 40 is connected to the large mass block 20 to fix the large mass block 20 on the motion guide structure 10.

[0032] Reference Figure 2 and Figure 3Specifically, this embodiment takes an electric car as an example, and the motion guide structure 10 includes two chute rails 11, four sliding blocks 12 and a mounting bracket 13. The chute rails 11 are arranged parallel to the lower end surface of the longitudinal beam of the vehicle chassis 60, and the two ends of the chute rails 11 are respectively facing the front and rear directions of the vehicle. The four sliding blocks 12 are symmetrically and slidably arranged in the two chute rails 11. The mounting bracket 13 is a rectangular frame structure, and its four bracket feet are respectively fixedly connected to the four sliding blocks 12. In this embodiment, the large mass block 20 is preferably an automotive power battery pack. The mounting bracket 13 is composed of a plurality of square steels welded together, which is used to install the automotive power battery pack while also protecting the automotive power battery pack.

[0033] Reference Figure 2 and Figure 3 The motion limiting structure 50 consists of two L-shaped steel baffles 51 with reinforcing ribs at the angles between them. The two L-shaped steel baffles 51 are welded to the lower end surfaces of the longitudinal beams of the vehicle underframe 60 at the front end of the chute track 11 (towards the front of the vehicle). After the large mass 20 is assembled within the mounting bracket 13, the mounting bracket 13 is moved to the rear end of the chute track 11 (towards the rear of the vehicle), and the mounting bracket 13 and the large mass 20 are secured to the rear end of the chute track 11 via the force-limiting failure structure 40.

[0034] Reference Figure 3 and Figure 4 In the present invention, the force-limiting failure structure 40 provides force limiting, which prevents the large mass 20 from moving due to inertia during normal vehicle operation, braking, or low-speed collisions, thereby triggering the collision energy absorption device. The force-limiting failure structure 40 is a breakable fastener 41, such as a rivet or bolt, or a steel wire rope. In this embodiment, at least two rivet fasteners 41 are preferably provided. The two rivet fasteners 41 extend through the two sliding blocks 12 at the rear end of the chute track 11 and the chute track, respectively, securing the two sliding blocks 12 within the chute track 11.

[0035] Reference Figure 2 and Figure 3 The energy-absorbing structure 30 of the present invention comprises two square thin-walled beams 31, one end of which is fixedly mounted on the motion-limiting structure 50, while the other end faces the large mass 20. Specifically, one end of the square thin-walled beam 31 is welded to the blocking surface of the L-shaped steel baffle 51, while the other end extends horizontally toward the two bracket legs of the mounting bracket 13. The square thin-walled beam 31 is provided with a collapse groove to guide the "accordion"-style collapse.

[0036] Reference Figures 1 to 4In specific use, when a vehicle is subjected to a high-speed collision while traveling, the large mass 20 continues to move forward under the action of inertia. The force-limiting failure structure 40, subjected to the load transmitted by the large mass 20, reaches the force limit and breaks, i.e., the rivet fastener 41 breaks under the transmitted load. The large mass 20 and the mounting bracket 13 then acquire an initial forward velocity and move forward along the motion guide structure 10. The front bracket foot of the mounting bracket 13 contacts the square thin-walled beam 31, causing the square thin-walled beam 31 to collapse and deform, absorbing energy until the energy-absorbing structure 30 reaches its maximum deformation. The motion-limiting structure 50 then limits the large mass 20 and the mounting bracket 13 to their final stopping position. Specifically, the present invention utilizes the motion guide structure 10, the large mass 20, and the energy-absorbing structure 30 mounted on the vehicle underframe. In the event of a high-speed collision, the relative motion of the large mass 20 and the vehicle underframe absorbs a portion of the energy of a frontal collision, thereby reducing deformation of the remaining vehicle structure, alleviating injuries to vehicle occupants, and improving the vehicle's collision safety.

[0037] Example 2

[0038] Reference Figure 5 This embodiment is essentially identical in structure to the first embodiment and will not be further described here. The difference lies in that a friction material layer 42 is also provided on the inner side of the chute track 11, and the friction material layer 42 contacts and supports the sliding block 12. The friction material layer 42 of the present invention can be added directly to the inner side of the chute track 11, based on the first embodiment. Alternatively, it can be considered as a force-limiting failure structure 40, i.e., without the use of rivet fasteners 41 or other fasteners, and the maximum static friction between the friction material layer 42 and the sliding block 12 serves as the force limiting mechanism 40. When a vehicle collides at high speed, the inertial force of the large mass block 20 and the mounting bracket 13 exceeds the maximum static friction, causing the sliding block 12 to slide within the friction material layer 42 of the chute track 11.

[0039] Reference Figure 5 The friction material layer 42 is used alone and is only suitable for small power battery packs or other relatively small large mass objects 20, and is only an alternative embodiment. In this embodiment, preferably based on the first embodiment, that is, based on the design of the rivet fixing member 41, a friction material layer 42 is also laid on the inner side of the slide track 11. The maximum static friction force of the friction material layer 42 not only provides a portion of the force limiting value for the force limiting failure structure 40, but also absorbs a portion of the collision energy during the sliding process of the large mass object 20 and the mounting bracket 13, thereby providing additional collision energy absorption space for the device and further improving the vehicle's collision safety performance.

[0040] Example 3

[0041] Reference Figure 6, this embodiment has basically the same structure as Embodiment 1 and will not be elaborated here. The difference lies in that the force-limiting failure structure 40 is a square thin-walled beam 31. The front end of the square thin-walled beam 31 is fixedly installed on the movement limiting structure 50, and the rear end of the square thin-walled beam 31 extends to abut against the mounting bracket 13. Specifically, on the basis of Embodiment 1, the rivet fixing part 41 is not designed, and the rear end of the square thin-walled beam 31 is directly abutted or welded to the bracket feet of the mounting bracket 13. This embodiment preferably uses direct welding rather than abutting. The energy absorption structure 30, that is, the initial load required for the buckling deformation of the square thin-walled beam 31, is used as the force-limiting value of the force-limiting failure structure 40. When a vehicle undergoes a high-speed collision, the inertial forces of the large mass block 20 and the mounting bracket 13 are greater than the initial load force of the energy absorption structure 30 for buckling deformation, and the energy absorption structure 30 begins to buckle and deform to absorb the collision energy.

[0042] In the present invention, the square thin-walled beam 31 can be used alone as the force-limiting failure structure 40, or in combination with Embodiment 1 as a part of the force-limiting failure structure 40. That is, on the basis of designing the rivet fixing part 41, the rear end of the square thin-walled beam 31 can also be directly welded to the bracket feet of the mounting bracket 13.

[0043] A design method for an automobile collision energy absorption device includes the following steps:

[0044] Step 1, the automobile collision energy absorption device is this device. Determine the collision vehicle speed condition for triggering the collision energy absorption of this device as the collision condition, and set the vehicle mass M and the collision speed V. When the vehicle speed is greater than or equal to V during a collision, trigger the energy absorption operation of the automobile collision energy absorption device. For example, a head-on collision with a rigid wall at a vehicle speed of 50 km / h is used as the collision condition. A lower vehicle speed is regarded as a low-speed collision, and the inertial forces of the large mass block 20 and the mounting bracket 13 are less than the force-limiting value of the force-limiting failure structure 40, and the collision energy is absorbed by the structures such as the vehicle head and bumper of the automobile, and this device is not triggered to absorb the collision energy. On the contrary, a vehicle speed equal to or higher than this value is regarded as a high-speed collision, and the inertial forces of the large mass block 20 and the mounting bracket 13 reach the force-limiting value of the force-limiting failure structure 40, triggering this device to absorb the collision energy.

[0045] Step 2, determine the absorbed collision energy of this device under the collision condition. Obtain the kinetic energy of the vehicle during the collision from the vehicle mass M and the collision speed V The mass of the large mass object is m, and the kinetic energy of the large mass object during the collision Determine the energy absorption ratio n borne by this device according to the energy absorption ratio range of the main structural components of the vehicle, 0 < n < 1. The energy absorption collision energy E2 of this device =, and E2 ≤ E1.

[0046] Step three, design the force limit value of the force limit failure structure 40. The force limit value of the force limit failure structure 40 is to ensure that the force limit failure structure 40 will not fail to limit the force and trigger the collision energy absorption of the device during emergency braking conditions and low-speed collisions during normal driving. The force limit value can be obtained through model tests or collision simulation experiments. The force limit value is greater than the force exerted on the large mass object 20 under emergency braking conditions, that is, limit ≥ braking, where limit is the force limit value and braking is the braking acceleration of the vehicle under emergency braking conditions.

[0047] In addition, when the force-limiting failure structure 40 is a fixing part 41 , the force-limiting value is the breaking force of the fixing part 41 . The force-limiting value of the force-limiting failure structure 40 can be adjusted according to the number, material, and other aspects of the fixing parts 41 .

[0048] When the friction material layer 42 is applied to the motion guide structure 10 , the maximum static friction between the friction material layer 42 and the sliding block 12 will also be calculated as a part of the force limit value.

[0049] When the square thin-walled beam 31 of the energy-absorbing structure 30 is used alone or in combination as the force-limiting failure structure 40, the square thin-walled beam 31 undergoes accordion-like crushing deformation under the guided collapse structure. In essence, it is a continuous cycle of three stages: instability-instability state destruction-crushing deformation. In this process, the load size of the thin-walled beam shows a wavy trend with the crushing distance. Its load-displacement curve is as follows: Figure 7 As shown, the collision peak load of the thin-walled closed beam structure should be designed as the limit force value, or be included as part of the limit force value.

[0050] Step 4: Design the energy absorbing structure 30. The energy absorbing structure 30 uses a square thin-walled beam 31. The square thin-walled beam 31 is used to absorb energy by deformation. The average force on the energy absorbing structure 30 is F. ave =nE / s, s is the effective compression length of the square thin-walled beam 31. The size, thickness and material of the square thin-walled beam 31 are selected through simulation calculation or theoretical formula calculation. For the square thin-walled beam 31, F can be calculated by the following formula ave =9.58σ0t 5 / 3 b 1 / 3 , where σ0 is 0.9 to 0.95 times the tensile strength of the material of the square thin-walled beam 31, t is the wall thickness of the square thin-walled beam 31, and b is the side length of the square thin-walled beam 31, or half of the sum of the lengths of any two adjacent sides. Specifically, when the cross-section of the square thin-walled beam 31 is square, b is the side length of the square thin-walled beam 31; when the cross-section of the square thin-walled beam 31 is rectangular, b is half of the sum of the long side length and the short side length of the square thin-walled beam 31. A square thin-walled beam 31 of appropriate size, thickness, and material is selected so that the average force on the energy-absorbing structure 30 does work within the effective compression length s to achieve the target energy absorption requirements.

[0051] In addition, when the friction material layer 42 is applied to the motion guide structure 10, the friction motion between the friction material layer 42 and the sliding block 12 will also be calculated as part of the collision energy absorption. The friction material layer 42 is subjected to a sliding friction force F ave =F 滑 =μ 动 mg, where μ 动 is the coefficient of kinetic friction between the applied friction material and the massive object 20. According to the fact that the work done by friction is equal to the energy absorbed, the effective distance of the applied friction material is calculated as: 滑 = / ( 动 ).

[0052] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited to this. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. An automobile collision energy absorption device, characterized in that: The invention comprises a motion guiding structure, a large mass block, an energy absorbing structure, a force limiting failure structure and a motion limiting structure, wherein the automobile is an electric automobile, the large mass block is an automobile power battery pack, the motion guiding structure is arranged on the automobile chassis, the front end and the rear end of the motion guiding structure are respectively oriented toward the front and rear ends of the automobile, the large mass block is mounted on the rear end of the motion guiding structure and can perform linear motion along the motion guiding structure, the motion limiting structure is fixedly mounted on the front end of the motion guiding structure and is used to limit the final motion position of the large mass block, the energy absorbing structure is arranged between the motion limiting structure and the large mass block and is used to absorb the motion collision energy of the large mass block, and the force limiting failure structure is connected to the large mass block and is used to fix the large mass block on the motion guiding structure; The motion guide structure includes two chute tracks arranged parallel to the lower end surface of the vehicle chassis longitudinal beam, a plurality of sliding blocks arranged in the chute tracks, and a mounting bracket fixedly connected to each of the sliding blocks. The large mass block is mounted on the mounting bracket. The motion limiting structures are two and are respectively fixedly mounted on the lower end surface of the vehicle chassis longitudinal beam in front of the chute tracks. The energy absorbing structure is two square thin-walled beams, one end of the square thin-walled beam is fixedly mounted on the motion limiting structure, and the other end of the square thin-walled beam faces the large mass block.

2. The vehicle collision energy absorption device according to claim 1, characterized in that: The force-limiting failure structure is a fixing member, which penetrates and connects the sliding block and the slide groove track respectively, and fixes the sliding block in the slide groove track.

3. The vehicle collision energy absorption device according to claim 1, characterized in that: The force-limiting failure structure is the square thin-walled beam, the front end of the square thin-walled beam is fixedly mounted on the motion-limiting structure, and the rear end of the square thin-walled beam extends and is supported on the mounting bracket.

4. The vehicle collision energy absorption device according to claim 1, characterized in that: The inner side surface of the chute track is also paved with a friction material layer, and the friction material layer is in contact with and supported by the sliding block.

5. A method for designing an automobile collision energy absorption device, comprising the following steps: Step 1: The vehicle collision energy absorption device is the vehicle collision energy absorption device according to any one of claims 1 to 4. The collision speed condition that triggers the collision energy absorption of the device is determined to be a collision condition. The vehicle mass M and the collision speed V are set. When the vehicle speed is greater than or equal to V when a collision occurs, the vehicle collision energy absorption device is triggered to operate. Step 2: Determine the collision energy absorbed by the device under collision conditions, and obtain the kinetic energy of the vehicle during collision from the vehicle mass M and collision speed V. The mass of the large mass block is m, and the kinetic energy of the large mass block when it collides is The energy absorption ratio n of the device is determined according to the energy absorption ratio range of the main structural parts of the vehicle, 0<n<1, and the collision energy absorbed by the device is E2=nE, and E2≤E1; Step 3: Design the force limit value of the force failure structure. The force limit value of the force failure structure is to ensure that the force failure structure will not fail to limit the force and trigger the collision energy absorption of the device during emergency braking conditions and low-speed collisions during normal driving. The force limit value is greater than the force on the large mass block under emergency braking conditions, that is, F 限 ≥ma 制动 , F 限 is the force limit value, a 制动 The braking acceleration of the vehicle during emergency braking; Step 4: Design of energy absorbing structure. The energy absorbing structure adopts square thin-walled beams. The energy absorbing structure absorbs energy by collapsing and deforming. The average force of the energy absorbing structure is F. ave =nE / s, s is the effective compression length of the thin-walled closed beam structure. The size, thickness and material of the square thin-walled beam are selected through simulation calculation or theoretical formula calculation. For the square thin-walled beam, F can be calculated by the following formula ave =9.58σ0t 5 / 3 b 1 / 3 , where σ0 is 0.9 to 0.95 times the tensile strength of the square thin-walled beam material, t is the wall thickness of the square thin-walled beam, and b is the side length of the square thin-walled beam or half the sum of the lengths of any two adjacent sides.

6. The method for designing an automobile collision energy absorption device according to claim 5, characterized in that: The force-limiting failure structure is a fixing part, and the force-limiting value is the breaking force of the fixing part.

7. The method for designing an automobile collision energy absorption device according to claim 5, characterized in that: The force-limiting failure structure is a square thin-walled beam, and the force-limiting value is the collision peak load of the square thin-walled beam.

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