A composite leaf spring suspension assembly device with two levels of stiffness

Abstract

The present invention discloses a composite leaf spring suspension assembly device with two-level stiffness, including an FRP composite leaf spring as a secondary spring and a steel leaf spring as a main spring of a steel leaf spring, and also includes an FRP composite leaf spring fixing device, the FRP composite leaf spring fixing device is used to compress the FRP composite leaf spring; a compression riding bolt, the compression riding bolt is straddled on the steel leaf spring, and the studs at both ends of the compression riding bolt face downward; the steel leaf spring is located at the lower side of the FRP composite leaf spring fixing device, and the bottom of the U-shaped end of the compression riding bolt is located at the lower side of the FRP composite leaf spring and connected to the FRP composite leaf spring fixing device. The present invention can fully ensure the stability and safety of the whole vehicle suspension system, while greatly reducing the weight of the leaf spring suspension, realizing the lightweight design of the whole vehicle, increasing the service life of the leaf spring, and improving the fuel efficiency and the smoothness of the vehicle's driving.

Description

Technical Field

[0001] The invention relates to the technical field of non-independent suspension systems for commercial vehicles, and in particular to a composite leaf spring suspension assembly device with two-level stiffness. Background Art

[0002] Suspension is one of the main components of modern cars. It can connect the frame and the axle elastically. Its main task is to transmit all forces and moments acting between the frame and the wheels, and to mitigate the impact load transmitted to the frame due to uneven road surface, attenuate the vibration of the bearing system caused by the impact load, and ensure the normal operation of the car. Among them, the leaf spring is the most widely used elastic element in automobile suspension. According to the different installation positions with the frame, it is divided into front spring and rear spring. In the long-term development process, the leaf spring has become a widely used elastic element in the automobile industry due to its simple structure, low manufacturing cost, small space occupation, and easy maintenance.

[0003] With the development of science and technology, FRP composite leaf springs are gradually used in automobile suspension spring components. The composite materials used in automobile leaf springs are now FRP (Fibre-Reinforced Plastic) composite materials. FRP composite materials have high strength-to-modulus, good fatigue resistance, damping and vibration reduction performance, and corrosion resistance. Therefore, using FRP composite materials as leaf springs can greatly improve the smoothness and comfort of the vehicle, while the mass is only about 1 / 4 of that of steel leaf springs. It not only effectively improves fuel efficiency, but also reduces the unsprung mass and reduces unsprung vibration. At the same time, the service life is more than 3 times that of steel leaf springs. There is no need to replace elastic elements within the life of the vehicle, and the use and maintenance costs of the vehicle are relatively low.

[0004] Now many domestic and foreign automobile manufacturers want to use FRP composite leaf springs to completely replace the existing front and rear suspension leaf springs, such as Fig.11 As shown, however, there are potential safety hazards. Conventional longitudinal leaf springs, in addition to acting as elastic elements that need to transmit the lateral and longitudinal forces and moments of the suspension, also need to have a guiding function and act as a guiding device. They must withstand the ear curling impact, longitudinal torsion and other problems caused by vehicle emergency braking, steering, vertical bouncing and other conditions. During the impact, the movement trajectory of the leaf spring changes, and the axle load is transferred to the front hanging ear and the rear leaf spring produces varying degrees of "S"-shaped distortion. However, because the allowable shear stress of the FRP composite leaf spring is very small, τ≤50Mpa, if the FRP composite leaf spring is directly used to completely replace the leaf spring, especially the rear suspension, the force transmission and guiding functions cannot be met due to the characteristics of the composite material. The ear shear fracture is prone to occur during driving, affecting the safety of the entire vehicle. To solve this problem, some manufacturers still use leaf springs for the main springs and FRP composite leaf springs for the auxiliary springs. Fig.13As shown, the leaf spring and FRP composite leaf spring are fastened in one piece by riding bolts, and the leaf spring pressure plate, FRP composite cover plate, composite material, leaf spring, rear axle housing, and rear axle lower support plate are stacked and fastened in sequence. Taking M20 riding bolts as an example, the locking torque is 450N.M. According to the formula T (torque) = K*F*d, the clamping force F = T / (K*d) = 450 / (0.2*0.2) = 11250N. According to the hardness of FRB resin material, the Barcol hardness HBa = 50, which is converted to Brinell hardness of 32HB. After the pressure plate is pressed, the deformation depth of the composite material is h = 4*F / (32*S) = 4*11250 / (32*70*175) = 0.115mm. Through the analysis of FRP materials, it is found that due to the soft characteristics of composite materials, the soft properties of the composite materials form an obvious "soft connection" feature for the torque after the riding bolts are tightened, and the anisotropic extrusion generated during impact, roll, etc. aggravates the deformation of the composite materials, resulting in a significant attenuation of the riding bolt torque, affecting the clamping effect of the leaf spring assembly and the stability of the suspension system, and affecting the safety of the entire vehicle. Summary of the invention

[0005] The technical problem to be solved by the present invention is to provide a composite leaf spring suspension assembly device with two-level stiffness. The present invention can fully guarantee the life and safety of the suspension, while greatly reducing the weight of the leaf spring suspension, realizing a lightweight design of the entire vehicle, increasing the service life of the leaf spring, and improving fuel efficiency and the smoothness of vehicle driving.

[0006] In order to solve the above technical problems, the technical solution of the present invention is: a composite leaf spring suspension assembly device with two levels of stiffness, including an FRP composite leaf spring as a secondary spring and a steel leaf spring as a main spring, and also including

[0007] An FRP composite leaf spring fixing device, wherein the FRP composite leaf spring fixing device is used to compress the FRP composite leaf spring;

[0008] A clamping bolt, wherein the clamping bolt is straddled on the leaf spring, and the studs at both ends of the clamping bolt face downwards;

[0009] The leaf spring is located at the lower side of the FRP composite leaf spring fixing device, and the bottom of the U-shaped end of the compression riding bolt is located at the lower side of the FRP composite leaf spring and connected to the FRP composite leaf spring fixing device.

[0010] As an optimal technical solution, the FRP composite leaf spring fixing device includes an upper cover plate and a lower cover plate respectively located on the upper and lower sides of the middle part of the FRP composite leaf spring, the lower surface of the upper cover plate is provided with an upper constraint groove for constraining the upper part of the middle part of the FRP composite leaf spring, and the upper surface of the lower cover plate is provided with a lower constraint groove for constraining the lower part of the middle part of the FRP composite leaf spring, the sum of the groove depths of the upper constraint groove and the lower constraint groove is less than the thickness of the middle part of the FRP composite leaf spring; and the middle part of the FRP composite leaf spring is higher than the groove depth of the lower constraint groove, so that after the FRP composite leaf spring is placed in the lower constraint groove, its middle section is higher than the groove depth of the lower constraint groove, the upper cover plate is covered, and there is a gap between the upper cover plate and the lower cover plate after they are fixed, and a clamping connection device is provided between the upper cover plate and the lower cover plate; the middle part of the clamping riding bolt is connected to the lower cover plate.

[0011] As a preferred technical solution, an upper limit column and a lower limit column are respectively protruding from the upper and lower sides of the middle part of the FRP composite leaf spring, an upper limit hole corresponding to the upper limit column is provided on the bottom of the upper constraint groove of the upper cover plate, and a lower limit hole corresponding to the lower limit column is provided on the bottom of the lower constraint groove of the lower cover plate.

[0012] As a preferred technical solution, the FRP composite leaf spring includes a FRP composite leaf spring middle section, both ends of which are bent upward and extended to provide variable cross-section sections, and the upper cover plate and the lower cover plate are located in the FRP composite leaf spring middle section.

[0013] As a preferred technical solution, a wear-resistant plate is bonded to the upper surface of the outer end of the variable-section segment, and a countersunk screw is connected between the wear-resistant plate and the variable-section segment.

[0014] As a preferred technical solution, the clamping connection device includes bolt holes respectively arranged at the four corners of the upper cover plate, the lower cover plate is provided with internal threaded holes corresponding to the bolt holes, and flange bolts are connected to the bolt holes and the internal threaded holes.

[0015] As a preferred technical solution, clamping plates are protruding from both ends of the bottom of the lower cover plate, and a clamping groove is provided on the clamping plate. The clamping bolts are respectively provided on both sides of the lower cover plate, and the bottoms of the U-shaped ends of the two clamping bolts are respectively provided in the corresponding clamping grooves.

[0016] As a preferred technical solution, the clamping bolt is alloy round steel, and the bottom of the U-shaped end of the clamping bolt is a forged flat structure that has been forged and tempered, and the shape of the bottom of the U-shaped end of the clamping bolt fits closely with the clamping groove.

[0017] As a preferred technical solution, the FRP composite leaf spring is an equal-width FRP composite plate structure formed by a high-pressure resin transfer molding process.

[0018] A composite leaf spring suspension assembly with two levels of stiffness adopting the above technical solution comprises an FRP composite leaf spring as an auxiliary spring and a steel leaf spring as a main spring, and also comprises an FRP composite leaf spring fixing device, wherein the FRP composite leaf spring fixing device is used to compress the FRP composite leaf spring; a compression riding bolt, wherein the compression riding bolt is straddled on the steel leaf spring, and the studs at both ends of the compression riding bolt face downward; the steel leaf spring is located at the lower side of the FRP composite leaf spring fixing device, and the bottom of the U-shaped end of the compression riding bolt is located at the FRP composite leaf spring. The lower side of the composite material leaf spring is connected to the FRP composite material leaf spring fixing device; the present invention replaces the existing auxiliary spring steel leaf spring with an FRP composite material leaf spring, and the main spring still uses a steel leaf spring. Considering the low allowable shear strength and softness of the FRP composite material leaf spring, the structure is optimized according to the force of the FRP composite material leaf spring, and the riding bolt is adjusted from the conventional steel leaf spring and FRP composite material leaf spring unified clamping mode to the FRP composite material leaf spring being compressed by the FRP composite material leaf spring fixing device, and the compressed riding bolt only clamps the steel leaf spring. The technical solution of the present invention brings the following beneficial effects:

[0019] 1. FRP composite leaf springs will not break all at once, ensuring the safety of vehicle driving; conventionally made of prepreg with epoxy resin as the matrix material and glass fiber as the reinforcement material, the fatigue life of FRP composite leaf springs is generally more than 500,000 times;

[0020] 2. Greatly reduce the weight of leaf spring suspension, realize lightweight design of the whole vehicle, and greatly improve fuel efficiency and vehicle driving smoothness;

[0021] 3. Improve the structure of FRP composite leaf springs and metal connectors, improve the reliability of FRP composite leaf springs, and increase the life of longitudinal leaf spring suspensions to more than 5 times that of longitudinal steel leaf springs. There is no need to replace elastic elements such as leaf springs within the service life of the vehicle, which greatly reduces the cost of leaf springs.

[0022] 4. By using the FRP composite leaf spring fixing device to compress and tighten the riding bolts to only clamp the leaf spring, the torque attenuation during the clamping process of the riding bolts can be effectively avoided, ensuring that the leaf spring improves the overall stability of the suspension. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The following drawings are intended only to illustrate and explain the present invention, and are not intended to limit the scope of the present invention.

[0024] Figure 1 It is a schematic diagram of the structure of the present invention;

[0025] Figure 2 It is a schematic diagram of the installation of the present invention;

[0026] Figure 3 is a schematic diagram of an FRP composite leaf spring of the present invention;

[0027] Figure 4 is a top view of the FRP composite leaf spring of the present invention;

[0028] Figure 5 is a schematic diagram of a wear-resistant plate of the present invention;

[0029] Figure 6 It is a schematic diagram of the upper cover plate of the present invention;

[0030] Figure 7 is a top view of the upper cover plate of the present invention;

[0031] Figure 8 is a schematic diagram of the lower cover plate of the present invention;

[0032] Fig. 9 It is a schematic diagram of a compression riding bolt of the present invention;

[0033] Fig.10 It is a schematic diagram of the installation of the compression riding bolt of the present invention;

[0034] Fig.11 It is a schematic diagram of completely replacing the suspension leaf spring with the FRP composite leaf spring in the prior art;

[0035] Fig.12 It is a schematic diagram of the stress deformation after the suspension leaf spring is completely replaced by the FRP composite leaf spring in the prior art;

[0036] Fig.13 It is a schematic diagram of a steel leaf spring for a main spring and an FRP composite leaf spring for a secondary spring in the prior art;

[0037] Fig.14 It is a schematic diagram of a steel leaf spring for main spring and an FRP composite leaf spring for auxiliary spring in the prior art before road testing;

[0038] Fig.15 It is a schematic diagram of a steel leaf spring for main spring and an FRP composite leaf spring for auxiliary spring in the prior art after road testing.

[0039] In the figure: 1-FRP composite leaf spring; 11-FRP composite leaf spring middle section; 12-variable section; 13-wear-resistant plate; 14-upper limit column; 15-lower limit column; 16-countersunk screw; 2-steel leaf spring; 3-tensioning bolt; 31-stud; 32-U-shaped end bottom; 4-upper cover; 41-upper limit hole; 42-bolt hole; 43-upper constraint groove; 5-lower cover; 51-lower limit hole; 52-internal thread hole; 53-lower constraint groove; 54-tensioning plate; 55-tensioning groove; 6-rear axle; 61-rear axle lower support plate; 7-vehicle beam; 71-limiting block; 72-leaf spring bracket. DETAILED DESCRIPTION

[0040] Hereinafter, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. It should be noted that, in the accompanying drawings, the same reference numerals are given to components having substantially the same structure and function, and redundant descriptions of substantially the same components are omitted to make the specification more concise.

[0041] like Fig.11 As shown, many automobile manufacturers at home and abroad now use FRP composite leaf springs 1 to completely replace the existing leaf springs of the suspension as the main spring and auxiliary spring. The main spring and the auxiliary spring are fastened in an integrated manner, and the leaf spring pressure plate, the FRP composite leaf spring 1 and the rear axle 6 and other components are stacked and fastened. Because when the vehicle is running, the conventional longitudinal leaf spring not only plays the role of an elastic element and needs to transmit the lateral and longitudinal forces and moments of the suspension, but also needs to have a guiding function and also serve as a guiding device, and withstand the problems of ear impact and longitudinal torsion caused by emergency braking, steering, vertical bouncing, etc. of the vehicle. Because the front end of the FRP composite leaf spring 1 is connected to the leaf spring bracket 72 on the vehicle beam 7 through the ear and the pin shaft to form a fixed hinge fulcrum, which is a fixed end and plays the role of force transmission and guidance; and the rear end of the FRP composite leaf spring 1 is connected to the leaf spring bracket 72 on the vehicle beam 7 through the ear, the hanging ear and the pin shaft to form a swinging hinge fulcrum, which is a movable end, to ensure that the distance between the center lines of the two ears of the FRP composite leaf spring 1 may change when the deformation of the FRP composite leaf spring 1 occurs. Fig.12As shown in the figure, the movement trajectory of the FRP composite leaf spring 1 changes during the impact process of the vehicle. After the axle load is transferred to the front side, the FRP composite leaf spring 1 produces different degrees of "S"-shaped distortion, and the rear end of the FRP composite leaf spring 1 moves forward a, while the center point between the two ears of the FRP composite leaf spring 1 moves from point d to point d', and the distance between the front end of the FRP composite leaf spring 1 and the center point between the two ears of the FRP composite leaf spring 1 shrinks from b to b'. However, since the allowable shear stress of the FRP composite leaf spring 1 is very small, τ≤50Mpa, if the FRP composite leaf spring 1 is directly used to completely replace the steel leaf spring 2, especially the rear suspension, the composite material characteristics cannot meet the force transmission and guidance functions, and the ear shear fracture is prone to occur during the driving process of the vehicle, affecting the safety of the whole vehicle.

[0042] like Fig.13 As shown, existing manufacturers still use a steel leaf spring 2 as the main spring and an FRP composite leaf spring 1 as the auxiliary spring. The steel leaf spring and the FRP composite leaf spring are fastened in an integrated manner, and the leaf spring pressure plate, the composite cover plate, the FRP composite leaf spring 1, the steel leaf spring 2, the rear axle 6 housing, and the rear axle lower support plate 61 are stacked and fastened in sequence by riding bolts. However, due to the soft characteristics of the composite material, its soft characteristics form an obvious "soft connection" feature for the torque after the riding bolts are fastened, and the asymmetric extrusion generated during impact, roll, etc. aggravates the deformation of the composite material, resulting in a significant attenuation of the riding bolt torque, affecting the clamping effect of the leaf spring assembly and the stability of the suspension system, and affecting the safety of the entire vehicle.

[0043] A two-stage rigidity composite leaf spring suspension assembly device of the present invention, such as Figure 1 and Figure 2 As shown, it includes an FRP composite leaf spring 1 as an auxiliary spring and a steel leaf spring 2 as a main spring. The steel leaf spring 2 can be a leaf spring.

[0044] An FRP composite leaf spring fixing device, wherein the FRP composite leaf spring fixing device is used to compress the FRP composite leaf spring 1;

[0045] A clamping bolt 3, wherein the clamping bolt 3 is straddled on the leaf spring 2, and the studs 31 at both ends of the clamping bolt 3 face downwards;

[0046] The leaf spring 2 is located at the lower side of the FRP composite leaf spring fixing device, and the U-shaped end bottom 32 of the compression riding bolt 3 is located at the lower side of the FRP composite leaf spring 1 and connected to the FRP composite leaf spring fixing device.

[0047] Considering the low permissible shear strength and softness of the FRP composite leaf spring 1, the structure is optimized according to the magnitude of the force on the FRP composite leaf spring 1, the FRP composite leaf spring 1 as the auxiliary spring is compressed by the FRP composite leaf spring fixing device, and then the compression riding bolt 3 is compressed and connected to the FRP composite leaf spring fixing device and the steel leaf spring 2 as the main spring is clamped, and then the compression riding bolt 3 is installed on the rear axle 6 in cooperation with the rear axle lower support plate 61, and the front end of the steel leaf spring 2 as the main spring is connected to the leaf spring bracket 72 on the vehicle beam 7 through the coil ear and the pin shaft to form a fixed hinge fulcrum, and the rear end of the leaf spring is connected to the leaf spring bracket 72 on the vehicle beam 7 through the coil ear, the hanging ear and the pin shaft to form a swing hinge fulcrum, and the connection method of the front and rear ends of the steel leaf spring 2 is a well-known conventional technology. The FRP composite leaf spring 1 can be an equal-width FRP composite plate structure formed by a high-pressure resin transfer molding process.

[0048] like Figures 1 to 8As shown, the FRP composite leaf spring fixing device includes an upper cover plate 4 and a lower cover plate 5 respectively located at the upper and lower sides of the middle part of the FRP composite leaf spring 1, the lower surface of the upper cover plate 4 is provided with an upper constraint groove 43 for constraining the upper part of the middle part of the FRP composite leaf spring 1, and the upper surface of the lower cover plate 5 is provided with a lower constraint groove 53 for constraining the lower part of the middle part of the FRP composite leaf spring 1. The sum of the groove depths of the upper constraint groove 43 and the lower constraint groove 53 is less than the thickness of the middle part of the FRP composite leaf spring 1, and the middle part of the FRP composite leaf spring 1 is higher than the groove depth of the lower constraint groove 53. In this way, after the FRP composite leaf spring 1 is placed in the lower constraint groove 53, its middle section is higher than the groove depth of the lower constraint groove 53, and the upper cover plate 4 is covered. There is a gap between the upper cover plate 4 and the lower cover plate 5 after they are fixed, and a clamping connection device is provided between the upper cover plate 4 and the lower cover plate 5; the middle part of the clamping riding bolt 3 is connected to the lower cover plate 5. The upper cover plate 4 and the lower cover plate 5 can be cast, normalized, shot peened, and rust-proof painted on the surface; the clamping connection device includes bolt holes 42 at the four corners of the upper cover plate 4, and the lower cover plate 5 is provided with internal threaded holes 52 corresponding to the bolt holes 42, and flange bolts are connected in the bolt holes 42 and the internal threaded holes 52. The upper restraint groove 43 and the lower restraint groove 53 are approximately at the upper and lower sides of the middle of the FRP composite leaf spring 1, and the upper cover plate 4 and the lower cover plate 5 are connected and fastened by flange bolts, so that the FRP composite leaf spring 1 is firmly restrained and fastened between the upper cover plate 4 and the lower cover plate 5; the upper and lower sides of the middle of the FRP composite leaf spring 1 are respectively protruded with upper limit columns 14 and lower limit columns 15, and the groove bottom of the upper restraint groove 43 of the upper cover plate 4 is provided with an upper limit hole 41 corresponding to the upper limit column 14, and the groove bottom of the lower restraint groove 53 of the lower cover plate 5 is provided with a lower limit hole 51 corresponding to the lower limit column 15, and the upper limit column 14 cooperates with the upper limit hole 41, and the lower limit column 15 cooperates with the lower limit hole 51, so that the mutual movement between the upper cover plate 4 and the lower cover plate 5 and the FRP composite leaf spring 1 is prevented, thereby protecting the FRP composite leaf spring 1. The FRP composite leaf spring 1 includes a FRP composite leaf spring middle section 11, and both ends of the FRP composite leaf spring middle section 11 are bent and extended upward to be provided with variable cross-section sections 12. The upper cover plate 4 and the lower cover plate 5 are located at the FRP composite leaf spring middle section 11, so that the upper limit column 14 and the lower limit column 15 are both located at the upper and lower sides of the middle section of the FRP composite leaf spring 11, which plays a balancing role in the fastening and supporting force of the FRP composite leaf spring 1.A wear-resistant plate 13 is bonded to the upper surface of the outer end of the variable-section segment 12, and a countersunk screw 16 is also connected between the wear-resistant plate 13 and the variable-section segment 12; the wear-resistant plate 13 can be selected as an alloy steel plate and the surface is quenched, one side of the wear-resistant plate 13 is glued to the upper surface of the outer end of the variable-section segment 12, and the other side of the wear-resistant plate 13 is punched and fastened to the outer end of the variable-section segment 12 of the FRP composite leaf spring 1 with a countersunk screw 16, and works in conjunction with the limit block 71 on the vehicle beam 7. The two ends of the bottom of the lower cover plate 5 are respectively protruded with clamping plates 54, and the two clamping plates 54 extend in the front and rear directions of the lower cover plate 5, respectively. The clamping plates 54 are provided with clamping grooves 55. The clamping riding bolts 3 are respectively provided on both sides of the lower cover plate 5, and the U-shaped end bottoms 32 of the two clamping riding bolts 3 are respectively arranged in the corresponding clamping grooves 55. In this way, the FRP composite leaf spring 1 is firmly constrained and compressed by the upper cover plate 4, the lower cover plate 5 and the flange bolts, and the clamping riding bolts 3 cooperate with the clamping grooves 55 on the lower cover plate 5 and clamp the leaf spring 2 and then install it on the rear axle 6, realizing the leaf spring The split clamping assembly method of the steel leaf spring 2 and the FRP composite leaf spring 1 avoids the breakage of the FRP composite leaf spring 1 caused by longitudinal torsion, deformation and twisting due to the transmission of suspension lateral and longitudinal forces and moments, guidance, emergency braking, steering, vertical bouncing and other conditions of the vehicle during driving, thereby ensuring the safety of the entire vehicle; at the same time, it also avoids the deformation of the FRP composite leaf spring 1 due to axial extrusion caused by impact, roll and the like caused by the integrated fastening of the steel leaf spring 2 and the FRP composite leaf spring 1, thereby avoiding a significant attenuation of the riding bolt torque and ensuring the clamping effect of the leaf spring assembly and the stability of the suspension system.

[0049] like Fig. 9 and Fig.10 As shown, the clamping bolt 3 is alloy round steel, and the bottom 32 of the U-shaped end of the clamping bolt 3 is a forged flat structure that has been forged and tempered. The shape of the bottom 32 of the U-shaped end of the clamping bolt 3 is closely matched with the clamping groove 55. The forging flattening process can effectively ensure that the clamping bolt 3 is matched with the clamping groove 55 on the lower cover plate 5, thereby effectively clamping the leaf spring 2.

[0050] The clamping bolt 3 of the present invention only fastens the leaf spring 2 and the rear axle 6. The U-shaped bottom 32 of the clamping bolt 3 adopts a forged flat structure, which effectively ensures the clamping torque of the clamping bolt 3. The existing method of fastening the leaf spring and FRP composite leaf spring in one piece with the existing method of clamping the leaf spring and FRP composite leaf spring in separate pieces with the present invention is tested on a professional test field. Fig.14As shown, it is a schematic diagram of the prior art that the main spring uses a steel leaf spring 2 and the auxiliary spring uses an FRP composite leaf spring 1 before the road test. In the figure, the steel leaf spring 2 and the FRP composite leaf spring 2 are both in a normal state. The torque attenuation and suspension component status after the road test are compared as shown in the following table:

[0051]

[0052] After a professional road comparison test of 800km of Belgian roads, 800km of washboard roads and 400km of twisted roads, a total of 2000km, the vehicle assembly of the two types of leaf springs 2 and FRP composite leaf springs 1 under the action of alternating loads, the leaf springs 2 and FRP composite leaf springs 1 undergo high-frequency deflection changes, and the riding bolts of the suspension all experience obvious torque attenuation. The suspension components of the two types of leaf springs 2 and FRP composite leaf springs 1 are disassembled and analyzed, and the experimental data are shown in the table above. Through comparative analysis of the experimental data in the table above, the torque attenuation amplitude of the compression riding bolt 3 of the split fastening leaf spring 2 and FRP composite leaf spring 1 of the present invention is 14.45 percentage points lower than that of the traditional existing riding bolt integrated fastening leaf spring 2 and FRP composite leaf spring 1 structure. The average torque of the compression riding bolt 3 of the present invention after attenuation basically meets the torque lower limit standard of the M20*1.5 riding bolt and can continue to be used, and can still effectively ensure the clamping effect of the leaf spring assembly and the stability of the suspension system, and ensure the safety of the whole vehicle. However, the existing integrated riding bolts for fastening the main spring steel leaf spring and the auxiliary spring FRP composite leaf spring have obvious torque attenuation, and the auxiliary spring FRP composite leaf spring 1 has been obviously skewed, such as Fig.15 As shown, it is a schematic diagram of the prior art in which a main spring uses a steel leaf spring 2 and an auxiliary spring uses an FRP composite leaf spring 1 after a road test. In the figure, the end of the FRP composite leaf spring 1 interferes significantly with the vehicle beam 7, and the main material of the FRP composite leaf spring 1 is worn and wire-drawn, and the FRP composite leaf spring 1 can no longer be used.

[0053] As mentioned above, the embodiments of the present invention have been specifically described above, but the present invention is not limited thereto. It should be understood by those skilled in the art that various modifications, combinations, sub-combinations or substitutions can be made according to design requirements or other factors, and they are within the scope of the appended claims and their equivalents.

Claims

1. A composite leaf spring suspension assembly with two levels of stiffness, comprising an FRP composite leaf spring as a secondary spring and a steel leaf spring as a main spring, characterized in that: Also includes An FRP composite leaf spring fixing device, wherein the FRP composite leaf spring fixing device is used to compress the FRP composite leaf spring; A clamping bolt, wherein the clamping bolt is straddled on the leaf spring, and the studs at both ends of the clamping bolt face downwards; The leaf spring is located at the lower side of the FRP composite leaf spring fixing device, and the bottom of the U-shaped end of the compression riding bolt is located at the lower side of the FRP composite leaf spring and connected to the FRP composite leaf spring fixing device; The FRP composite leaf spring fixing device comprises an upper cover plate and a lower cover plate respectively located at the upper and lower sides of the middle part of the FRP composite leaf spring, the lower surface of the upper cover plate is provided with an upper constraint groove for constraining the upper part of the middle part of the FRP composite leaf spring, the upper surface of the lower cover plate is provided with a lower constraint groove for constraining the lower part of the middle part of the FRP composite leaf spring, the sum of the groove depths of the upper constraint groove and the lower constraint groove is less than the thickness of the middle part of the FRP composite leaf spring, and the middle part of the FRP composite leaf spring is higher than the groove depth of the lower constraint groove, a clamping connection device is provided between the upper cover plate and the lower cover plate; the middle part of the clamping riding bolt is connected to the lower cover plate; An upper limit post and a lower limit post are respectively protruded on the upper and lower sides of the middle part of the FRP composite leaf spring, an upper limit hole corresponding to the upper limit post is provided on the bottom of the upper constraint groove of the upper cover plate, and a lower limit hole corresponding to the lower limit post is provided on the bottom of the lower constraint groove of the lower cover plate; The clamping connection device comprises bolt holes respectively arranged at the four corners of the upper cover plate, the lower cover plate is provided with internal thread holes corresponding to the bolt holes, and flange bolts are connected in the bolt holes and the internal thread holes; The two ends of the bottom of the lower cover plate are respectively protruded with clamping plates, and the clamping plates are provided with clamping grooves. The clamping riding bolts are respectively provided on both sides of the lower cover plate, and the bottoms of the U-shaped ends of the two clamping riding bolts are respectively arranged in the corresponding clamping grooves.

2. A two-stage stiffness composite leaf spring suspension assembly device as claimed in claim 1, characterized in that: The FRP composite leaf spring comprises a middle section of the FRP composite leaf spring, both ends of which are bent upward and extended to form variable cross-section sections, and the upper cover plate and the lower cover plate are located at the middle section of the FRP composite leaf spring.

3. A two-stage stiffness composite leaf spring suspension assembly device as claimed in claim 2, characterized in that: A wear-resistant plate is bonded to the upper surface of the outer end of the variable-section segment, and a countersunk screw is connected between the wear-resistant plate and the variable-section segment.

4. A two-stage rigidity composite leaf spring suspension assembly device as claimed in claim 1, characterized in that: The clamping riding bolt is made of alloy round steel, and the bottom of the U-shaped end of the clamping riding bolt is a forged flat structure that has been forged and tempered. The shape of the bottom of the U-shaped end of the clamping riding bolt is closely matched with the clamping groove.

5. A two-stage rigidity composite leaf spring suspension assembly as claimed in any one of claims 1 to 4, characterized in that: The FRP composite material leaf spring is an equal-width FRP composite material plate-shaped structure formed by a high-pressure resin transfer molding process.

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