Rigidity-adjustable steel plate spring assembly

Abstract

The invention belongs to the technical field of suspension systems, and particularly relates to a rigidity-adjustable steel plate spring assembly which comprises a main spring, an auxiliary spring, an auxiliary plate spring, a first cushion block, a second cushion block, an adjusting assembly and a center bolt. According to the rigidity-adjustable steel plate spring assembly, the acting point of the auxiliary spring or the auxiliary plate spring can be adjusted according to needs, and a rigidity curve is changed from a fixed state to an adjustable state. During no-load and in the suspension movement process, the auxiliary spring makes contact later, the auxiliary plate spring does not make contact, the suspension works normally, only the rigidity of the main spring acts, the rigidity is low, comfort is fully guaranteed, the auxiliary spring acts only during large displacement, and the suspension and a vehicle body are effectively protected. And the auxiliary spring or the auxiliary plate spring works in advance during full load, so that the comfort and the bearing performance are both considered. During overload, the auxiliary spring further acts in advance and even directly contacts with the main spring, the acting point of the auxiliary plate spring is advanced, the rigidity of the steel plate spring is greatly improved, and the bearing performance is improved.

Description

Technical Field

[0001] The invention belongs to the technical field of suspension systems, and in particular relates to a leaf spring assembly with adjustable stiffness. Background Art

[0002] Leaf springs are a common elastic element in automotive suspension systems. They are primarily composed of multiple spring steel sheets of unequal lengths stacked together. They are named for their leaf-like shape and the elastic properties of springs. Leaf springs are typically curved and installed between the axle and frame of a vehicle using components such as U-bolts. During driving, leaf springs utilize their elastic deformation to cushion and absorb impact and vibration from the road, thereby ensuring smooth and stable driving. They also transmit vertical, driving, braking, and lateral forces, and provide guidance, ensuring the correct relative motion between the axle and frame.

[0003] Currently, leaf springs are divided into single-rigidity leaf springs and segmented-rigidity leaf springs.

[0004] A single-strength leaf spring is one whose stiffness remains constant regardless of load. It typically consists of multiple spring steel leaves of equal width but unequal length, stacked together. The leaves can have varying thicknesses. During assembly, the leaves are secured together with a central bolt or other fastening method, forming a nearly uniformly strong elastic beam. The spring's ends are connected to the vehicle's frame and axle using coil eyes, hanging eyes, or other fastening devices.

[0005] The advantages of single-strength leaf springs are simple structure, easy design and manufacturing, and relatively low cost. They are reliable and can function stably under various harsh road conditions and usage conditions. They also have a strong load-bearing capacity and can meet the vehicle's support requirements under the designed load. However, their disadvantages are that their stiffness is not variable, making it difficult to balance comfort and handling when the vehicle is unloaded or fully loaded. When unloaded or lightly loaded, the high spring stiffness can cause significant vehicle vibration and poor comfort. When fully loaded or heavily loaded, spring deformation may affect the vehicle's handling.

[0006] The segmented stiffness leaf spring is a special type of leaf spring used in automobile suspension systems. Through different designs and structures, it achieves segmented changes in stiffness to meet the needs of the vehicle under different loads. Common leaf springs include two-stage stiffness and three-stage stiffness. The following is a detailed introduction: Two-stage stiffness leaf spring: generally composed of independent main springs and auxiliary springs. When the vehicle is unloaded, the rear axle load is small, and only the main spring works. At this time, the main spring stiffness is the first level stiffness; when the vehicle is fully loaded, the rear axle load is large, and the main spring and auxiliary spring work together. The sum of the main spring stiffness and the auxiliary spring stiffness is the second level stiffness. Three-stage stiffness leaf spring: includes main springs, auxiliary springs and auxiliary leaf springs. When unloaded, only the main spring is active, achieving a first-level stiffness. When fully loaded, the main and auxiliary springs work together, with the combined stiffness of the main and auxiliary springs forming the second-level stiffness. When the vehicle is heavily loaded (overloaded), the rear axle is subjected to a greater load, and the main, auxiliary, and auxiliary leaf springs all work together, with the combined stiffness forming the third-level stiffness. The advantage of segmented leaf springs is that they can accommodate the vehicle's performance requirements under varying loads. When unloaded or lightly loaded, they provide greater comfort with lower stiffness. When fully loaded or heavily loaded, they increase stiffness to ensure the vehicle's load-bearing capacity and driving stability, effectively reducing overall vehicle vibration. However, their structure is more complex than that of ordinary leaf springs, making them more difficult to design and manufacture, and potentially more expensive. The auxiliary spring or auxiliary leaf spring of the existing stiffness segmented leaf spring has a fixed acting point and a fixed stiffness curve. When it is unloaded and in the process of jumping up, the main spring will contact the auxiliary spring or auxiliary leaf spring, the stiffness will increase, and the comfort will decrease. When it is fully loaded or overloaded, the main spring, auxiliary spring or auxiliary leaf spring will contact later and the load-bearing capacity will be poor. Summary of the Invention

[0007] The purpose of the present invention is to provide a leaf spring assembly with adjustable stiffness, which can adjust the action point of the auxiliary spring or auxiliary leaf spring as needed, so that the stiffness curve changes from fixed to adjustable. When unloaded, the auxiliary spring contacts later during the movement of the suspension, and the auxiliary leaf spring does not contact. The suspension works normally, and only the stiffness of the main spring is effective, which is relatively low and fully guarantees comfort. The auxiliary spring only acts during large displacements, effectively protecting the suspension and the vehicle body. When fully loaded, the action point of the auxiliary spring or auxiliary leaf spring is advanced, taking into account both comfort and load-bearing performance. When overloaded, the auxiliary spring acts further in advance and even directly contacts the main spring. The action point of the auxiliary leaf spring is also advanced, which greatly increases the stiffness of the leaf spring and improves the load-bearing performance.

[0008] To achieve the above objectives, this application is implemented through the following technical solutions:

[0009] A stiffness-adjustable leaf spring assembly comprises a main spring, a secondary spring, an auxiliary leaf spring, a first pad, a second pad, an adjustment component and a center bolt;

[0010] The main spring, the first pad, the auxiliary spring, the second pad, and the auxiliary leaf spring are arranged in sequence from top to bottom and fixed by a central bolt. Adjustment components are respectively provided at both ends of the auxiliary spring.

[0011] Furthermore, the main spring, auxiliary spring and auxiliary leaf spring are each composed of a single or multiple spring steel sheets, and the widths of the spring steel sheets of the main spring, the auxiliary spring and the auxiliary leaf spring are all equal.

[0012] Furthermore, the cross-section of each spring steel sheet in the length direction is a constant cross-section and / or a variable cross-section, the widths of the spring steel sheets are equal, the thicknesses of the spring steel sheets are the same or different, and the lengths of the spring steel sheets are equal or different.

[0013] Furthermore, a front coil ear and a rear coil ear are respectively provided at both ends of the first spring steel sheet of the main spring for mounting a spring pin.

[0014] Furthermore, the length from the center bolt hole to the front end of each spring steel sheet of the main spring is smaller than the length from the center bolt hole to the rear end, and the curvature from the center bolt hole to the front end is smaller than the curvature from the center bolt hole to the rear end.

[0015] Furthermore, noise reduction pads are provided at the contact positions of the spring steel sheets of the main spring.

[0016] Furthermore, a mounting hole is provided near both ends of the uppermost spring steel plate of the auxiliary spring for mounting an adjustment assembly.

[0017] Furthermore, the adjustment assembly is composed of an adjustment pad assembly, a screw assembly and a nut. The adjustment pad assembly is composed of an adjustment pad and an external hexagonal boss arranged below the adjustment pad. A central threaded hole is provided on the external hexagonal boss, and the central threaded hole is threadedly engaged with the threaded rod of the screw assembly.

[0018] The screw assembly includes a threaded rod, an external hexagonal support plate and a circular tube portion. A threaded hole is provided in the center of the external hexagonal support plate, and an internal thread is provided on the inner side surface of the circular tube portion. One end of the circular tube portion is fixedly connected to the external hexagonal support plate. The external hexagonal support plate and the circular tube portion are threadedly connected to the threaded rod, and the circular tube portion cooperates with the mounting hole on the auxiliary spring.

[0019] Furthermore, a nut is provided at each end of the threaded rod.

[0020] The beneficial effects of the present invention are:

[0021] The stiffness-adjustable leaf spring assembly of the present application can adjust the action point of the auxiliary spring or auxiliary leaf spring as needed, so that the stiffness curve changes from fixed to adjustable. When unloaded, the auxiliary spring contacts later during the movement of the suspension, and the auxiliary leaf spring does not contact. The suspension works normally, and only the stiffness of the main spring takes effect, which is relatively low and fully guarantees comfort. The auxiliary spring only takes effect during large displacements, effectively protecting the suspension and the vehicle body. When fully loaded, the action point of the auxiliary spring or auxiliary leaf spring is advanced, taking into account both comfort and load-bearing performance. When overloaded, the auxiliary spring acts further in advance and even directly contacts the main spring. The action point of the auxiliary leaf spring is also advanced, which greatly increases the stiffness of the leaf spring and improves the load-bearing performance. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 This is a schematic diagram of the structure of the stiffness-adjustable leaf spring assembly of the present invention.

[0023] Figure 2 It is a schematic diagram of the main spring structure of the present invention.

[0024] Figure 3 Schematic diagram of the auxiliary spring structure of the present invention.

[0025] Figure 4 It is a schematic diagram of the cushion block structure of the present invention.

[0026] Figure 5 This is a schematic diagram of the component structure adjustment of the present invention.

[0027] Figure 6 Schematic diagram of the adjustment pad assembly structure.

[0028] Figure 7 Schematic diagram of the screw assembly structure.

[0029] Description of reference numerals:

[0030] 10. Main spring; 12. First spring steel sheet; 14. Front ear; 16. Rear ear; 15. Front bushing; 18. Noise reduction pad; 20. Auxiliary spring; 22. Mounting hole; 24. Center hole; 30. First spacer; 40. Auxiliary leaf spring; 50. Second spacer; 60. Adjustment assembly; 62. Nut; 70. Center bolt; 80. Adjustment pad assembly; 82. Adjustment pad; 84. External hexagonal boss; 86. Center threaded hole; 90. Screw assembly; 92. Threaded rod; 94. External hexagonal support plate; 96. Circular tube. DETAILED DESCRIPTION

[0031] The technical solution of the present invention is described in detail below with reference to the accompanying drawings. The following embodiments are merely exemplary and can only be used to explain and illustrate the technical solution of the present invention, and cannot be interpreted as limiting the technical solution of the present invention.

[0032] like Figures 1 to 7As shown, the present application provides a stiffness-adjustable leaf spring assembly, which consists of a main spring 10 , a secondary spring 20 , an auxiliary leaf spring 40 , a first pad 30 , a second pad 50 , an adjustment assembly 60 and a center bolt 70 .

[0033] The main spring 10, first pad 30, auxiliary spring 20, second pad 50 and auxiliary leaf spring 40 of the present application are arranged in sequence from top to bottom and fixed by a central bolt 70. An adjustment assembly 60 is provided at each end of the auxiliary spring 20.

[0034] The main spring 10 of the present application can be a single spring steel sheet or composed of multiple spring steel sheets stacked one above the other, depending on the vehicle model or design requirements. In other embodiments of the present application, composite spring sheets can also be used instead. In the present application, if composed of multiple spring steel sheets, the width of each spring steel sheet should be equal. Specifically, when the spring steel sheets are stacked one above the other, the width at each position should be equal. The thickness of each spring steel sheet can be the same or different depending on the design requirements, and the length of each spring steel sheet (along the length direction of the vehicle) can be equal or unequal. In addition, the cross-sectional area of ​​each spring steel sheet at different positions along the length direction of the present application is equal or unequal.

[0035] The front and rear ears 14 and 16 are located at the front and rear ends of the first spring leaf 12 (topmost) of the main spring. These ears are used to receive spring pins, connecting to the brackets or lugs, thus connecting the leaf spring to the vehicle frame and axle, enabling the leaf spring to perform its cushioning, vibration reduction, and force transmission functions. The front ear 14 is typically press-fitted onto the leaf spring's front bushing 15 to cushion impact forces. Noise-damping pads 18 can be added to the contact points between the leaf spring leaves to reduce friction and noise.

[0036] In the present application, the length from the center bolt hole of each spring steel sheet of the main spring to the front end is shorter than the length from the center bolt hole to the rear end, and the curvature from the center bolt hole to the front end is shorter than the curvature from the center bolt hole to the rear end. Such a structural arrangement can meet the needs of the vehicle whether it is empty or fully loaded, because the center of gravity of the vehicle is located between the rear wheels and the front wheels, that is, the force on the front part of the leaf spring is greater than the force on the rear end. Therefore, when the front end length of the main spring is shorter than the rear end length, the supporting force it bears is significantly improved. At the same time, in order to ensure the vibration reduction performance, the curvature of the front end is reduced, that is, the degree of bending is increased to ensure the vibration reduction effect.

[0037] In this application, the structure of the auxiliary spring 20 is similar to that of the main spring. Depending on the vehicle model or design requirements, it can be a single spring steel sheet or composed of multiple spring steel sheets stacked one on top of the other. In other embodiments of this application, composite spring sheets can also be used instead. In this application, when composed of multiple spring steel sheets, the width of each spring steel sheet should be equal. Specifically, when stacked one on top of the other, the width of each spring steel sheet should be equal at all locations. The thickness of each spring steel sheet can be the same or different depending on the design requirements. The length of each spring steel sheet (along the length of the vehicle) can be equal or unequal. In this application, the cross-sectional area of ​​each spring steel sheet at different locations along the length is equal or unequal. A mounting hole 22 is provided near each end of the auxiliary spring for mounting an adjustment assembly. A central hole 24 is provided at the center of the auxiliary spring for receiving a central bolt 70. In this application, the central hole 24 of the auxiliary spring is located at the center of the length to increase support under load.

[0038] The first pad 30 and the second pad 50 in the present application are usually equal to the width of the spring steel sheet of the main spring. The thickness of the pad can be adjusted as needed to adjust the initial distance between the two ends of the main spring, the auxiliary spring and the auxiliary leaf spring.

[0039] In the present application, the auxiliary leaf spring 40 may be a single spring steel sheet or may be composed of multiple spring steel sheets stacked one above the other, depending on the design or vehicle model. In other embodiments of the present application, a composite spring sheet may also be used instead. In the present application, if the auxiliary leaf spring 40 is composed of multiple spring steel sheets, the width of each spring steel sheet should be equal. Specifically, when the spring steel sheets are stacked one above the other, the width at each position should be equal. The thickness of each spring steel sheet can be the same or different depending on the design requirements, and the length of each spring steel sheet (along the length of the vehicle) can be equal or unequal. In the present application, the cross-sectional area of ​​each spring steel sheet at different positions along the length direction is equal or unequal.

[0040] In this application, the adjustment assembly 60 is composed of an adjustment pad assembly 80, a screw assembly 90 and a nut 62. The adjustment pad assembly 80 is composed of an adjustment pad 82 and an external hexagonal boss 84 arranged below the adjustment pad 82. A center threaded hole 86 is provided on the external hexagonal boss 84, and the center threaded hole 86 is threadedly matched with the threaded rod 92 of the screw assembly 90.

[0041] The screw assembly 90 includes a threaded rod 92, an external hexagonal support plate 94, and a circular tube portion 96. The external hexagonal support plate has a threaded hole in its center, and the inner side of the circular tube portion has an internal thread. One end of the circular tube portion is fixedly connected to the external hexagonal support plate. The external hexagonal support plate and the circular tube portion are threadedly connected to the threaded rod, and the circular tube portion cooperates with the mounting holes on the auxiliary spring. The external hexagonal support plate contacts the auxiliary spring. During installation, the circular tube portion of the screw assembly is inserted into the mounting holes at both ends of the auxiliary spring, and then the threaded rod is screwed into the external hexagonal support plate and the circular tube portion. The two ends of the threaded rod are then screwed into nuts to install the screw assembly on the auxiliary spring. The external hexagonal bosses of the two adjustment pad assemblies are then screwed onto the upper and lower ends of the threaded rod, and the specific position is adjusted using a wrench.

[0042] When the vehicle is unloaded, the leaf spring stiffness needs to be reduced. By rotating the external hexagonal boss, the adjusting washer assembly is rotated and screwed into the screw assembly. This increases the contact distance between the main spring, auxiliary spring, and auxiliary leaf spring. This results in delayed or no contact between the main and auxiliary springs during suspension movement, and no contact between the auxiliary and auxiliary leaf springs. In this case, the main spring is primarily responsible, resulting in lower stiffness and improved comfort. When the vehicle is fully loaded, the adjusting washer assembly is rotated by rotating the external hexagonal boss, partially withdrawing the adjusting washer assembly from the screw assembly. This allows the main and auxiliary springs, and the auxiliary and auxiliary leaf springs, to contact earlier during suspension movement. Both the auxiliary and auxiliary leaf springs now contribute to the operation, increasing leaf spring stiffness and load-bearing capacity. When overloaded, the adjusting washer assembly is rotated by rotating the external hexagonal boss, further withdrawing the adjusting washer assembly from the screw assembly. This allows the main and auxiliary springs to contact earlier or more frequently, and the auxiliary and auxiliary leaf springs to contact earlier. Because the auxiliary spring and auxiliary leaf spring participate in work earlier, the stiffness of the leaf spring is significantly improved, and the load-bearing capacity is significantly improved.

[0043] In this application, a motor can be connected to the adjustment pad assembly, which is driven by the motor to rotate the adjustment pad assembly. The adjustment pad assembly can be screwed into the vehicle to set the depth to high, standard, or low. High, medium, and low gears are arranged in the vehicle, corresponding to overload, full load, and no load, respectively. The customer adjusts the gear to the actual load situation. The switch transmits a signal to the ECU, which controls the motor to rotate the adjustment pad assembly to the corresponding position.

[0044] Although the present invention has been described herein with reference to illustrative embodiments of the present invention, it will be appreciated that those skilled in the art may devise numerous other modifications and implementations that fall within the scope and spirit of the principles disclosed herein. More specifically, within the scope disclosed herein, various variations and improvements may be made to the components and / or layout of the subject combination layout. In addition to variations and improvements made to the components and / or layout, other uses will be apparent to those skilled in the art.

Claims

1. A leaf spring assembly with adjustable stiffness, characterized in that: It includes a main spring, a secondary spring, an auxiliary leaf spring, a first pad, a second pad, an adjustment assembly and a center bolt; The main spring, the first pad, the auxiliary spring, the second pad, and the auxiliary leaf spring are arranged in sequence from top to bottom and fixed by a central bolt. Adjustment components are respectively provided at both ends of the auxiliary spring.

2. The stiffness-adjustable leaf spring assembly according to claim 1, characterized in that: The main spring, the auxiliary spring and the auxiliary leaf spring are each composed of a single or multiple spring steel sheets, and the widths of the spring steel sheets of the main spring, the auxiliary spring and the auxiliary leaf spring are all equal.

3. The stiffness-adjustable leaf spring assembly according to claim 2, characterized in that: The cross section of each spring steel sheet in the length direction is a uniform cross section and / or a variable cross section, the widths of the spring steel sheets are equal, the thicknesses of the spring steel sheets are the same or different, and the lengths of the spring steel sheets are equal or different.

4. The stiffness-adjustable leaf spring assembly according to claim 2, characterized in that: The two ends of the first spring steel sheet of the main spring are respectively provided with a front coil ear and a rear coil ear for installing a spring pin.

5. The stiffness-adjustable leaf spring assembly according to claim 1, characterized in that: The length from the central bolt hole to the front end of each spring steel sheet of the main spring is smaller than the length from the central bolt hole to the rear end, and the curvature from the central bolt hole to the front end is smaller than the curvature from the central bolt hole to the rear end.

6. The stiffness-adjustable leaf spring assembly according to claim 1, characterized in that: Noise reduction pads are provided at the contact positions of each spring steel sheet of the main spring.

7. The stiffness-adjustable leaf spring assembly according to claim 2, characterized in that: A mounting hole is provided near both ends of the uppermost spring steel plate of the auxiliary spring for mounting the adjustment assembly.

8. The stiffness-adjustable leaf spring assembly according to claim 7, characterized in that: The adjustment assembly is composed of an adjustment pad assembly, a screw assembly and a nut. The adjustment pad assembly is composed of an adjustment pad and an external hexagonal boss arranged below the adjustment pad. The external hexagonal boss is provided with a central threaded hole, and the central threaded hole is threadedly matched with the threaded rod of the screw assembly. The screw assembly includes a threaded rod, an external hexagonal support plate and a circular tube portion. A threaded hole is provided in the center of the external hexagonal support plate, and an internal thread is provided on the inner side surface of the circular tube portion. One end of the circular tube portion is fixedly connected to the external hexagonal support plate. The external hexagonal support plate and the circular tube portion are threadedly connected to the threaded rod, and the circular tube portion cooperates with the mounting hole on the auxiliary spring.

9. The stiffness-adjustable leaf spring assembly according to claim 8, characterized in that: A nut is provided at each end of the threaded rod.

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