DESC:SUSPENSION COIL SPRING FOR A SUSPENSION SYSTEM

FIELD OF THE INVENTION
The present invention in general relates to a mechanical suspension for automotive, and more particularly to a suspension coil spring for a suspension system.
BACKGROUND
Vehicles encounter fluctuating loads and forces when traveling on uneven roads, affecting their smooth movement and causing discomfort for passengers due to jerks. The suspension system plays a crucial role in the vehicles in absorbing these forces and ensuring a comfortable ride. The suspension systems can be broadly classified into independent suspension systems and dependent suspension systems. In the independent suspension systems, each wheel includes own suspension system, ensuring that jerks experienced by one wheel do not directly affect the other wheel. However, in the dependent suspension systems, the jerks experienced by one wheel, transmit forces to another wheel, which can reduce ride comfort.
FIG. 1A illustrates a Macpherson Strut suspension system 100 according to prior art. The Macpherson Strut suspension system 100 is a widely used independent suspension system. The Macpherson Strut suspension system 100 includes a coil spring 102, a strut with damper 104, a knuckle 106, and an anti-roll bar 108. The Macpherson Strut suspension system 100 is employed in front axles of small and medium-sized front wheel drive vehicle. The Macpherson strut suspension system 100 is cheaper and lighter compared to double wishbone suspension systems. In the Macpherson strut suspension system 100, an upper control arm found in the double wishbone suspension systems is replaced by a strut rigidly connected to the wheel spindle. While the Macpherson strut suspension system 100 provides advantages in costs and space, it limits in handing performance due to reduced control over roll, pitch, and wheel angles.
Major drawback in the Macpherson strut suspension system 100 is a presence of lateral forces acting on the Macpherson strut suspension system 100, which leads to damper friction and decrease the ride performance on the vehicle. These lateral forces create moments (torque) in the seat during cornering, which may lead to degrade suspension performance, reduce passenger comfort, and cause premature spring failure. Conventional springs may be capable of absorbing vertical load, but the conventional springs do not mitigate the effects of lateral forces fully. Due to the lateral forces issue, the Macpherson strut suspension system 100 cannot have comfort zone because of interference issue between the strut and knuckle 106 or the wheel assembly.
The MacPherson strut suspension system 100 experiences several drawbacks when subjected to lateral forces, particularly during cornering. One significant issue is that conventional coil springs lack the ability to absorb lateral forces. As a result, side forces are developed on the strut, leading to undesired dry friction between the damper piston and cylinder, as well as between the damper piston rod and cylinder bearing. This friction causes a stick-slip action, which impacts ride comfort by creating jerky movements and vibrations. This friction also results in undue damage to the piston and piston rod seals, while the spring lose effectiveness due to buckling.
The strut with damper 104 is mounted on the lower control arm to absorb both sprung and unsprung loads acting on the MacPherson strut suspension system 100. However, in addition to these vertical loads, the strut with damper 104 absorbs significant lateral forces with offset and tilt angle spring seat extreme to meet the load axis point exerted from the tire contact and offset, and the top seat and the bottom seat.
FIG. 1B illustrates a seat offset effect on the strut with damper 104 of FIG. 1 according to prior art. The offset and tilt angle at a lower seat of the strut with damper 104, absorb small amount of restriction on lateral forces. However, increasing the tilt and offset beyond limits can lead to undesirable effects on the spring's behavior in the MacPherson strut suspension system 100. Research by Thomas Wunsche and Muhr highlights the challenges associated with shifting the spring seat in the strut assembly of the MacPherson strut suspension system 100.
Existing solution of SAE Paper No. 940862 by Thomas and Karl-Heinz Muhr explains the side load spring with an S-shape, which reduces the risk of coil clash and improves ride comfort by mitigating damper friction. However, the focus is mainly on the performance characteristics of the side load spring, with little emphasis on the detailed design considerations. Another existing solution of SAE Paper No. 960730 by Satoshi and Syuji provides the effects of tilting angles in spring seats and open-end coils. This solution demonstrates reducing the side forces by tilting the upper seat, but detailed information on design considerations for side force springs are not provided.
Another existing solution of SAE Paper No. 2000-01-0101 by Takashi Gotoh and Toshiyuki discloses a new spring design with a curved coil axis that improves reaction force performance. However, the spring design is not clearly defined, and the side load spring design is only evaluated in a test environment. In yet another existing solution of SAE Paper No. 2006-01-1375 by Shinichi Nishizawa and Winda Ruiz utilizes vector analysis to determine the ideal force line position. This solution concludes that when the force line passes through the upper mount on the plane formed by the kingpin and damper axis, self-steering issues could be minimized, which is not clearly defined in addressing the lateral forces.
Spring structure plays a crucial role in ensuring proper load axis point in the vehicle suspension system. Conventional coil springs face limitations that may be identified through design analysis and simulation methods. These conventional coil springs are designed to handle loads in Z- direction i.e. vertical axis, while the effects of lateral forces in Y and Z directions i.e. horizontal and vertical axes, are not considered.
FIG. 1C illustrates a suspension coil spring 110 according to prior art. The suspension coil spring 110 i.e. a helical spring, is configured to direct the force line position in a desired direction relative to the central axis of the suspension coil spring110. In the suspension system, the suspension coil spring 110 may carry load up to 80% as an elastic component, to compress under load and return to its original shape once the load is removed. The suspension coil spring 110 is configured to control the load axis to minimize the bending moment. Parameters including stiffness, number of coils, spring profile, and outer diameter of the suspension coil spring 110 enables controlling of the load axis. In some existing solutions, a side coil spring assembly can be integrated with a shock absorber to control the load axis.
FIG. 1D illustrates a normal suspension coil spring and a buckled suspension coil spring of FIG. 1C according to prior art. Under normal load conditions, the suspension coil spring 110 is configured to absorb the vertical forces acting on the suspension system. During cornering or under lateral forces, the suspension coil spring 110 tend to buckle, compromising its structural integrity. MacPherson strut used in front suspension faces premature failure in the suspension coil spring as the spring axis is unable to meet the load axis (i.e. a piercing point/Kingpin axis).
However, there is still a need for a comprehensive approach that eliminates the undesired effects of the lateral forces as well as to improve the ride and handling performance of the vehicle.

SUMMARY OF INVENTION
This section is provided to introduce certain objects and aspects of the present disclosure in a simplified form that are further described below in the detailed description. This summary is not intended to identify the key features or the scope of the claimed subject matter.
It is an object of the present invention to eliminate the undesired effects of lateral forces on the suspension strut and wheels of a vehicle.
It is another object of the invention to enhance ride comfort and handling performance of the vehicle.
It is yet another object of the invention to design a U-axis side load spring that aligns with the vehicle’s load axis point.
It is yet another object of the invention to design a U-axis spring using Finite Element (FE) analysis and compare the results obtained on a physical U-axis spring model with conventional side load springs.
It is yet another object of the invention to define the mathematical 3D coordinates of the spring, including axis angle/amount, seat angle, and bend portion defining the pitch helix angle, using conventional spring parameter.
It is yet another object of the invention to calculate the piercing point/hard point considering the vehicle parameter and U-axis spring structure.
In view of foregoing, an embodiment herein provides a suspension coil spring for a suspension system. The suspension coil spring includes a U-axis spring structure that is configured to control load axis with respect to a strut axis. The U-axis spring structure includes one or more turns including an upper coil, a bottom coil, and a middle coil. The upper coil is mounted to an upper strut seat. The bottom coil is mounted to a lower strut seat. The middle coil is configured to act as load absorbing unit, and configured to minimize the buckling behaviour under lateral forces effect. The U-axis spring structure is configured to avoid the lateral forces effect using U-axis shape, thereby reducing frictional moments.
In some embodiments, the U-axis spring structure is adjustable to accommodate different load axis requirements with higher piercing point.
In some embodiments, the U-axis spring structure is configured to optimize alignment with the load axis under lateral and vertical forces.
In some embodiments, the U-axis spring structure includes an upper and lower end turn that controls the load axis within the suspension coil spring, thereby improving end turn contact load distribution.
In some embodiments, the U-axis spring structure includes an end turn angle for the upper coil and the bottom coil, which is configured to align based on a seat tilt angle and the U-axis.
In some embodiments, the end turn angle optimizes with the U-axis spring structure for load distribution in vertical and lateral forces, managing interference and contact distribution.
In some embodiments, the U-axis spring structure including an optimal number of turns, pitches, and end turns are determined with Euler equations and Trigonometric functions.
In some embodiments, the U-axis spring structure has a piercing point that is dynamically calculated by analysing real-time vehicle load and motion data to continuously optimize the U-axis spring structure.
In some embodiments, the U-axis spring structure is configured to enhance effectiveness with a design of the upper end turn, close with X.3 turns. X is a number of turns calculated by analyzing load and working height specifications.
In an aspect, an embodiment herein provides a vehicle suspension system. The vehicle suspension system is configured to control load axis with respect to a strut axis. The suspension coil spring includes a U-axis spring structure that is configured to distribute lateral forces along a U-axis to reduce frictional moments. The U-axis spring structure includes an upper coil, a bottom coil, a middle coil, an upper and lower end turn, and an end turn angle. The upper coil is connected to an upper strut seat. The bottom coil is connected to a lower strut seat. The middle coil acts as load absorbing unit, and configured to minimize buckling behaviour under lateral forces effect. The upper and lower end turn is configured to control load axis distribution within the suspension coil spring, thereby improving end turn contact load distribution. The end turn angle for the upper coil and bottom coil, aligned with a seat tilt angle and the U-axis to optimize load alignment and distribution. The U-axis spring structure is dynamically adjustable to accommodate varying load axis requirements with respect to vehicle co-ordinate system, and optimize alignment under lateral and vertical forces.
In some embodiments, the U-axis spring structure has a piercing point that is dynamically calculated by analysing real-time vehicle load and motion data to continuously optimize the U-axis spring structure.
The U-axis spring structure includes an ability to meet higher piercing points through the U-axis spring design. The U-axis spring structure provides an end turn tilt angle design and simplifies the understanding of axis shifts with respect to load axis requirements. The U-axis spring structure leads to improved handling and comfort to the vehicle. Spring of the U-axis spring structure is developed using FE analysis and incorporates mathematical 3D coordinates for spring parameters like axis angle, seat angle, and bend portion defining the pitch helix angle. The U-axis spring structure is based on the suspension hard points and vehicle integration, with both ends acting as active turns, while the middle active turn height is precisely determined based on seat angle, offset distance and hard points.
The compression and extraction functions of the U-axis spring structure are well-suited for vehicle operations without deviating essential functional parameters such as load and stiffness. Each coil turn in the U-axis spring structure is precisely controlled by adjusting an offset axis and a profile of the U-axis spring structure. Space utilization within the strut assembly is optimized, as the offset distance can be adjusted for subsequent turns in the U-axis spring structure. The pitch helix angle can be regulated for each turn, while the top and bottom end turn tilt angles are designed in alignment with the seat tilt angle and the U-axis area (0 to 1 turn) to ensure high effectiveness.
The U-axis spring structure with an end turn angle tilt that aligns with the load axis, provide an integration design for the vehicles. The U-axis spring structure leverages the interference gap within the knuckle and wheel assembly structure, eliminating undesired force effects, to meet the load axis point in the vehicle. The U-axis spring structure addresses key challenges in modern suspension systems by providing improved control over lateral forces and enhancing overall vehicle ride performance.

BRIEF DESCRIPTION OF DRAWINGS
The accompanying drawings, which are incorporated herein, and constitute a part of this invention, illustrate exemplary embodiments of the disclosed methods and systems which like reference numerals refer to the same parts throughout the different drawings. Components in the drawings are not necessarily to scale, emphasis instead being placed upon clearly illustrating the principles of the present invention.
Although exemplary connections between sub-components have been shown in the accompanying drawings, it will be appreciated by those skilled in the art, that other connections may also be possible, without departing from the scope of the invention. All sub-components within a component may be interconnected unless otherwise indicated.
FIG. 1A illustrates a Macpherson Strut suspension system according to prior art;
FIG. 1B illustrates a seat offset effect on a strut with damper of FIG. 1 according to prior art;
FIG. 1C illustrates a suspension coil spring according to prior art;
FIG. 1D illustrates a normal suspension coil spring and a buckled suspension coil spring of FIG. 1C according to prior art;
FIG. 2 illustrates a block diagram of a suspension coil spring for a suspension system according to some embodiments herein;
FIG. 3A is a flowchart of a method for designing the suspension coil spring of FIG. 2 according to some embodiments herein;
FIG. 3B illustrates a vehicle coordinate system for designing and shaping a U-axis spring structure according to some embodiments herein;
FIG. 3C illustrates an exemplary view of hard points of axis according to some embodiments herein;
FIG. 3D illustrates an exemplary view of a strut and force line acting on the suspension system according to some embodiments herein;
FIGS. 4A-4G illustrate exemplary views for defining the U-axis spring structure to meet the load axis requirements according to some embodiments herein;
FIG. 5A illustrates an exemplary view of a Finite Element (FE) mesh of the U-axis spring structure for simulation and validation to define load axis according to some embodiments herein;
FIG. 5B illustrates an exemplary view of an upper end turn position of the U-axis spring structure according to some embodiments herein;
FIG. 5C illustrates an exemplary graphical representation of end turn effectiveness results of FIG. 5B according to some embodiments herein;
FIG. 5D illustrates an exemplary view of the seat and the end turn contact region of the U-axis spring structure with a uniform contact area between seat and spring at vehicle working condition according to some embodiments herein; and
FIG. 5E illustrates an exemplary view of an actual model of the U-axis spring structure according to some embodiments herein.
The foregoing shall be more apparent from the following more detailed description of the invention.

DETAILED DESCRIPTION
The following presents a detailed description of various embodiments of the present subject matter with reference to the accompanying drawings.
The embodiments of the present disclosure are described in detail with reference to the accompanying drawings. The invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this invention will be thorough and complete, and will fully convey its scope to those skilled in the art. The terminology used in the detailed description of the exemplary embodiments illustrated in the accompanying drawings is not intended to be limiting. In the drawings, like numbers refer to like elements.
The specification may refer to “an”, “one”, “different” or “some” embodiment(s) in several locations. This does not necessarily imply that each such reference is to the same embodiment(s), or that the feature only applies to a single embodiment. Single features of different embodiments may also be combined to provide other embodiments.
As used herein, the singular forms “a”, “an” and “the” are intended to include the plural forms as well, unless expressly stated otherwise. It will be further understood that the terms “includes”, “comprises”, “including” and/or “comprising” when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being “attached” or “connected” or “coupled” or “mounted” to another element, it can be directly attached or connected or coupled to the other element or intervening elements may be present. As used herein, the term “and/or” includes any and all combinations and arrangements of one or more of the associated listed items.
Unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skills in the art to which this invention pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
In the following description, for the purposes of explanation, numerous specific details have been set forth in order to provide a description of the invention. It will be apparent, however, that the invention may be practiced without these specific details and features.
The figures accompanying the specification depict a simplified structure only showing some elements and functional entities, all being logical units whose implementation may differ from what is shown.
The present disclosure relates to a vehicle suspension system that provides a smooth ride over rough terrain while ensuring continuous contact between the wheels and the ground, minimizing vehicle roll. The shape of the present U-axis spring structure allows a shift in the load axis based on user requirements and terrain conditions. The U-axis spring structure includes an end turn angle tilt on both sides to optimize the load axis point.
FIG. 2 illustrates a block diagram of a suspension coil spring 200 for a suspension system 202 according to some embodiments herein. The suspension coil spring 200 includes a U-axis spring structure 204. The U-axis spring structure 204 is configured to control load axis with respect to a strut axis. The U-axis spring structure 204 includes one or more turns including an upper coil 206, a middle coil 208, and a bottom coil 210. The upper coil 206 is mounted on an upper strut seat. The bottom coil 210 is mounted to a lower strut seat. The middle coil 208 is configured to act as load absorbing unit, and configured to minimize the buckling behaviour under lateral forces effect. The U-axis spring structure 204 is configured to avoid the lateral forces effect using U-axis shape, thereby reducing frictional moments. In some embodiments, the U-axis spring structure 204 has a piercing point that is dynamically calculated by analyzing real-time vehicle load and motion data to continuously optimize the U-axis spring structure 204. In some embodiments, the U-axis spring structure 204 is adjustable to accommodate different load axis requirements with higher piercing point. The U-axis spring structure 204 may optimize alignment with the load axis under lateral and vertical forces.
In some embodiments, the U-axis spring structure 204 includes an upper and lower end turn that controls the load axis within the suspension coil spring 200, thereby improving end turn contact load distribution. In some embodiments, the U-axis spring structure 204 includes an end turn angle for the upper coil 206 and the bottom coil 210, which is configured to align based on a seat tilt angle and the U-axis. The end turn angle may optimize with the U-axis spring structure 204 for load distribution in vertical and lateral forces, managing interference and contact distribution.
In some embodiments, the U-axis spring structure 204 includes an optimal number of turns, pitches, and end turns are determined with Euler equations and Trigonometric functions. The U-axis spring structure 204 may be configured to enhance effectiveness with a design of the upper end turn, close with X.3 turns, where X is a number of turns calculated by analysing load and working height specifications.
In some embodiments, a vehicle suspension system is provided. The vehicle suspension system includes the suspension coil spring 200 that is configured to control load axis with respect to the strut axis. The suspension coil spring 200 includes the U-axis spring structure 204. The U-axis spring structure 204 includes the upper coil 206, the middle coil 208, the bottom coil 210, the upper and lower end turn, and the end turn angle. The upper coil 206 is connected to the upper strut seat, the bottom coil 210 is connected to the lower strut seat, and the middle coil 208 acts as load absorbing unit and configured to minimize buckling behaviour under later forces effect. The upper and lower end turn configured to control load axis distribution within the suspension coil spring 200, thereby improving end turn contact load distribution. The end turn angle for the upper coil 206 and the bottom coil 210 are aligned with the seat tilt angle and the U-axis to optimize load alignment and distribution. The U-axis spring structure 204 is dynamically adjustable to accommodate varying load axis requirements with respect to vehicle co-ordinate system, and optimize alignment under lateral and vertical forces. In some embodiments, the U-axis spring structure 204 has a piercing point that is dynamically calculated by analyzing real-time vehicle load and motion data to continuously optimize the U-axis spring structure 204. In some embodiments, the U-axis spring structure 204 includes axis angle, turn position, bend turn height, and seat to spring tilting angle, based on the load axis requirement and interference point of view.
FIG. 3A is a flowchart of a method for designing the suspension coil spring 200 of FIG. 2 according to some embodiments herein. At a step 302, the method includes studying and analyzing suspension system assembly hard points. In some embodiments, the load axis requirement can be defined for designing the U-axis spring structure 204. At a step 304, the method includes designing and shaping generation of the U-axis spring structure 204. In some embodiments, the U-axis spring structure 204 can be designed meeting requirements including rate, load, and dimensional parameter. The method may include inputting angles, turn position and height of the U-axis spring structure 204. At a step 306, the method includes analyzing the design and shape of the U-axis spring structure 204 using a software approach. The method includes evaluating the axis direction to meet the load axis requirement, and determining whether the suspension system assembly hard points are satisfied or not.
At a step 308, the method includes redesigning the U-axis spring structure 204 when the designed and shaped U-axis spring structure does not meet requirements of the vehicle assembly. In some embodiments, the method includes changing the angle and the position of the U-axis spring structure 204 and moves to the step 304.
At a step 310, the method includes validating the designed and shaped U-axis spring structure on an actual sample when the designed and shaped U-axis spring structure meet requirements of the vehicle assembly. In some embodiments, the performance of the U-axis spring structure 204 can be validated using Finite Element Analysis (FEA) and actual sample.
FIG. 3B illustrates a vehicle coordinate system for designing and shaping the U-axis spring structure 204 according to some embodiments herein. The U-axis spring structure 204 can be designed and shaped by analyzing the vehicle parameters, the vehicle coordinate system, and requirements of the load axis.
FIG. 3C illustrates an exemplary view of hard points of axis according to some embodiments herein. Below mentioned table shows the hard points of axis:

Hard Points in mm Spring axis hard points Load hard points
Upper Seat XU ± Tolerance SXU KXU
YU ± Tolerance SYU KYU
Lower Seat XL ± Tolerance SXL KXL
YL ± Tolerance SYL KYL

The spring axis hard points to may meet the load hard points requirement, to eliminate 0the side force effect on the U-axis spring structure 204. In some embodiments, the upper seat is a top seat, and the lower seat is a bottom seat.
FIG. 3D illustrates an exemplary view of a strut line 312 and a force line 314 acting on the suspension system 202 according to some embodiments herein. The force line 314 may be defined relative to the top seat and the bottom seat i.e. seat angle with offset 316, using the hard points of axis, and piercing points along the force line 314 may be determined. In some embodiments, parameters including direction, seat angle, offset distance, and piercing point values provide the foundational data for designing the U-axis spring structure 204.
FIGS. 4A-4G illustrate exemplary views for defining the U-axis spring structure 204 to meet the load axis requirements according to some embodiments herein. FIG. 4A depicts an exemplary view of determining an angle between the strut axis and the load axis. The exemplary view includes a tire contact path 402, a load axis path 404, and a strut axis 406. Spring 3D coordinates equation is as follows,

X=r*sin?, Y= - r*cos?, Z=Height … Equation-1

In some embodiments, CAD model of the U-axis spring structure 204 can be developed by deriving the U-axis spring transformation matrix and Euler equation. The force line is extracted between the tire contact path 402 and steering hardpoints, to measure the angle between the struct axis and the load axis. The bottom end of the spring may be relocated or assembled to the seat location using a 3D rotation along the coordinate axis.
Equation-1 is for the 3D coordinate system, assuming S = (X, Y, Z) and rotating the point S about Z-axis, which defines the pitch direction. The Z-coordinate of S remains unchanged, while the X and Y coordinates rotate according to the defined angle ?, similar to 2D rotation. After rotating S by the angle ?, the new coordinates are given by S’= (X’, Y’, Z’).

X’ = Xcos ? - Ysin ? …. Equation-2
Y’ = Xsin ? - Ycos ? …. Equation-3
Z’ = Z …. Equation-4

The observed equations 2, 3, and 4 are written in matrix form:

[¦(X^'@Y^'@Z')]=[¦(cos?&-sin?&0@sin?&cos?&0@0&0&1)]*[¦(X@Y@Z)] … Equation 5

FIG. 4B depicts an exemplary view of normal coordinates and rotation coordinates of the U-axis spring structure 204 defined by Equation 5 to assemble in seat starting location. The U-axis spring structure 204 including an upper spring portion that is connected to an upper mounting area, and a lower spring portion is connected to a bottom mounting area. In some embodiments, the upper spring portion can be mounted to the upper strut seat, and the lower spring portion can be mounted to the lower strut seat. The piercing point is configured to shift compared to the upper mounting area, when the difference between the load axis and the strut axis angle is observed on movement of the load towards the tire. The U-axis spring structure 204 may be designed using Euler's equation and hyperbolic trigonometric functions to model the side load spring. The shape of the U-axis spring structure 204 is primarily determined by the load axis angle requirements relative to the strut axis. In some embodiments, the seat angle and load axis angle enable determining an offset distance of the U-axis. The U-axis spring structure 204 may consists of number of turns, end turn profile, and pitch height.
FIG. 4C depicts an exemplary view of U-axis spring structure 204. Each active turn stiffness and load functionality enables the U-axis spring structure 204 to meet the load axis requirements. The U-axis spring structure 204 includes a spring axis 408, and a U-axis 410. Based on the load axis angle difference, the U-axis spring structure 204 is divided into three portions including the upper coil 206, the middle coil 208, and the bottom coil 210 including pitch distance and turn distance in each of the portions. The bottom coil 210 and the upper coil 206 contribute to aligning with the load axis, while the middle coil 208, forming the U-axis region, thereby preventing spring buckling during operation. The offset distance of the U-axis may be controlled by adjusting the coil turns and spring height, using trigonometric calculations.
In some embodiments, the load axis requirement can be in higher side in a strut assembly with knuckle in the suspension system, which enables the end turn to utilize more effectively to meet the load axis requirement. In a coil spring of the U-axis spring structure 204, both upper and bottom profiles from 0 to 1 end turn, function as load transfer points for active turn performance. In some embodiments, end turn pitch distribution, relative to the pitch of the active turns, ensures alignment with the higher load axis.
FIG. 4D depicts an exemplary view of seat angle from strut axis. The exemplary view includes a strut 412, a seat 414, and a seat angle “?t” 416. The seat angle 416 is defined as an angle between a line parallel to seat surface and a line perpendicular to strut axis.
FIG. 4E depicts an exemplary view of effective regions of end turn profile of the U-axis spring structure 204. The U-axis spring structure 204 can be enabled to shift up to the angles ?u and ?l on the end profile angle, to define U-axis line. In some embodiments, a region above the seat angle “?t” 416 is a highly effective area extending up to ?u and ?l on the end profile angle. The U-axis design with the end profile angle can be maintained according to the angles ?tl and ?tu, and the end turn angle remains within the U-axis and spring axis regions for achieving a higher piercing point based on the spring and load axis requirements.
Bottom end turn angle profile = “?l - ?tl”
Upper end turn angle profile = “?u - ?tu”
FIG. 4F depicts a graphical representation of end turn profile variation. The graphical representation includes number of turns in an X-axis, and a profile distance in mm in a Y-axis. The graphical representation defines a base profile, and a U-axis design and end turn angle profile. The graphical representation shows a profile design at end turn comparing with base profile dimension.
FIG. 4G depicts an exemplary view of the U-axis spring structure 204 with the U-axis and the end profile angle. The U-axis spring structure 204 includes the upper coil 206, the bottom coil 210 and a U-axis region 418.
FIG. 5A illustrates an exemplary view of a Finite Element (FE) mesh of the U-axis spring structure 204 for simulation and validation to define load axis according to some embodiments herein. In some embodiments, the U-axis spring structure 204 can be designed and analysed using FE analysis with Abaqus software, enabling better contact behavior. The U-axis spring structure 204 may be assembled with the upper seat and the lower seat. FE model of the U-axis spring structure 204 can be constructed based on vehicle hard points and the strut axis. During the FE analysis with Abaqus software on the FE model, the focus is on component of the U-axis spring structure 204, while the upper seat and the lower seat can be modelled as rigid bodies and the U-axis spring structure 204 as a deformable body. In some embodiments, a high-quality mesh and required boundary conditions can be applied to simulate vehicle displacement behavior, ensuring accuracy.
Post-processing in the Abaqus software, reaction forces and moments acting on the upper seat and the lower seat may be extracted and enables calculation of the load axis and piercing point values. In some embodiments, the bottom seat can be considered as a starting coil turn and the upper seat as an end turn to evaluate the effectiveness of the U-axis spring structure 204. In some embodiments, the stiffness, wire diameter, load, and height may be constant, while the number of coil turns for the U-axis spring structure 204 varies, and an amount of U-axis shift remains fixed. The same meshing and modelling procedures may be followed for different end turn designs in the FE model.
FIG. 5B illustrates an exemplary view of an upper end turn position of the U-axis spring structure 204 according to some embodiments herein. Turn position of the U-axis spring structure 204 includes 0 turn, 0.1 turn, 0.2 turn, 0.3 turn, 0.4 turn, 0.5 turn, 0.6 turn, 0.7 turn, 0.8 turn, and 0.9 turn. Each upper seat of each of the FE model of the U-axis spring structure 204 subjects to the FE simulation, where the force and moment may be measured under installed conditions. In some embodiments, the load axis and the piercing point can be calculated based on these results.
FIG. 5C illustrates an exemplary graphical representation of end turn effectiveness results of FIG. 5B according to some embodiments herein. The graphical representation includes a number of turns in an X-axis and a piercing point value in mm in a Y-axis. The graphical representation shows that the piercing point for the U-axis spring structure 204, the upper seat end turn 0.2 to 0.7 turns provide more effectiveness. The U-axis spring structure 204 offers enhanced comfort due to optimized turns, height, and profile. And, the graphical representation indicates that an end turn of 0.3 is more effective.

S. No. Parameter Specification
1 Wire Diameter in mm 12.5
2 Mean Coil diameter in mm 142.0
3 Install/Design Height in mm 265
Load in N 2584
4 Stiffness in N/mm 20
5 Number of turns 5.3

TABLE 1

For achieving a higher piercing point above YL = above 50 mm, the specifications are provided in above mentioned table. To meet this higher point value, a combination of U-axis and the end profile angle is applied, incorporating a greater axis shift. In some embodiments, the designed U-axis spring structure 204 follows the FE analysis to extract forces and moments at the installed position. The U-axis spring structure 204 ensures uniform contact between both end turns and the seat throughout the working conditions of the U-axis spring structure 204, thereby preventing buckling and ensuring equal load transfer to the active coils.
FIG. 5D illustrates an exemplary view of the seat and the end turn contact region of the U-axis spring structure 204 with a uniform contact area between seat and spring 502 at vehicle working condition according to some embodiments herein. The seat and end turn contact region functions as a load transferring system on active coils of the U-axis spring structure 204. The uniform contact area between seat and spring 502 is a contact region between the end turn and strut seat.
FIG. 5E illustrates an exemplary view of an actual model of the U-axis spring structure 204 according to some embodiments herein. The specifications outlined in Table 1 can be used, and the cold coiling process can be followed to develop the U-axis spring structure 204. The actual model of the U-axis spring structure 204 may be subjected to piercing point measurements. In some embodiments, a side load measurement testing machine can be used on the actual model to measure the force and moment at the installed height, determining the piercing point value. Comparison results of the actual model and the FE model of the U-axis spring structure 204 are mentioned in the below mentioned table:

Conventional /Normal Helix Spring
Piercing Points @ Install condition in mm Strut Seating Direction FE-Model Actual sample
Upper Seat XU -3.8 -2.5
YU 4.2 3.5
Lower Seat XL 1.8 2.3
YL 9.6 11.2

TABLE 2

For example, the FE analysis can be conducted in the FE model of the U-axis spring structure 204 to determine the reaction force in all directions. The seat and dimension are considered for the FE analysis as per strut condition, and from the FE analysis, the reaction force and moment can be obtained. Based on the reaction force and moment, the hard point axis is calculated at a design condition. Observed values of the FE model and actual sample of the U-axis spring structure 204 are mentioned in the below table:

U-axis Spring
Piercing Points @ Install condition in mm Strut Seating Direction FE-Model Actual sample
Upper Seat XU 1.4 1.5
YU 3.7 2.2
Lower Seat XL 2.7 1.6
YL 54.4 51.3

TABLE 3

Based on the results of the Table 3, the FE model of the U-axis spring structure 204 and the actual model of the U-axis spring structure 204, provides a piercing point in a range of 45mm to 55mm. The actual sample may be manufactured considering the design parameter and load axis design of the U axis spring structure 204. In some embodiments, end turn position of the U-axis spring structure 204 can been tilted to meet the desired load axis. End turn position may be utilised as an active turn for certain height.
The foregoing description of the specific embodiments will so fully reveal the general nature of the embodiments herein that others can, by applying current knowledge, readily modify and/or adapt for various applications such specific embodiments without departing from the generic concept, and, therefore, such adaptations and modifications should and are intended to be comprehended within the meaning and range of equivalents of the disclosed embodiments. It is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation. Therefore, while the embodiments herein have been described in terms of preferred embodiments, those skilled in the art will recognize that the embodiments herein can be practiced with modification within the spirit and scope of the appended claims.

Dated this 12th day of November 2024
Sachin Manocha
IN/PA 3247
Of KRIA Law
Agent for the Applicant
,CLAIMS:CLAIMS
I/We claim:
1. A suspension coil spring (200) for a suspension system (202), comprising:
a U-axis spring structure (204) that is configured to control load axis with respect to a strut axis, wherein the U-axis spring structure (204) comprises a plurality of turns comprising:
an upper coil (206) that is mounted to an upper strut seat;
a bottom coil (210) that is mounted to a lower strut seat; and
a middle coil (208) that is configured to act as load absorbing unit, and configured to minimize the buckling behaviour under lateral forces effect;
wherein the U-axis spring structure (204) is configured to avoid the lateral forces effect using U-axis shape, thereby reducing frictional moments.

2. The suspension coil spring (200) as claimed in claim 1, wherein the U-axis spring structure (204) is adjustable to accommodate different load axis requirements with higher piercing point.

3. The suspension coil spring (200) as claimed in claim 1, wherein the U-axis spring structure (204) is configured to optimize alignment with the load axis under lateral and vertical forces.

4. The suspension coil spring (200) as claimed in claim 1, wherein the U-axis spring structure (204) comprises an upper and lower end turn that controls the load axis within the suspension coil spring (200), thereby improving end turn contact load distribution.

5. The suspension coil spring (200) as claimed in claim 1, wherein the U-axis spring structure (204) comprises an end turn angle for the upper coil (206) and the bottom coil (210), which is configured to align based on a seat tilt angle and the U-axis.
6. The suspension coil spring (200) as claimed in claim 5, wherein the end turn angle optimizes with the U-axis spring structure (204) for load distribution in vertical and lateral forces, managing interference and contact distribution.

7. The suspension coil spring (200) as claimed in claim 1, wherein the U-axis spring structure (204) comprising an optimal number of turns, pitches, and end turns are determined with Euler equations and Trigonometric functions.

8. The suspension coil spring (200) as claimed in claim 1, wherein the U-axis spring structure (204) has a piercing point that is dynamically calculated by analyzing real-time vehicle load and motion data to continuously optimize the U-axis spring structure (204).

9. The suspension coil spring (200) as claimed in claim 1, wherein the U-axis spring structure (204) is configured to enhance effectiveness with a design of the upper end turn, close with X.3 turns, wherein X is a number of turns calculated by analyzing load and working height specifications.

10. A vehicle suspension system, comprising:
a suspension coil spring (200) configured to control load axis with respect to a strut axis, the suspension coil spring (200) comprising:
a U-axis spring structure (204) configured to distribute lateral forces along a U-axis to reduce frictional moments, the U-axis spring structure (204) comprising:
an upper coil (206) connected to an upper strut seat;
a bottom coil (210) connected to a lower strut seat;
a middle coil (208) acting as load absorbing unit, configured to minimize buckling behaviour under lateral forces effect;
an upper and lower end turn configured to control load axis distribution within the suspension coil spring (200), thereby improving end turn contact load distribution; and
an end turn angle for the upper coil (206) and bottom coil (210), aligned with a seat tilt angle and the U-axis to optimize load alignment and distribution;
wherein the U-axis spring structure (204) is dynamically adjustable to accommodate varying load axis requirements with respect to vehicle co-ordinate system, and optimize alignment under lateral and vertical forces.

11. The vehicle suspension system as claimed in claim 10, wherein the U-axis spring structure (204) has a piercing point that is dynamically calculated by analyzing real-time vehicle load and motion data to continuously optimize the U-axis spring structure (204).