The present invention relates to a leaf spring structure designed as a single piece to be able to change the spring rate of leaf springs under load independently from the manufacturing material. The present invention particularly rate relates to an operating mechanism that is capable of increasing the spring rate as a result of the interaction between the short spring and the long spring after a certain vertical displacement while the short spring and the long spring, which are the two regions of the leaf spring, are operating together.
In the state of the art, the spring rate of the spring should increase as shown in
Leaf springs that are commonly used in the state of the art feature the form shown in
However, auxiliary layers used in leaf springs increase the weight of leaf springs, and correspondingly, they increase the overall weight of the vehicle, thereby increasing the carbon emission. In addition, leaf springs with multiple layers generate vibrations while driving and cause chassis fatigue. Furthermore, materials used during the assembly of the main layer and the auxiliary layer induce strength losses.
The preliminary search conducted in the state of the art has shown that the technical content of the patent application numbered TR2015/10669 mentions a spring shackle integrated into at least one of the ends of the leaf spring as shown in
The preliminary search conducted in the state of the art has shown that the technical content of the patent application numbered GB585984A mentions that the laminated leaf spring system designed as shown in
In the state of the art, there are various applications in which the spring rate is changed by using a single leaf spring. Such applications create a contact point with the vehicle chassis. The leaf spring comes into contact with the contact point on the chassis as a result of exceeding the displacement threshold due to the load imposed on the leaf spring, thereby increasing the spring rate. However, such use is not suitable for every vehicle type. In case it is indeed suitable, it incurs additional costs since it requires installing an additional part. Furthermore, the additional part positioned on the chassis generates a continuous impact on the leaf spring as the vehicle shakes, thereby inducing fatigue and deformation in the material of the leaf spring.
The present invention relates to leaf springs comprising a C spring designed so as to eliminate all the disadvantages in the state of the art. The object of the inventive leaf spring is to provide multiple spring rates independently of the manufacturing material by means of the improved design of the leaf spring.
The present invention allows for producing leaf springs from a single material, thereby reducing the amount of material used for manufacturing. Thus, the present invention is not only cost-saving but also allows for obtaining a product that is lighter when compared to multi-layered leaf springs used for obtaining similar varying spring rates. The present invention also reduces the carbon emission of the vehicle in which it is used, as it is lighter compared to leaf spring designs of the state of the art that comprise multiple layers.
The innovative geometric design of the inventive leaf spring allows for using the leaf spring without the need for replacing or interfering with a vehicle's available parts. In addition thereto, the present invention avoids strength losses occurring while mounting the additional layers since the inventive leaf spring is manufactured as a single piece. The present invention allows for eliminating undesired consequences in the state of the art such as the abrasion and/or fatigue of the material stemming from vibration-induced collision of the multi-layered leaf springs.
The main body of the inventive leaf spring does not sustain any damage as the inventive leaf spring does not utilize any products like gummy bumpers, etc. in order to change the spring rate. Thus, when the inventive leaf spring is installed on a vehicle, it may have a prolonged lifetime.
The inventive leaf spring that provides multiple spring rates should be evaluated in light of the following figures in order to ensure that the innovations made to achieve the aforementioned objects are understood clearly,
Wherein;
Respective components of the inventive leaf spring that provides multiple spring rates are enumerated in said figures in order to provide a better understanding of the present invention
Wherein;
The present invention is a leaf spring designed as a vehicle suspension element, and it is based on the parallel operation of areas with different spring rates. The inventive single-piece leaf spring comprises a long spring (1) and a short spring (2). Definitions of the long spring (1) and the short spring (2) are based on the geometrical shapes thereof and said long spring (1) and short spring (2) constitute the two different regions of the same spring. Chassis connection areas (5) serving as areas for connecting the leaf spring to the vehicle chassis are located at both ends of the leaf spring, i.e. at the end portions of the long spring (1) and the short spring (2). (
The spring rate of the inventive leaf spring is based on the resultant value of spring rates of said long spring (1) and short spring (2) up to the determined displacement value. Spring rates of both the long spring (1) and the short spring (2) depend on the geometric characteristics and material properties thereof. A force-displacement chart pertaining to the spring rate value up to the determined displacement value of the leaf spring is obtained as illustrated in
Subsequent to the interaction of the point B (4) on the long spring (1) and the point A (3) on the short spring (2), the point B (4) on the long spring (1) serves as a point of support and eliminates the influence of the spring rate of the short spring (2) on the total spring rate almost completely. The unique aspect of the present invention is that it is capable of achieving a different spring rate by directly interacting with the single-piece leaf spring. Thus, the desired force-displacement chart may be obtained by merely changing the geometry and/or the material properties of the short spring (2) and/or the long spring (1) without the need for any external point of support in addition to the spring. The present invention is described with an example given below in order to provide a better understanding of the inventive product.
kT≅k1
As shown in the example above, in cases where the displacement value is not exceeded, spring rates of the long spring (1) and the short spring (2) function as if they are connected in parallel to one another and accordingly, the resultant spring rate takes a smaller value. On the other hand, in cases where the critical displacement value is exceeded, the point A (3) interacts with the point B (4), and the short spring (2) is disabled as a result of this interaction. Thus, the total spring rate of the leaf spring roughly equals the spring rate of the long spring (1), thereby increasing the total spring rate. Accordingly, the force-displacement chart shown in
Another technical problem solved by the present invention is eliminating the use of spring shackles on leaf springs. In the state of the art, the length of the leaf spring increases due to the stretching of the leaf spring under load. Using spring shackles in at least one chassis connection area is necessary in order to tolerate this increase in length. The illustration provided in
The present invention described above has alternative applications. As seen in
In another application, a spring shackle (8) is connected to the chassis connection area (5) positioned to the end of the short spring (2). The end portion of the short spring (2) of the inventive leaf spring is connected to the chassis by means of the spring shackle (8). The spring shackle's (8) capability of rotating around its axis facilitates the short spring's (2) movement on the x-axis. Thus, the elongation stemming from the stretching occurring on the leaf spring under load may be tolerated.
As illustrated in
An alternative application is illustrated in
The essential point about the present invention is that, once the specified displacement value is exceeded, the short spring (2) is deactivated as a result of the interaction between the point A (3) and the point B (4). Accordingly, as illustrated in
As illustrated in
As the inventive leaf spring may be manufactured from a single material based on user preference, the long spring (1) and the short spring (2) may be manufactured from different materials. This varies depending on the total number of spring rates needed.
This application is the national phase entry of International Application No. PCT/TR2020/050891, filed on Sep. 28, 2020, the entire contents of which are incorporated herein by reference.
Filing Document | Filing Date | Country | Kind |
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PCT/TR2020/050891 | 9/28/2020 | WO |