FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
The patent Rule, 2003
COMPLETE SPECIFICATION (See section 10 and rule 13)
“ELECTROMECHANICAL POWER STRUT”
MINDA CORPORATION LIMITED of E-5/2, Chakan Industrial Area, Phase- III M.I.D.C. Nanekarwadi, Tal: Khed, Dist., Pune, Maharashtra, 410-501, India
The following specification particularly describes the invention and the manner in which it is to be performed.

FIELD OF INVENTION
The present disclosure generally relates to an electromechanical power strut. Particularly, but not exclusively, the present disclosure relates to an electromechanical power strut configured to assist in opening and closing doors, tailgate and bonnet of a vehicle.
BACKGROUND OF DISCLOSURE
Power lift gate system is an electronic trunk opener that allows the user to open the trunk of the vehicle hands-free and by just waving the leg under the rear bumper of the vehicle, in presence of a smart key fob in the vicinity of the vehicle access unit. Other offline options of opening the trunk include pressing a button on key fob driven by remote keyless entry or mechanically actuating the tail gate by pressing the button from the vehicle dashboard or cabin. From a convenience perspective, the user is not required to put down the bags or other items, in order to open the trunk of the vehicle. The power lift gate system, thus, reduces the effort of the user and also aids in reduction of time.
Typically, a power lift gate system includes a power strut, an ECU, a kick sensor, and an anti pinch sensor (optional). In most of the power lift gate systems, mono rated compression spring assists a motor of the system in opening the trunk and provides required support to the trunk in fully open condition. During an operation of the power lift gate system, output force is delivered jointly by the motor and a lead screw mechanism. However, during the initial opening travel of the trunk, which incurs inertial change of position of the trunk from a rest position to an open position, high output force is generally required. This requirement arises due to single rate compression spring, trunk and vehicle body kinematics, pressure difference between inside and outside of the car and latch restriction.
One known prior art solution comprises increasing the power of the motor, that is, adopting the motor of higher ratings to aid the high initial force in the operation from the close position to the open position. However, said solutions poses drawbacks, like, requirement of larger, high-capacity motor, which increases the size and weight of the power gate strut and requires more space to accommodate. Additionally, the force

delivered by high rating motor during the opening operation may not be required during the rest of the trajectory as the inertia of motion do not mandate the same force in the remaining path of the trajectory. Therefore, the higher power and higher rating of the motor remains underutilized during the latter travel of the strut.
Another known prior art solution incorporates an elastic force member along with the single-rated compression spring to provide additional force during the trunk's initial opening. This arrangement involves complex components like a piston-cylinder arrangement, seals, piston rod, guide disc, and gas/oil, acting as a pneumatic or hydraulic spring. However, this approach has drawbacks such as critical component selection, sealing design, increased weight of additional parts, closed length, and decreased product reliability due to the complexity of assembly.
Yet another prior art solution involves adding an additional single-rated compression spring with a different spring rate than the primary compression spring. This additional spring delivers the additional force required during the initial opening of the trunk from the fully closed position. However, this solution increases assembly complexity, overall cost, and inventory handling.
None of the prior art solutions describe the use of a biasing element having variable stiffness to address the high initial force requirement in the power strut during opening and closing the doors, tailgate and bonnet.
SUMMARY OF THE DISCLOSURE
The present disclosure overcomes one or more shortcomings of the prior art and provides additional advantages through the system as claimed in the present disclosure. Additional features and advantages are realized through the techniques of the present disclosure. Other embodiments and aspects of the disclosure are described in detail herein and are considered a part of the claimed disclosure.
In a non-limiting embodiment of the present disclosure, an electromechanical power strut for a vehicle is disclosed. The electromechanical power strut for a vehicle is configured to assist in opening and closing doors, tailgate or bonnet of the vehicle. The power strut comprises a longitudinal outer cover, a drive mechanism, a longitudinal

inner cover, a lead mechanism and a biasing element. The drive mechanism is operatively disposed within the longitudinal outer cover. The longitudinal inner cover is configured to be telescopically receivable inside the longitudinal outer cover. The lead mechanism is defined by two ends, of which one end is operatively coupled with the said drive mechanism and other end is secured with the longitudinal inner cover. The lead mechanism is configured to rotatably displace along with said longitudinal inner cover within said longitudinal outer cover. The biasing element is disposed inside said inner cover and engageably surrounding with the lead mechanism, said biasing element having variable stiffness. The biasing element is configured to deliver varying force levels during compression and decompression, for opening and closing the doors, tailgate or bonnet upon linear displacement of the lead mechanism.
In an embodiment of the present disclosure, the lead mechanism includes an actuation tube, a lead nut and a lead screw. The actuation tuber is operatively disposed inside the longitudinal inner cover and the biasing element engageably surrounds the said actuation tube. The lead screw has two ends, out of which one end of said lead screw is configured to be coupled with said drive mechanism and other end of said lead screw is coupled with said lead nut to enable said lead nut to linearly displace over the lead screw upon rotation of said lead screw to facilitate compression and decompression of said biasing element.
In an embodiment of the present disclosure, the lead screw is configured to rotate and displace said lead nut along with the length of said lead screw to compress and decompress said biasing element.
In an embodiment of the present disclosure, a linear movement of the lead nut over the lead screw facilitate extension and retraction of the actuation tube.
In an embodiment of the present disclosure, the lead mechanism comprises a shaft coupler to couple an output end of the drive mechanism to said lead screw to rotate said lead screw.
In an embodiment of the present disclosure, the biasing element is positioned in a longitudinal direction of the lead mechanism.

In an embodiment of the present disclosure, the biasing element is a multi-rated compression spring, operatively disposed inside longitudinal outer cover and longitudinal inner cover, and between drive mechanism and an end stopper respectively.
In an embodiment of the present disclosure, the drive mechanism is an electric motor.
In an embodiment of the present disclosure, the biasing element is selected from the group consisting of springs, elastomers, hydraulic elements, pneumatic springs, magnetic biasing elements, or screw mechanisms.
The foregoing summary is illustrative only and is not intended to be in any way limiting. In addition to the illustrative aspects, embodiments, and features described above, further aspects, embodiments, and features will become apparent by reference to the drawings and the following detailed description.
BRIEF DESCRIPTION OF DRAWINGS
Further aspects and advantages of the present invention will be readily understood from the following detailed description with reference to the accompanying figure(s). The figure(s) together with a detailed description below, are incorporated in and form part of the specification, and serve to further illustrate the embodiments and explain various principles and advantages, in accordance with the present invention wherein:
Figure 1 illustrates a perspective view of a rear portion of a vehicle comprising a tailgate and an electromechanical power strut, in accordance with an embodiment of the present disclosure;
Figure 2 illustrates a cross-sectional view of the electromechanical power strut of Figure 1, in accordance with an embodiment of the present disclosure;
Figure 3 illustrates an exploded view of the electromechanical power strut of Figure 2, in accordance with an embodiment of the present disclosure; and

Figure 4 illustrates a biasing element of the electromechanical power struct of Figure 2, in accordance with an embodiment of the present disclosure.
Skilled artisans will appreciate that elements in the drawings are illustrated for simplicity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the drawings may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.
DETAILED DESCRIPTION
While the invention is susceptible to various modifications and alternative forms, specific embodiment thereof has been shown by way of example in the figures and will be described in detail below. It should be understood, however that it is not intended to limit the invention to the particular forms disclosed, but on the contrary, the invention is to cover all modifications, equivalents, and alternative falling within the spirit and the scope of the invention.
Before describing in detail embodiments, it may be observed that the novelty and inventive step that are in accordance with the present disclosure resides in an electromechanical power strut for a vehicle. It is to be noted that a person skilled in the art can be motivated from the present disclosure and modify the various constructions of the electromechanical power strut, which may vary from vehicle to vehicle. However, such modification should be construed within the scope of the present disclosure. Accordingly, the drawings are showing only those specific details that are pertinent to understanding the embodiments of the present disclosure as not to obscure the disclosure with details that will be readily apparent to those of ordinary skill in the art having benefit of the description herein.
The terms “comprises”, “comprising”, or any other variations thereof, are intended to cover a non-exclusive inclusion, such that a setup, or a device that comprises a list of components does not include only those components but may include other components not expressly listed or inherent to such setup or device. In other words, one or more elements in a system or apparatus proceeded by “comprises… a” does not, without more constraints, preclude the existence of other elements or additional elements in the system or apparatus.

The following paragraphs describe the present invention with reference to Figures 1 – 4 according to an embodiment of the present disclosure.
Accordingly, the present disclosure relates to an electromechanical power strut for a vehicle. The electromechanical power strut is configured to not only reduce the overall load on the drive mechanism but also will help to select a compact drive mechanism with less weight and cost. Specifically, compact drive mechanism will help to reduce the overall package size of the power strut which will allow to mount it in tightest of the spaces available in the vehicle.
Figure 1 illustrates a rear portion of a vehicle (500) comprising a tailgate (100) and an electromechanical power strut (200). In an embodiment, the tailgate (100) may be used, e.g., for a trunk of the vehicle. In Figure 1, the tailgate (100) is shown in an open position, while the rest of the vehicle is omitted for sake of clarity. In the open position, the tailgate (100) extends almost vertically upwards from a lock side to a hinge side. On the hinge side, two hinges of a hinge mechanism are connected to the tailgate (100), whereby the tailgate (100) is connectable to a body of the vehicle. For opening and closing of the tailgate (100), an electromechanical power strut (200) is used, which delivers efficient force during the complete trajectory travel of the tailgate (100). The electromechanical power strut (200) includes a plurality of ball socket end mountings (150) for assembling the electromechanical power strut (200) to the vehicle. One end of the electromechanical power strut (200) is connected to the body of the vehicle, and another end is connected to the tailgate (100), via a plurality of ball socket end mountings (150). The electromechanical power strut (200) is configured to assist in opening and closing of said tailgate (100).
In an embodiment, the electromechanical power strut (200) may also assist in opening and closing of doors and bonnet of the vehicle, without limiting the scope of the invention.
Figure 2 illustrates the electromechanical power strut (200) for assisting in opening and closing the tailgate (100) of the vehicle, in accordance with the preferred embodiment of the present disclosure. The electromechanical power strut (200)

comprises a longitudinal outer cover (212) and a longitudinal inner cover (214). The longitudinal inner cover (214) is configured to be telescopically receivable inside the longitudinal outer cover (212). A drive mechanism (220) of the electromechanical power strut (200) is operatively disposed within the longitudinal outer cover (212). In an embodiment of the present disclosure, the drive mechanism (220) is an electric motor.
The electromechanical power strut (200) further comprises a lead mechanism (300) which is defined by two ends. One end is operatively coupled with the said drive mechanism (220) and the other end is secured with the longitudinal inner cover (214). The lead mechanism (300) is configured to rotatably displace along with said inner cover within said longitudinal outer cover (212).
Further, a biasing element (250) is disposed inside the longitudinal inner cover (214) of the electromechanical power strut (200). The biasing element (250) is positioned in a longitudinal direction of the electromechanical power strut (200).
Referring to Figure 4, according to the present disclosure, the biasing element (250) is configured to have variable stiffness. In an embodiment, the biasing element (250) may be adapted to deliver two output forces required for operation of the electromechanical power strut (200). The biasing element (250) may be adapted to deliver varying force levels during compression and decompression, for opening and closing the doors, tailgate (100) or bonnet upon the linear displacement of the lead mechanism (300). In accordance with the present disclosure, the biasing element (250) with variable stiffness provides more force during an initial opening travel of the power strut, thereby reducing a load on the drive mechanism (220) while opening the tailgate (100).
In an embodiment of the present invention, the biasing element (250) is selected from the group consisting of springs, elastomers, hydraulic elements, pneumatic springs, magnetic biasing elements (250), or screw mechanisms.
The electromechanical power strut (200) may further be coupled with an electronic control unit, a processor and a memory (not shown) to control the operation of the drive mechanism (220). The processor may be implemented as one or more microprocessors,

microcomputers, microcontrollers, digital signal processors, central processing units, state machines, logic circuitries, and/or any devices that manipulate signals based on operational instructions. Among other capabilities, the processor may be configured to fetch and execute computer-readable instructions stored in the memory.
Figure 3 illustrates an exploded view of the electromechanical power strut (200). The lead mechanism (300) comprises an actuation tube (310), a lead nut (312) and a lead screw (316). The actuation tube (310) is operatively disposed inside the longitudinal inner cover (214) and the biasing element (250) engageably surrounds the actuation tube (310). For opening and closing the tailgate (100), an output of the drive mechanism (220) is captured by the lead screw (316), thereby, rotating the lead screw (316). The lead screw (316) includes two ends, one end of the lead screw (316) is coupled with an output end of the drive mechanism (220) via a shaft coupler (350). Other end of the lead screw (316) is coupled with the lead nut (312) to enable said lead nut (312) to linearly displace along with the length of the lead screw (316) upon rotation of said lead screw (316) to facilitate compression and decompression of said biasing element (250).
In an embodiment, the lead nut (312) is disposed around the lead screw (316) such that external threads of the lead screw (316) mesh with internal threads of the lead nut (312). Rotation of the lead screw (316) by the drive mechanism (220) facilitates a linear movement of the lead nut (312) along the length of the lead screw (316). Further, the actuation tube (310) is coupled with the lead nut (312) and is adapted to move linearly with the lead nut (312). In an embodiment, the rotation of the lead screw (316) by the drive mechanism (220) facilitates the linear movement of the lead nut (312) and the actuation tube (310) along a longitudinal direction of the lead screw (316).
In a working implementation of the electromechanical power strut (200), when the tailgate (100) is closed, the biasing element (250) is in a compressed state. For opening the tailgate (100), the electronic control unit sends one or more signals to the drive mechanism (220) to actuate the lead screw (316). In an embodiment, the drive mechanism (220) rotates the lead screw (316), at an output end of the drive mechanism (220). The lead screw (316) enables the lead nut (312) and the actuation tube (310) to linearly displace along with the length of the lead screw (316), to facilitate decompression of said biasing element (250). As the lead screw (316) drives the lead

nut (312) and the actuation tube (310) to extend outward to lift the tailgate (100), the recoil from the biasing element (250) provides a push force to support a part of the weight of the tailgate (100) to reduce the load on the drive mechanism (220).
Further, when the tailgate (100) is open, the biasing element (250) is in a decompressed state. For closing the tailgate (100), the electronic control unit sends one or more signals to the drive mechanism (220) to actuate the lead screw (316). In an embodiment, the drive mechanism (220) rotates the lead screw (316), at the output end of the drive mechanism (220). The lead screw (316) enables the lead nut (312) and the actuation tube (310) to linearly displace along with the length of the lead screw (316), to facilitate compression of said biasing element (250). As the lead screw (316) drives the lead nut (312) and the actuation tube (310) to retract the tailgate (100), the biasing element (250) provides a retraction which reduces the load on the drive mechanism (220).
The electromechanical power strut (200) of the present disclosure is configured to not only reduce the overall load on the drive mechanism (220) but also will help to select a compact drive mechanism (220) with less weight and cost. Specifically, the compact drive mechanism (220) will help to reduce the overall package size of the electromechanical power strut (200) which will allow to mount it in tightest of the spaces available in the vehicle.
List of reference numerals:

100 Tailgate
200 Electromechanical power strut
212 Longitudinal outer cover
214 Longitudinal inner cover
220 Drive mechanism
300 Lead mechanism
250 Biasing element
310 Actuation tube
312 Lead nut
316 Lead screw
350 Shaft coupler

Equivalents:
The embodiments herein and the various features and advantageous details thereof are explained with reference to the non-limiting embodiments in the description. Descriptions of well-known components and processing techniques are omitted so as to not unnecessarily obscure the embodiments herein. The examples used herein are intended merely to facilitate an understanding of ways in which the embodiments herein may be practiced and to further enable those of skill in the art to practice the embodiments herein. Accordingly, the examples should not be construed as limiting the scope of the embodiments herein.
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 embodiments as described herein.
Throughout this specification the word “comprise”, or variations such as “comprises” or “comprising”, will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.
The use of the expression “at least” or “at least one” suggests the use of one or more elements or ingredients or quantities, as the use may be in the embodiment of the disclosure to achieve one or more of the desired objects or results.
Any discussion of documents, acts, materials, devices, articles and the like that has been included in this specification is solely for the purpose of providing a context for the disclosure. It is not to be taken as an admission that any or all of these matters form a

part of the prior art base or were common general knowledge in the field relevant to the disclosure as it existed anywhere before the priority date of this application.
The numerical values mentioned for the various physical parameters, dimensions or quantities are only approximations and it is envisaged that the values higher/lower than the numerical values assigned to the parameters, dimensions or quantities fall within the scope of the disclosure, unless there is a statement in the specification specific to the contrary.
While considerable emphasis has been placed herein on the particular features of this disclosure, it will be appreciated that various modifications can be made, and that many changes can be made in the preferred embodiments without departing from the principles of the disclosure. These and other modifications in the nature of the disclosure or the preferred embodiments will be apparent to those skilled in the art from the disclosure herein, whereby it is to be distinctly understood that the foregoing descriptive matter is to be interpreted merely as illustrative of the disclosure and not as a limitation.

WE CLAIM:
1. An electromechanical power strut (200) for a vehicle, said electromechanical
power strut (200) configured to assist in opening and closing doors, tailgate
(100) or bonnet of the vehicle, said electromechanical power strut (200)
comprising:
a longitudinal outer cover (212);
a drive mechanism (220) operatively disposed within said longitudinal outer cover (212);
a longitudinal inner cover (214) configured to be telescopically receivable inside said longitudinal outer cover (212);
a lead mechanism (300) defined by two ends, one end operatively coupled with said drive mechanism (220) and other end secured with the longitudinal inner cover (214), said lead mechanism (300) configured to rotatably displace along with said inner cover within said longitudinal outer cover (212); and
a biasing element (250) disposed inside said longitudinal inner cover (214) and engageably surrounding with said lead mechanism (300), said biasing element (250) having variable stiffness,
wherein said biasing element (250) configured to deliver varying force levels during compression and decompression, for opening and closing the doors, tailgate (100) or bonnet upon linear displacement of said lead mechanism (300).
2. The electromechanical power strut (200) as claimed in claim 1, wherein said
lead mechanism (300) includes:
an actuation tube (310) operatively disposed inside said longitudinal inner cover (214), said biasing element (250) engageably surrounding said actuation tube (310);
a lead nut (312); and
a lead screw (316) having two ends, one end of said lead screw (316) configured to be coupled with said drive mechanism (220) and other end of said lead screw (316) coupled with said lead nut (312) to enable said lead nut (312) to linearly displace over the lead screw (316) upon rotation of said lead screw

(316) to facilitate compression and decompression of said biasing element
(250).
3. The electromechanical power strut (200) as claimed in claim 2, wherein said lead screw (316) is configured to rotate and displace said lead nut (312) along with the length of said lead screw (316) to compress and decompress said biasing element (250).
4. The electromechanical power strut (200) as claimed in claim 3, wherein a linear movement of the lead nut (312) over the lead screw (316) facilitates extension and retraction of the actuation tube (310).
5. The electromechanical power strut (200) as claimed in claim 2, wherein the lead mechanism (300) comprises a shaft coupler (350) to couple an output end of the drive mechanism (220) to said lead screw (316) to rotate said lead screw (316).
6. The electromechanical power strut (200) as claimed in claim 1, wherein the biasing element (250) is positioned in a longitudinal direction of the lead mechanism (300).
7. The electromechanical power strut (200) as claimed in claim 1, wherein the biasing element (250) is a multi-rated compression spring, operatively disposed inside the longitudinal outer cover (212) and the longitudinal inner cover (214), and between drive mechanism (220) and an end stopper respectively.
8. The electromechanical power strut (200) as claimed in claim 1, wherein the drive mechanism (220) is an electric motor.
9. The electromechanical power strut (200) as claimed in claim 1, wherein said biasing element (250) is selected from the group consisting of springs, elastomers, hydraulic elements, pneumatic springs, magnetic biasing elements (250), or screw mechanisms.