FIELD OF THE INVENTION
The present invention relates to suspension systems used on automotive vehicles and more specifically to a regenerative suspension system that is adapted for damping vertical acceleration generated during motion and capable of transforming linear displacement to electrical energy.
BACKGROUND OF THE INVENTION
A conventional suspension or shock absorber system has a coil spring which stores strain energy upon occurrence of jounce and releases it during rebound. However, a coil spring alone stores and releases its energy almost instantly which triggers a simple harmonic like motion for linked suspended mass. The oscillation continues for a longer period as the energy is slowly dissipated by the spring alone. This is where a dampener plays an indispensable role in absorbing the energy, especially during rebounds. Dampers are hydraulic devices designed to absorb more energy during rebound than jounce. For example, in a suspension system used on a two wheeled vehicle, this damping bias varies from 20/80 to 5/95 for jounce and rebound respectively.
Conventional coil spring suspensions provide passive damping by dissipating jounce and rebound energy in the form of heat. The energy conversion happens when a perforated piston reciprocates in a viscous fluid based damper. During this phenomenon, the fluid is forced through perforations inducing viscous drag on the piston, thereby converting mechanical energy to heat. This energy conversion is

imperative for damping simple harmonic motion. However, discarding the resultant heat to atmosphere is a waste of recoverable energy.
A vehicle suspension under normal condition operates at low amplitude and high frequency oscillations. These oscillations are induced in unsuspended mass by road profile (paved, gravel, off-road) and tire threads through contact patch. The oscillation frequencies are more pronounced at higher speeds than at lower speeds due to high centrifugal forces contributing to changes in rigidity and dimensional characteristics of the side walls of the tire. In contrast, at lower speeds the tire absorbs a major share of the road profile induced high frequency oscillations thus allowing low frequency oscillations to remain dominant.
Suspension oscillations are always induced whenever a vehicle is in a state of motion, irrespective of its speed. Even on flattest surfaces like glass, tire threads induce vibrations of low amplitude and high frequency. As vehicle unsuspended mass is always under oscillation with respect to the suspended mass, their continuous relative motion can effectively be leveraged to harness energy by regenerative systems to enhance the overall efficiency of the vehicle. Regenerative suspension systems that are capable of converting linear displacement into useful energy are known. The known systems while using the forces of magnetism to dampen the vertical acceleration generated during vehicle motion tend to become less effective when the road profile turns aggressive (off-road). Another known way of varying the damping characteristics is by inducing electrical power into the solenoid thereby altering the magneto-motive characteristics of the regenerative suspension system. The main drawback associated with such a known system is the

need for a large power source that has a higher power rating. Another known solution is the use of a magneto - rheological fluid which aids in varying the damping characteristics. This solution adds to the overall cost of the regenerative suspension system as it requires complex real time computing hardware for its effective functioning. Besides, the energy recovered is mostly spent in operating its complex hardware. There is a strong felt need for a regenerative suspension system that overcomes the drawbacks associated with the known systems.
It is therefore the object of the present invention to provide a regenerative suspension system that is capable of generating electrical energy while simultaneously dampening the vertical acceleration.
It is another object of the present invention to provide a regenerative suspension system that is adaptable to the road profile.
It is another object of the present invention to provide a regenerative suspension system that can effectively harness the energy otherwise wasted in the form of heat.
It is also an object of the present invention to increase the overall efficiency of the vehicle especially during high speeds.
It is yet another object of the present invention to facilitate continuous generation of power when the vehicle is in a state of motion.
It is also an object of the present invention to provide a regenerative suspension system that is cost effective and maintenance free.

It is another object of the present invention to provide a regenerative suspension system that does not require a magneto rheological fluid for varying the damping characteristics.
SUMMARY OF THE INVENTION
The present invention is directed to a regenerative suspension system for an automotive vehicle that is capable of generating electrical energy while simultaneously contributing towards damping the vertical acceleration generated during the motion of the vehicle. In one aspect of an invention, the regenerative suspension system comprises a coil spring biasedly coupling a suspended portion of the vehicle to an unsuspended portion of said vehicle. There is provided a magneto-motive damping system arranged inside a housing axially coupled to the coil spring and having a linear generator for transforming the linear displacement into electrical energy and simultaneously damping the vertical acceleration. The regenerative suspension system is further provided with a fluid damping system arranged inside the housing and configured to operate at or above a threshold vertical acceleration and is operatively coupled to the magneto-motive damping system. The fluid damping system is provided with a regulator for varying the fluid pressure within the fluid damping system as a function of vertical acceleration acting on the unsuspended portion of the vehicle.

The housing of the regenerative suspension system comprises an upper chamber, a lower chamber and a lower mounting point adjoining the lower chamber and located external to the housing.
The magneto-motive damping system and the fluid damping system are operatively coupled by means of a linearly displaceable piston arrangement extending longitudinally through the housing and having a free end coupled to the upper mounting point and another end carrying a perforated piston dividing the lower chamber into at least two compartments.
The linear generator is arranged inside the upper chamber and having a ferrous core formed by a plurality of spacers carrying a plurality of annular magnets stacked coaxially. The ferrous core is axially mounted on the piston arrangement so as to allow linear displacement of the ferrous core relative to a solenoid thereby transforming the linear displacement to electrical energy and simultaneously damping the vertical acceleration.
The regulator further comprises a flow path fluidly connecting the at least two compartments in the lower chamber and a valve disposed to intercept the flow path.
The valve varies the fluid pressure in proportion to residual vertical acceleration above a threshold vertical acceleration generated during motion of the vehicle.
The valve assumes an inoperative configuration when the vertical acceleration is below a threshold vertical acceleration.

The valve assumes an operative configuration when the vertical acceleration is equal to a threshold vertical acceleration.
The valve assumes a fully operative configuration when the vertical acceleration is above a threshold vertical acceleration.
The vertical acceleration is measured by means of an accelerometer positioned on the unsuspended portion of the vehicle.
The vertical acceleration is measured by means of an accelerometer positioned on the housing.
The valve is operated by means of a microcontroller receiving an input signal from the accelerometer.
The valve is a solenoid actuated check valve.
A self-propelled vehicle having a power source, at. least a pair of ground engaging wheels with at least one of said ground engaging wheels propelled by means of a drive received from said power source is provided with a regenerative suspension system that is adapted for damping vertical acceleration generated during motion and capable of transforming linear displacement to electrical energy.
BRIEF DESCRIPTION OF THE DRAWINGS
The regenerative suspension system of the present disclosure will now be described with the help of accompanying drawings in which:

Figure 1 illustrates a schematic representation showing the regenerative suspension system coupling the suspended and unsuspended portions of the vehicle.
Figure 2 illustrates a sectional view of the suspension system.
Figure 3 illustrates an enlarged sectional view of the magneto - motive damping system having a linear generator.
Figure 4 illustrates an enlarged sectional view of the linear generator showing the realignment of magnetic polarity in the ferrous core.
Figure 5 illustrates a schematic representation of electrical circuitry to harness the electrical energy from the solenoid.
Figure 6 illustrates a top sectional view of the housing showing the arrangement of piston in the lower chamber.
Figure 7 illustrates an enlarged sectional view of viscous damping system.
Figure 8 illustrates a schematic block diagram for controlling the valve opening.
Figure 9 illustrates a sectional view of fluid damping system indicting the valve in an inoperative configuration.
Figure 10 illustrates a sectional view of fluid damping system indicting the valve in a partially operative configuration.
Figure 11 illustrates a sectional view of fluid damping system indicting the valve in an operative configuration.

DETAILED DESCRIPTION OF THE INVENTION
Hereinafter the invention will be described in more detail with reference to an embodiment of the present invention.
Now, referring to Figure 1, there is shown a schematic representation of an arrangement in a vehicle V having a chassis C mounted on an axle A to which is connected at least a pair of ground engaging wheels W. The portion of the vehicle V that is directly subjected to the effects of undesirable vertical acceleration generated when the vehicle V is in motion on an uneven ground surface is called the unsuspended portion S1. An exemplary component that is part of the unsuspended portion S1 of the vehicle V is the ground engaging wheels W. The portion of the vehicle V that is separated from the effects of undesirable vertical acceleration generated when the vehicle V travels on an uneven ground surface is called the suspended portion S2. The suspended portion S2 comprises the chassis C as well as myriad other components (not listed for the sake of brevity) that are mounted on the chassis C. The suspended portion S2 of the vehicle V tend to receive dampened and low amplitude vibrations thereby positively affecting the driving comfort and safety. The unsuspended portion S1 is separated from the suspended portion S2 by means of a regenerative suspension system 10 which hereinafter, will simply be called a suspension system 10. The suspension system 10 of the present invention is adapted for damping vertical acceleration generated during motion of the vehicle V and is capable of transforming linear displacement to electrical energy.

The suspension system 10 of the present invention will further be described in detail with specific reference to Figure 2. The suspension system 10 comprises a coil spring 15, a magneto-motive damping system 20, a housing 30 and a fluid damping system 60. The suspension system 10 further comprises a piston arrangement 32 having a free end and another end carrying a piston 34. There is also provided an upper mounting point 36 rigidly positioned above an upper stopper 38. A lower mounting point 37 as well as a lower stopper 39 are also provided. The housing 30 of the present embodiment has a cylindrical configuration. The housing 30 is divided into an upper chamber 40 and a lower chamber 42. The housing 30 also has an external upper opening 44 and an internal lower opening 46. The magneto -motive damping system 20 comprises a linear generator G functionally arranged in the upper chamber 40 of the housing 30. The fluid damping system 60 of the present invention comprises a regulator R arranged proximate to and in fluid communication with the lower chamber 42 of the housing 30.
The various components of the liner generator G will be discussed with specific reference to Figure 3, wherein there is provided a ferrous core 50 comprising a plurality of annular magnets 52 each separated by means of annular spacers 54. There is also provided a solenoid 56 arranged inside the upper chamber 40 of the housing 30.
The arrangement and interrelationship among various components of the suspension system 10 will hereinafter be explained in detail again with specific reference to Figures 2 and 3. As shown in Figure 2, the upper mounting point 36

rigidly attached to the upper stopper 38 connects the suspended portion S2 of the vehicle V to the suspension system 10. The upper stopper 38 has a circular configuration with the over-side connected to the upper mounting point 36 and the underside receiving the free end of the piston arrangement 32. The lower mounting point 37 provided on extreme downstream side of the housing 30 connects the unsuspended portion S1 of the vehicle to the suspension system 10. The lower stopper 39 is a flanged projection provided on the outer surface of the housing 30 and located longitudinally away from the upper mounting point 36 and proximate to the lower mounting point 37. The coil spring 15 is mounted coaxially over the outer surface of the housing 30 and is restrained in between the circularly configured upper stopper 38 and the lower stopper 39 in the shape of a flanged projection. The free end of the piston arrangement 32 is received inside the internal lower opening 46 and passes through the external upper opening 44 and extends from there to be connected to the underside of the upper stopper 38. The piston 34 carried on the other end of the piston arrangement 32 slides linearly along the walls of the lower chamber 42. It is to be noted that the piston 34 assumes a geometrical cross-section analogous to the geometrical cross-section of the lower chamber 42. In the present embodiment, the piston 34 and the lower chamber 42 are circular in cross-section. The piston arrangement 32 together with the piston 34 operatively couples the magneto-motive damping system 20 and the fluid damping system 60. The arrangement of various components of the magneto - motive damping system 20 will be elucidated in detail with reference to Figure 3, wherein the ferrous core 50 comprises the annular magnets 52 and the spacers 54. The ferrous core 50 is

formed by stacking the spacers 54 one above the other with each of the annular magnets 52 separating two spacers 54, 54. In the present embodiment, the annular magnets 52 and the spacers 54 assume a disc like configuration with a circular opening in their respective centres so as to allow the piston arrangement 32 to pass through the circular opening thereby retaining the ferrous core 50 firmly inside the upper chamber 40 of the housing 30. The solenoid 56 in the present embodiment is a coil of wire wound around the ferrous core 50 in the form of a closely spaced helix. The solenoid 56 is wounded over a metallic core which is not expressly shown in the drawings as it is already known very well in the art.
The construction of the linear generator G will further be explained in detail with reference to Figure 4. The spacers 54 magnetically interacts with the annular magnets 52 placed above and below a given spacer 54 resulting in the spacers 54 attaining magnetic polarity. The spacers 54 are configured so as to form a cavity surrounded by a wall on either sides. This configuration of the spacers 54 provides for receiving the annular magnets 52 inside the cavities on either sides. In an exemplary arrangement, the annular magnets 52 exhibit North polarity on one side surface (N-N) and South polarity on the other side surface (S-S). The annular magnets 52 are arranged in a manner such that the side surfaces carrying like poles face each other with the first spacer 54A sandwiched in between. Upon stacking the annular magnets 52 with the spacer 54A in between, the spacer 54A attain magnetic polarity similar to the polarity exhibited by the adjoining annular magnets 52. In the proposed arrangement, as we proceed top-down the circumferential ends of the first spacer 54A assume one specific pole (S) and the centres assume an opposing

pole (N). The second spacer 54B has its circumferential ends assuming a polarity (N) that is opposite to the polarity assumed by the circumferential ends of the first spacer 54A. The centres of the second spacer 54B assume a polarity (S) that is opposite to the polarity (N) exhibited by the centres of the first spacer 54A. This arrangement cascades from the first to the last spacers 54 enabling the ferrous core 50 to create radial lines of magnetic flux. The ferrous core 50 is firmly connected to the piston arrangement 32 such that the ferrous core 50 is subjected to a linear displacement when the piston arrangement 32 undergoes a linear displacement due to vertical acceleration. The proposed arrangement maximizes the magnetic flux density within the solenoid 54 resulting in higher amounts of power being harnessed by the linear generator G due to vertical acceleration while the vehicle V is in motion.
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The ends of the solenoid 54 are connected to respective terminals T, T which are in turn connected to a rectifier unit 55 as shown in Figure 5. The rectifier unit 55 functions in a known way so as to convert alternating current (AC) input into direct current (DC) output delivered through the positive and negative terminals in the circuit.
The fluid damping system 60 of the suspension system 10 will further be described in detail with specific reference to Figures 6 and 7. The piston 34 comprises a plurality of spaced apart perforations O. In the present embodiment, the regulator R comprises a flow path 62 and a valve 64. The piston 34 having plurality of spaced apart perforations O divides the lower chamber 42 into two fluidly communicating

compartments 44 and 45. The portion of the lower chamber 42 above the piston 34 when the suspension system 10 is in its operative upright position is the first compartment 44. The portion of the lower chamber 42 below the piston 34 when the suspension system 10 is in its operative upright position is the second compartment 45. The fluid is exchanged between the first compartment 44 and the second compartment 45 via the perforations O located on the piston 34. Alternatively, the fluid is exchanged between the first compartment 44 and the second compartment 45 also via the flow path 62 of the regulator R as shown in Figure 7. The valve 64 intercepts the flow path 62 at a designated location thereby regulating the amount of fluid exchanged between the first compartment 44 and the second compartment 45 depending on the operating characteristics of the valve 64. The valve 64 is provided with an actuator 65 for controlling its operation.
As shown in Figure 8, the actuator 65 of the valve 64 is functionally connected to the microcontroller 68. The microcontroller 68 receives an input corresponding to the magnitude of vertical accelerations experienced by the vehicle V through an accelerometer 66 functionally connected to the microcontroller 68. The accelerometer 66 is disposed anywhere on the unsuspended portion S1 of the vehicle V in order to record the true and non-dampened vertical acceleration. Based on the input received from the accelerometer 66, the microcontroller 68 issues a signal to the actuator 65 for operating the valve 64.
The working of the invention will hereinafter be explained with reference to the foregoing description of the present embodiment. When the vehicle V is in motion,

the unsuspended portion S1 experiences undesirable vertical acceleration leading to transfer to vibrations to the suspension system 10. The suspension system 10 absorbs and dampens the vertical acceleration received from the unsuspended portion S1 and converts the vertical acceleration into electromotive force and heat thereby transferring only a portion of the received vertical acceleration to the suspended portion S2.
The vertical acceleration acting on the suspension system 10, subjects the coil spring 15 to compression as the upper stopper 38 linearly displaces itself downwards. The piston arrangement 32 connected to the upper stopper 38 acquires a linear motion allowing itself to be displaced inside the housing 30. The work done against compressing the coil spring 15 is instantly stored and gradually released by the combined action of the magneto-motive damping system 20 and the fluid damping system 60.
The working of the magneto-motive damping system will be explained in detail. The ferrous core 50 firmly joined to the piston arrangement 32 moves relative to the solenoid 56 in response to the external vertical acceleration causing the linear displacement. The ferrous core 50 directly connected to the piston arrangement 32 generates radial lines of magnetic flux around the solenoid 56. The linear displacement of the ferrous core 50 relative to the solenoid 56 induces a change in magnetic flux inducing an electromotive force in the solenoid 56 thereby generating electrical energy to be harnessed by the terminals T, T and delivered as direct current after rectification. The electromotive force induced in the solenoid 56 is

analogous to the magneto-motive force that acts on the ferrous core 50 in a direction opposite to the direction in which the ferrous core 50 attached to the piston arrangement 32 moves within the housing 30. The magneto-motive force generated acting on the ferrous core 50 causes resistance to movement of the ferrous core 50 in turn causing resistance to the piston arrangement 32 thereby absorbing the energy induced due to the vertical acceleration.
When the vertical acceleration acting on the suspension system 10 as sensed by the accelerometer is below a threshold value, the valve 64 remains in an inoperative configuration characterized by the valve remaining fully open allowing the free flow of fluid in the flow path 62, as shown in Figure 9. This condition represents the normal operating condition of the suspension system 10 where the magneto -motive damping system 20 effectively dampens the vertical acceleration acting on the vehicle V. This condition can be observed when the vehicle V is moving on a paved surface. During this condition, the exchange of fluid between the first compartment 44 and the second compartment 45 takes place both through the perforations O on the piston 34 as well as through the unrestricted flow path 62 of the regulator R.
. When the vertical acceleration acting on the suspension system 10 as sensed by the accelerometer equal the threshold value, the valve 64 starts to assume an operative configuration characterized by the valve remaining partially open allowing the restricted flow of fluid in the flow path 62, as shown in Figure 10. This condition represents an aggressive operating condition of the suspension system 10 where the

magneto - motive damping system 20 alone cannot effectively dampens the vertical acceleration acting on the vehicle V. This condition can be observed when the vehicle V is moving on a gravel surface. During this condition, the exchange of fluid between the first compartment 44 and the second compartment 45 continue to take place both through the perforations O on the piston 34 as well as through the partially restricted flow path 62 of the regulator R.
When the vertical acceleration acting on the suspension system 10 as sensed by the accelerometer largely exceeds the threshold value, the valve 64 assumes an inoperative configuration characterized by the valve remaining fully closed allowing no flow of fluid in the flow path 62, as shown in Figure 11. This condition represents a harsh operating condition of the suspension system 10 where the magneto - motive damping system 20 no longer effectively dampens the vertical acceleration acting on the vehicle V. This condition can be observed when the vehicle V is moving on an off-road surface. During this condition, the exchange of fluid between the first compartment 44 and the second compartment 45 continue to take place only through the perforations O on the piston 34 as the flow path 62 is totally restricted by the valve 64 in its fully operative configuration.
The proposed regenerative suspension system for a vehicle adapted for damping vertical acceleration generated during motion and capable of transforming linear displacement to electrical energy has several technical advantages including but not limited to the realization of:

A regenerative suspension system that is capable of generating electrical energy while simultaneously dampening the vertical acceleration.
A regenerative suspension system that is adaptable to the road profile.
A regenerative suspension system that can effectively harness the energy otherwise wasted in the form of heat.
A regenerative suspension system that increases the overall efficiency of the vehicle especially during high speeds.
A regenerative suspension system that facilitate continuous generation of power when the vehicle is in a state of motion.
A regenerative suspension system that is cost effective and maintenance free.
A regenerative suspension system that does not require a magneto rheological fluid for varying the damping characteristics.
Certain modifications and improvements in the proposed invention will become readily apparent to a person of ordinary skill in the art. Such changes must be treated as equivalents to the elements of the present invention. Conceivable changes, modifications and improvements in the claimed" invention by the use of substitutes and alternatives in terms of material, method, manufacturing process, configuration, arrangement, duplication etc., will render them fall very well within the scope of the claimed invention.

WE CLAIM:
1. A regenerative suspension system for a vehicle adapted for damping vertical
acceleration generated during motion and capable of transforming linear
displacement to electrical energy comprising:
• a coil spring biasedly coupling a suspended portion of said vehicle to an unsuspended portion of said vehicle;
• a magneto-motive damping system arranged inside a housing axially coupled to said coil spring and having a linear generator for transforming said linear displacement to electrical energy and simultaneously damping said vertical acceleration;
• wherein a fluid damping system arranged inside said housing and configured to operate at or above a threshold vertical acceleration is operatively coupled to said magneto-motive damping system and having a regulator for varying fluid pressure within said fluid damping system as a function of vertical acceleration acting on said unsuspended portion of said vehicle.
2. The regenerative suspension system as claimed in claim 1, wherein said housing
comprises an upper chamber, a lower chamber and a lower mounting point
adjoining said lower chamber and located external to said housing.

3. The regenerative suspension system as claimed in claim 1, wherein said magneto-motive damping system and said fluid damping system are operatively coupled by means of a linearly displaceable piston arrangement extending longitudinally through said housing and having a free end coupled to said upper mounting point and another end carrying a perforated piston dividing said lower chamber into at least two compartments.
4. The regenerative suspension system as claimed in claim 1, wherein said linear generator is arranged inside said upper chamber and having a ferrous core formed by a plurality of spacers carrying a plurality of annular magnets stacked coaxially, said ferrous core axially mounted on said piston arrangement so as to allow linear displacement of said ferrous core relative to a solenoid thereby transforming said linear displacement to electrical energy and simultaneously damping said vertical acceleration.
5. The regenerative suspension system as claimed in claim 1, wherein said regulator further comprises a flow path fluidly connecting said at least two compartments in said lower chamber and a valve disposed to intercept said flow path.
6. The regenerative suspension system as claimed in claim 5, wherein said valve varies said fluid pressure in proportion to residual vertical acceleration above said threshold vertical acceleration generated during motion of said vehicle.

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7. The regenerative suspension system as claimed in claim 5, wherein said valve assumes an inoperative configuration when said vertical acceleration is below said threshold vertical acceleration.
8. The regenerative suspension system as claimed in claim 5, wherein said valve assumes an operative configuration when said vertical acceleration is equal to said threshold vertical acceleration.
9. The regenerative suspension system as claimed in claim 5, wherein said valve assumes a fully operative configuration when said vertical acceleration is above said threshold vertical acceleration.
10. The regenerative suspension system as claimed in claim 1, wherein said vertical acceleration is measured by means of an accelerometer positioned on said unsuspended portion of said vehicle.
11. The regenerative suspension system as claimed in claim 1, wherein said vertical acceleration is measured by means of an accelerometer positioned on said housing.
12. The regenerative suspension system as claimed in claims 5 and 10, wherein said valve is operated by means of a microcontroller receiving an input signal from said accelerometer.
13. The regenerative suspension system as claimed in claim 5, wherein said valve is a solenoid actuated check valve.

14. A self-propelled vehicle having a power source, at least a pair of ground engaging wheels with at least one of said ground engaging wheels propelled by means of a drive received from said power source wherein said vehicle having a regenerative suspension system as claimed in claim 1.