SHOCK ABSORBER WITH FREQUENCY-DEPENDENT LOAD REGULATION BY HYDRAULIC INERTIA

Abstract

Hydraulic damper with load regulation as a function of frequency by means of hydraulic inertia composed of a cylinder, comprising an inner chamber, a rod, a main piston and an inertia piston, immersed in a hydraulic fluid, so that the inner chamber is divided into 3 sub-chambers, the main piston comprises a flow path controlled by valves to allow bidirectional flow of fluid between the sub-chambers and the inertia piston comprises a flow path called the inertia channel configured to allow fluid flow between sub-cameras at both sides of the inertia piston.

Claims

1-6. (canceled)

7. Shock absorber (1) with frequency-dependent load regulation by means of hydraulic inertia comprising a cylinder (2) with an inner chamber (7), a piston rod (3), a main piston (4) and an inertia piston (5); the main piston (4) is connected to the piston rod (3) and the inertia piston (5) is connected through at least one spring (11) to the piston rod (3), so that both pistons (4,5) move longitudinally in the cylinder (2); the main (4) and inertia (5) pistons are immersed in a hydraulic fluid (8), so that the inner chamber (7) is divided into a first sub-chamber (9), a second sub-chamber (10) and a third sub-chamber (10a), where said second sub-chamber (10) and said third sub-chamber (10a) are provided on both sides of the inertia piston (5); the main piston (4) comprises at least one conduit (6) configured to allow bi-directional flow of said hydraulic fluid (8) between said first sub-chamber (9) and said third sub-chamber (10a) controlled by valves (13) that allow regulating the passage of said hydraulic fluid (8) between said first sub-chamber (9) and said third sub-chamber (10a); the inertia piston (5) comprises at least one inertia channel conduit (12) configured to allow the flow of said hydraulic fluid (8) between said second sub-chamber (10) and said third sub-chamber (10a).

8. Shock absorber according to claim 1, comprising a conduit (14) within the piston rod (3).

9. Shock absorber according to claim 8, wherein said conduit (14) connects the first sub-chamber (9) and the second sub-chamber (10) to allow the flow of the hydraulic fluid (8) between the first sub-chamber (9) and the second sub-chamber (10), this flow being controlled by the movement of a slide valve (15) directly connected to the inertia piston (5).

10. Shock absorber according to claim 8, wherein said conduit (14) connects the first sub-chamber (9) and the third sub-chamber (10a) to allow the flow of the hydraulic fluid (8) between the first sub-chamber (9) and the second sub-chamber (10), this flow being controlled by the movement of a slide valve (15) directly connected to the inertia piston (5).

11. Shock absorber according to claim 8, wherein said conduit (14) connects the first sub-chamber (9) and the second sub-chamber (10) to allow the flow of the hydraulic fluid (8) between the first sub-chamber (9) and the second sub-chamber (10), this flow being controlled by the movement of a slide valve (15) connected to the inertia piston (5) through a second spring (17).

12. Shock absorber according to claim 8, wherein said conduit (14) connects the first sub-chamber (9) and the third sub-chamber (10a) to allow the flow of the hydraulic fluid (8) between the first sub-chamber (9) and the second sub-chamber (10), this flow being controlled by the movement of a slide valve (15) connected to the inertia piston (5) through a second spring (17).

13. Shock absorber according to claim 9, further comprising at least one valve (16) to regulate the flow through the conduit (14) in at least one direction.

14. Shock absorber according to claim 10, further comprising at least one valve (16) to regulate the flow through the conduit (14) in at least one direction.

15. Shock absorber according to claim 11, further comprising at least one valve (16) to regulate the flow through the conduit (14) in at least one direction.

16. Shock absorber according to claim 12, further comprising at least one valve (16) to regulate the flow through the conduit (14) in at least one direction.

Description

DESCRIPTIONS OF THE DRAWINGS

[0025] FIG. 1—Shows schematically a conventional damper design.

[0026] FIG. 2—Shows schematically an embodiment of a dynamic tuned mass damper according to this invention.

[0027] FIG. 3—Shows a more detailed 3D design of a dynamic tuned mass damper according to this invention.

PREFERRED EMBODIMENT OF THE INVENTION

[0028] Based on the design of a conventional shock absorber (20), in which a rod (3) is attached to a main piston (4) moving inside a hydraulic fluid (8) contained in a cylinder (2), calibrated holes (6) are created in the main piston (4) that enables the flow of fluid (8) from a first sub-chamber (9) to another second sub-chamber (10) or vice versa. The outer end of the rod (3), in the case of vehicles, is generally connected to the body of the vehicle and the cylinder (2) is connected to the wheel.

[0029] An additional piston (5) is introduced, inertia piston, that divides the chamber (10) into two sub-chambers (10) and (10a). In this way the fluid (8) contained in the shock absorber is divided into a first sub-chamber (9), a second sub-chamber (10) and a third sub-chamber (10a). The inertia piston (5) is connected by at least one first spring (11) to the rod (3). The second sub-chamber (10) and the third sub-chamber (10a) that are divided by the inertia piston (5) are connected by an inertia channel (12).

[0030] The pressure difference at both ends of the inertia channel (12) is proportional to the length of the inertia channel (12) and the mass flow through the inertia channel (12), inversely proportional to the cross-sectional area of the inertia channel (12). Because the total volume of the second sub-chamber (10) and the third sub-chamber (10a) is constant and considering that the fluid (8) is incompressible, the mass flow through the inertia piston (5) is proportional to the movement of the inertia piston (5) within the second sub-chamber (10) and the third sub-chamber (10a).

[0031] The movement of the inertia piston (5) equals to the movement of the rod (3) plus the relative movement of the inertia piston (5) with respect to the rod (3). Therefore, the frequency response of the inertia piston (3) is similar to the frequency response of a dynamic tuned mass damper. By appropriately choosing the parameters of the first spring (11) and the dimensions of the inertia channel (12), it is possible to adjust the resonance frequency of the inertia piston (5) and thus provide a dynamic damping of the wheel mass.

[0032] In an advanced embodiment of the idea presented here, a parallel fluid channel (14) is opened between the chambers (9) and (10) or (10a) separated by the main piston (4). This flow, hydraulically parallel to the main piston (4) is opened or closed by the inertia piston (5) or by a sliding valve (15) rigidly or elastically connected to the piston (5). The inertia piston (5) moves under movements of the main piston of high frequencies (4), whereby the inertia piston (5) or the sliding valve (15) opens an additional flow (14) only at high frequencies decreasing the pressure difference on both sides of the main piston (4) and therefore decreasing the viscous damping force.

[0033] In a more advanced design, high frequency flow can be controlled through a load regulating valve (16) so that the pressure difference at high frequencies can be controlled more precisely.