Linear damping system with variable flow area depending on the piston's displacement within its damping chamber

Abstract

Variable damping coefficient piston damper, the piston damper being formed of: - A damper rod [50] translating along a hollow cylinder [71]; the rod [50] being partly hollow, receiving a guide rod [30]; - A piston assembly composed of a lower half-piston [20] and an upper half-piston [21] held together; the volume generated by the assembly of the half-pistons [20] and [21] allowing a puck [10] to be held in a flat support relative to the assembly [20] [21], characterized in that the half-pistons [20] and [21] and the puck [10] have openings and in that the rotation of the puck [10] relative to the rod [30] and relative to the assembly of the half-pistons is achieved via one or more trenches following a helical trajectory on the outer surface of the guide rod [30] and whose shape coincides with a material extrusion made on the puck [10]” Figure for the abstract: Figure 5

Description

Title of the invention: Linear damping system with variable flow area depending on the piston's displacement in its damping chamber

[0001] The present invention relates to a linear damper architecture involving a variation of the internal fluid flow area as a function of the position of the piston on its axis of movement.

[0002] Traditionally, the architecture of a linear damper (excluding the spring) involves a closed cylindrical volume of oil in which a piston / rod assembly moves longitudinally along the cylinder axis. This linear movement is made possible by the passage of the internal fluid from one chamber to the other via the elastic deformation of a flap (valve) located on either side of the piston. It should be noted that hydraulic opening systems of the ball-spring type are also considered here as valves that open via the elastic deformation of the spring. This elastic deformation of the valves is due to the pressure difference between the two chambers. Once the valves are fully open (at the end stop or elastic limit), the fluid passage area is constant, resulting in a constant damping coefficient c for a given damper architecture and fluid.A static damping coefficient specific to each type of shock absorber reduces their usage profile and necessitates the addition of a spring to obtain a complete damping system in the presence of vibration. Figure 2 illustrates this principle of opening a high-pressure chamber [Pi] to a low-pressure chamber [Pj] via the elastic deformation of a membrane. The relative circulation of fluid from one chamber to the other allows the rod / piston assembly to translate in a movement whose damping is proportional to this opening area.

[0003] Other damping systems rely on the magnetorheological properties of the fluid used to vary its physical properties by applying a magnetic field. This solution allows the oil's fluidity, and therefore the damping coefficient c, to be varied according to the intensity of the applied magnetic field. However, this solution requires the addition of complex electromagnetic equipment in addition to external control to best manage the damping coefficient according to the application. Here too, the addition of a spring is necessary to compensate for any positional phenomena during vibration.

[0004] Other damping systems have been designed to achieve variation in the flow area via the helical movement of a valve along the stem axis. This rotation, caused solely by the pressure difference acting on the mechanism, This allows the fluid to be exposed to a larger or smaller passage area, thus varying the damping of the rod / piston movement. The position of the piston in this type of mechanism does not affect the kinematics present [see patent CN110319142B - 2019 - Jiangsu University].

[0005] The present system allows a new approach enabling variation of the damping coefficient, independently of the pressure differential, and without any change in the rheological properties of the fluid used. This variation of the damping coefficient is caused by the variation of the fluid passage area from one chamber to the other solely according to the position of the piston on its axis of movement. This purely mechanical solution offers a new approach to the design of damping systems, enabling, but not limited to: - Reduce the dynamic contribution of the spring by increasing the resisting force of the cylinder as the piston moves in the chamber (see [Fig.8]). - Increase the versatility of use of the shock absorber depending on the type of puck

[10] used (cf. [Fig.6]). - To allow the piston to self-lock before it comes into geometric conflict with the damping cushions located on either side of the piston stroke.

[0006] The architecture consists of a rod

[50] that translates along a sealed cylinder

[71] and is connected at its end by a piston assembly

[20] -

[21] via a retainer

[202] . The other end of the cylinder

[71] is connected, via a sealed retainer

[61] , to a pivot joint

[60] . The other end of the cylinder

[71] is also closed by an assembly

[70] that seals the cylinder chamber and guides the rod

[50] in translation. This same rod

[50] is partially hollow to accommodate the element

[30] , which passes through the piston assembly

[20] -

[21] and then enters the rod

[50] without ever making contact with it.

[0007] Parts

[20] and

[21] are held together by means of threaded, sealed fixing screws

[41] associated with an O-ring seal

[42] . The sealing of the contact between the piston

[20] -

[21] and the cylinder

[71] is ensured by a seal

[40] acting as a piston ring. The volume created by the assembly of parts

[20] and

[21] accommodates a cylindrical puck

[10] connected to parts

[20] and

[21] via a flat support using elastic seals

[101] and

[102] . This puck

[10] is also connected to the guide rod

[30] via a helical linkage allowing the puck

[10] to rotate relative to the assembly

[20] -

[21] when the piston-pull-rod assembly translates relative to the guide

[30] .

[0008] The closed cylinder

[71] being filled with a fluid such as hydraulic oil, the only way for this fluid to pass from one chamber to another, and thus allow the translation of the rod-piston-paddle assembly (

[50] -

[20] -

[21] -

[10] ), is to allow the Fluid flow through the piston

[20] -

[21] is achieved via opening areas. To ensure that the fluid passes through the piston without creating internal hydraulic pressure zones, the elastic elements

[101] and

[102] , in addition to providing flat support between the vane

[10] and the piston, ensure the piston is sealed against external hydraulic pressures. These elastic elements

[101] and

[102] are held in a fixed position relative to the piston

[20] -

[21] by means of appropriate recesses formed by material extrusions inside the piston halves

[20] and

[21] . A cylinder seal

[43] completes the internal sealing of the assembly

[20] -

[21] .

[0009] The puck

[10] consists of a cylinder with a cylindrical extrusion at its center, associated with two guides, also in the form of extrusions, following a circular helical path. This same helical path is followed by two grooves present on the cylindrical part

[30] . This combination of paths allows the puck

[10] to rotate along the axis of

[30] thanks to the guidance generated by the helical joint

[30] -

[10] . Furthermore, the puck

[10] is perforated around its periphery by a series of ports (extrusion "through" a volume according to any geometry). These ports are in variable phase, with the same number and arrangement of ports on the half-pistons

[20] and

[21] .

[0010] The relative rotation of the puck

[10] , causing the helical guidance of

[30] with respect to the piston

[20] -

[21] , allows the openings on

[10] to coincide, to a greater or lesser extent, with the same types of openings on

[21] and

[20] . This variation in alignment between these openings allows direct action on the fluid passage area between the two chambers of the cylinder. Since this variation is caused by the rotation of

[10] with respect to

[30] , it is therefore possible to vary the opening width, and thus vary the damping coefficient solely according to the position of the assembly

[10] -

[20] -

[21] with respect to

[30] , and by extension, the fixed assembly of the damper (

[71] ,

[70] ,

[60] , etc.).

[0011] The relative rotation of

[10] with respect to

[20] -

[21] is controllable only if the assembly

[20] -

[21] is considered to be fixed in rotation with respect to

[30] , and by extension, with respect to the entire fixed body of the shock absorber. This ensures that element

[10] is the only element to rotate during its movement along the guide axis

[30] . In order to guarantee this suppression of rotational degrees of freedom of

[20] -

[21] on the translational axis, it is necessary that the entire equivalence class (201, 202, 50, 51, etc.) be fixed in rotation on its translational axis with respect to the body of the shock absorber. To achieve this, element

[51] must be fitted with a ball-and-ring joint to ensure the isostaticity of the system while guaranteeing nominal operation of the mechanism.

[0012] The rotational guidance of

[10] relative to

[20] -

[21] is achieved via a helical guide rod

[30] , this same rod, to allow a complete translation of the rod The shock absorber must be inserted into the piston

[20] -

[21] and then travel through a hollow volume located along the axis of the shock absorber rod

[50] . This allows the rod

[50] and the rest of its equivalence class to translate freely along its axis without encountering a geometric conflict with the element

[30] . This architecture implies a variable volume located within the hollow space of the element

[50] and closed by the end of the rod

[30] . Since all volumes are filled with oil, it is therefore necessary that the oil present in this volume not be compressed during the reduction of this volume via the translation of

[30] within

[50] (assuming that the helical joint

[30] -

[10] is completely sealed, this would amount to completely blocking the shock absorber in translation). It is therefore necessary to allow this oil to escape during the reduction of this volume. An architecture is proposed via an extrusion of material along the axis of the element

[30] to its base.A network of channels at the base of

[30] is then set up to evacuate, or draw in, the oil according to the volume variation induced by

[30] and

[50] . Note that these channels must be as wide as possible so that the friction of the fluid along these conduits does not promote any damping phenomenon. Description of the figures

[0013] [Fig.1] represents the kinematic diagram of the mechanism with its main links.

[0014] [Fig.2] represents the physical phenomenon traditionally used in the shock absorbers to allow the fluid to pass from a high-pressure chamber to a low-pressure chamber, namely the elastic deformation of one or more membranes.

[0015] [Fig.3] represents a cross-sectional view of an example design based on the kinematic diagram shown in figure [Fig.1] and presents the main elements of the mechanism (guide rod

[30] , piston

[20] -

[21] , damper rod

[50] , etc.).

[0016] [Fig.4] represents a detailed cross-sectional view of the design shown in [Fig.3] and showing the piston elements

[20] -

[21] , the puck

[10] , the sealing elements

[40] ,

[43] ,

[101] ,

[102] ,

[0017] [Fig.5] represents the same elements detailed in [Fig.4] but this time in isometric view.

[0018] [Fig.6] Example of puck opening geometry

[10] , including curves of variation of the passage area according to the rotation 0 of

[10] relative to the piston

[20] -

[21] .

[0019] [Fig.7] represents an exploded view of the design assembly based on the kinematic principle diagram presented in [Fig.1].

[0020] [Fig. 8] represents the different dynamic phenomena between a conventional damper with a constant coefficient c, and the new proposed dynamic illustrating (at constant speed) a resistance to forward motion as a function of a coefficient the damping itself is a function of the displacement (c'= c(x)). Note that these graphs are purely for illustrative purposes, and that the geometry of the puck's holes

[10] as well as the type of trajectory it follows along its axis of translation

[30] significantly influence the evolution of this resistance to forward motion as a function of displacement.

[0021] List of assembly parts: - 10: Puck - 101: Upper elastic joint between

[10] and

[20] - 102: Lower elastic joint between

[10] and

[20] - 20: Lower half-piston - 21: Upper half-piston - 201: Sealing joint between

[50] and

[20] - 202: Positioning retainer for

[50] relative to

[20] - 30: Helical puck guide assembly - 40: Sealing gasket between the piston and the cylinder - 41: Sealed threaded assembly screw - 42: O-ring associated with

[41] - 43: Cylinder seal associated with

[20] and

[21] - 50: Shock absorber rod - 51: Part associated with the annular ball joint connection of

[50] with the frame - 60: Shock absorber base with pivot link - 61: Alignment piece of

[30] with respect to the pivot axis at

[60] - 70: Top cover of the shock absorber - 71: Shock absorber cylinder body List of figures: - [Fig. 1]: Kinematic diagram - [Fig.2]: Illustration of a hydraulic opening via deformation of a membrane - [Fig. 3]: Cross-sectional view - Complete shock absorber - [Fig. 4]: Cross-sectional view - internal composition of the piston - [Fig. 5]: Partial sectional isometric view - internal piston composition +puck - [Fig. 6]: Exploded view - partial assembly - [Fig. 7]: Variation of the opening A, B or C as a function of the rotation angle 9 - [Fig.8]: Implication of the positional parameter in the variation of the resistance to forward motion F Method of implementing the mechanism

[0022] With reference to Figures 3, 4, 5 and 7, the shock absorber device comprises a shock absorber rod

[50] , a piston composed of two cups

[20] and

[21] held at

[500] via the assembly element

[202] . The element

[60] accommodates a pivot joint. The element

[51] accommodates a ball-and-ring joint. The assembly

[50] -

[20] -

[21] translates relative to the shock absorber body

[71] -

[70] -

[60] -

[61] .

[0023] The puck

[10] is held in a flat bearing position relative to the assembly

[20] -

[21] via the deformable elements (e.g., elastomer seal)

[101] and

[102] . The sealing of the cavity created by the assembly of the elements

[20] and

[21] is ensured by the installation of elastomer seals

[42] and

[43] as well as the use of assembly screws with a sealing thread.

[0024] The rotation of the puck

[10] relative to the guide axis

[30] is achieved by designing one or more grooves on the outer surface of

[30] and following a helical path along the axis of the cylinder

[30] . The shape of this groove must coincide with a material extrusion on the puck

[10] so that the puck can fit axially onto

[30] . Thus, the extrusions of

[10] are in place within the grooves of

[30] and allow complete guidance of

[10] as it translates along

[30] . Note that the helical guide path imposed by

[30] can be constant or variable as required.

[0025] All the elements shown in Figures 3, 4, 5, 6 and 7 can be made from materials traditionally used in the design of industrial shock absorbers (steel, aluminum, brass, bronze, etc.). Sealing techniques and elements traditionally used in the hydraulic field can be employed to ensure the necessary sealing of this mechanism.

Claims

Demands

1. A piston damper with a variable damping coefficient, the piston damper being formed of: - A damper rod [50] translating along a sealed cylinder [71], one end of which is closed by an upper damper cover [70] ensuring the sealing of the cylinder chamber as well as the translational guidance of the damper rod [50], and the other end by a sealed retainer [61] connected to a pivot joint [60]; the damper rod [50] being partially hollow and receiving a guide rod [30]; - A piston assembly composed of a lower half-piston [20] and an upper half-piston [21] held together by sealing threaded fixing screws [41]; the piston assembly being held to one end of the damper rod [50] via an assembly element [202];the volume generated by the assembly of the lower half-piston [20] and upper half-piston [21] allowing to accommodate a puck [10] held in plan support by the assembly [20] [21] via elastic joints [101] and [102] characterized in that the lower half-piston [20], the upper half-piston [21] and the puck [10] have openings and in that the rotation of the puck [10] with respect to the guide rod [30] and with respect to the upper half-piston [20] and lower half-piston [21] is carried out via one or more trenches following a helical trajectory on the outer surface of the guide rod [30] and whose shape coincides with an extrusion of material made on the puck [10];

2. Piston damper with variable damping coefficient according to claim 1 characterized in that the number and arrangement of the openings of the puck [10] are the same as those of the lower [20] and upper [21] half-piston.

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