Step response damper

Abstract

A piston-and-cylinder type damper operable to perform a compression stroke and a return stroke includes a casing containing a damping fluid, an O-ring within the casing, and a piston assembly having a contact surface facing the O-ring. During a compression stroke, when the compression speed or force of the piston assembly is relatively low, the O-ring is disposed relative to the piston assembly in a first position defining first and second passageways for allowing damping fluid to flow from the first chamber to the second chamber, and when the compression speed or force of the piston assembly is relatively high, the O-ring is disposed relative to the piston assembly in a second position blocking the first passageway and allowing damping fluid to flow only through the second passageway. The first passageway is defined between the outer periphery of the piston assembly and the inner wall of the casing.

Description

[Technical field]

[0001] The present invention relates to a piston-cylinder type damper. [Background technology]

[0002] In many practical situations, it is necessary to provide a damper in which a piston in combination with a valve produces a variable damping force, i.e., a smaller force at lower closing speeds and a larger force at higher speeds of the compression stroke. Lower closing force means that less force is required to close the automatic closing mechanism of, for example, a sliding door, drawer, or cabinet door to which the damper is attached. It also relates to a lower opening force due to the spring. However, when the closing force or speed is high, it is desirable to have an increased damping response, for example to prevent damage to the mechanism and / or furniture parts.

[0003] In Patent Document 1 (EP2472140B1), Patent Document 2 (EP3480400A1), Patent Document 3 (EP3714184A1) and Patent Document 4 (WO2021 / 115515A1), a damper is provided in which the damping response is determined by a damping fluid flowing through a gap between the outer circumference of the piston assembly and the damper housing and a passage formed in the piston. When there is a high closing force, the disk deforms under pressure and closes the internal passage. This is disadvantageous because the definition of the final force when the closing force is high depends on the manufacturing tolerances of both the piston assembly and the housing. Furthermore, over time, wear and tear affects the malleability and deformability of the disk and the housing and the piston, causing the response definition of the mechanism to lose accuracy. This causes the damping force to change during the operating life of the damper, ultimately resulting in a lack of predictability and reliability before failure.

[0004] Therefore, there is a need in the art for new damper devices which eliminate or reduce such problems. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] EP2472140B1 [Patent Document 2] EP3480400A1 [Patent Document 3] EP3714184A1 [Patent Document 4] WO2021 / 115515A1 Summary of the Invention

[0006] A piston-cylinder type damper is disclosed herein. When high damping forces are required in response to a strong closing impulse, the damping force profile is determined solely by the geometry of the piston assembly and is independent of the housing. When designing and manufacturing a damper for high damping response, the design and possible degradation of the housing is not a consideration since the piston assembly is more easily designed, manufactured and more precisely controlled. It is also possible to model its behavior during its lifecycle with greater confidence.

[0007] According to one aspect of the present invention, 1. A piston-and-cylinder type damper operable to perform a compression stroke and a return stroke, comprising: a casing / cylinder containing a damping fluid; an O-ring within the casing; a piston assembly having a contact surface facing the O-ring; During the compression stroke: when the compression speed of the piston assembly or the force applied to the piston assembly is relatively low (below a certain threshold), the O-ring is disposed relative to the piston assembly in a first position defining a first passage and a second passage for damping fluid to flow from the first chamber to the second chamber; and when the compression speed of the piston assembly or the force applied to the piston assembly is relatively high (above the threshold value), the O-ring is disposed in a second position that blocks or seals the first passageway against the piston assembly and allows the damping fluid to flow only through the second passageway; the first passageway is defined about an outer periphery of the piston assembly, i.e., between said outer periphery and an inner wall / surface of the casing; A piston-cylinder type damper is disclosed.

[0008] Preferably, the O-ring is made of a flexible material and is deformable when in the second position and is non-deformable when in the first position.

[0009] Preferably, in the first position the O-ring is tilted at an angle relative to the contact surface, where the angle is defined as between the plane of the O-ring and the plane of the contact surface. Preferably, when the O-ring is in the first position, the angle is non-zero, and most preferably is between 2 and 8 degrees. Preferably, the plane of the O-ring and the plane of the contact surface are parallel when the O-ring is in the second position.

[0010] Preferably, the second passageway for conducting damping fluid from the first chamber to the second chamber is an internal passageway within the piston assembly, spaced apart from the periphery of the piston assembly but offset from the centre, and preferably has an opening in the contact surface at a location corresponding to the central bore of the O-ring (the second passageway opening into said bore in the O-ring).

[0011] Preferably, the contact surface of the piston assembly includes a protrusion, and when the compression speed or force of the piston assembly is relatively high above a threshold value, the O-ring is forced against the contact surface and deforms to surround the protrusion in the second position. Preferably, the contact surface of the piston assembly includes exactly one protrusion.

[0012] In one embodiment, the O-ring includes a protrusion facing the contact surface, and when the compression speed or force is relatively high, the O-ring is pressed against the contact surface while in the second position.

[0013] In one embodiment, the contact surface further comprises at least one groove and / or the O-ring comprises at least one groove facing the contact surface.

[0014] Preferably, the outer periphery of the O-ring is such that the O-ring is in contact with the inner wall of the casing at all times, so that damping fluid can only flow through the O-ring through its central bore during the compression or return stroke. Preferably, the O-ring has a diameter at least as large as the inner diameter of the casing.

[0015] In one embodiment, the compression speed or force of the piston assembly above which the O-ring blocks the first passageway and below which it does not block is a threshold defined by the bending stiffness of the O-ring and the shape or dimensions of the O-ring and / or protrusions.

[0016] According to one aspect of the present invention, A piston-and-cylinder type damper operable to perform a compression stroke and a return stroke, the damper comprising: a cylinder containing a damping fluid and having an inner wall; A flexible O-ring, a piston assembly having a contact surface including ribs facing the O-ring; an O-ring within the casing and a piston assembly having a contact surface facing the O-ring; the O-ring being operable, in response to a speed of a compression stroke, to flex about the rib to move between a first angle at which the O-ring seals a first damping fluid passage between a periphery of the piston assembly and an inner wall of the cylinder, and a second angle at which the O-ring leaves the first damping fluid passage open, the first and second angles being defined between a plane of the O-ring and a plane of a contact surface. is provided.

[0017] Preferably, the first angle is zero (0) and the second angle is between 2 and 8 degrees.

[0018] Preferably, a second damping fluid passage is provided defined internally only in the piston assembly, i.e., away from its outer periphery, and this second damping fluid passage is open to damping fluid when the O-ring is at the first angle and when the O-ring is at the second angle, i.e., regardless of the inclination of the O-ring relative to the piston assembly.

[0019] In order that the present invention may be more readily understood, various aspects of specific embodiments are described below in conjunction with the accompanying drawings. [Brief description of the drawings]

[0020] FIG. 1 shows a damper device according to one embodiment of the present invention. FIG. 2 is a close-up view of a portion of FIG. FIG. 3A is a close-up view of the damper with O-ring in a first configuration when the first flow path is accessible. FIG. 3B is a close-up view of the damper with O-ring in a second configuration when the first flow path is not accessible. 4A, 4B and 4C show portions of the piston assembly in different embodiments. 5A and 5B show different embodiments of an O-ring. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0021] Various aspects of the invention are described below.

[0022] Figure 1 shows a piston-cylinder type damper or damper assembly 100. A close-up or enlarged view of the circled area C is shown in cross section in Figure 2, and in three dimensions in Figures 3A and 3B in two different configurations. The damper has a housing or casing 110, which is typically cylindrical and has a (cylindrical) inner wall / surface 112. There is also a piston assembly 120, which has a piston rod 127 mounted for linear reciprocating movement relative to the casing 110 along a longitudinal axis X. Other standard features of piston-cylinder type damper devices are not described here.

[0023] The piston assembly 120 divides the interior of the cylinder 110 into two separate chambers, chamber A (compression chamber) and chamber B (reserve / overflow chamber), which are on the left and right sides, respectively, in FIG. 1. A sealing means 130 is provided to act as a seal for the housing 110 and is configured to movably engage an end section of the piston assembly 120 closest to chamber A. Specifically, the sealing means is configured to movably interact with the piston assembly 120 at its contact surface 122. The sealing means 130 is preferably an O-ring.

[0024] Preferably, the end section of piston assembly 120 includes a contact surface 122 facing chamber A and a stem 128 extending from contact surface 122 and terminating in an end cap 129. O-ring 130 has a central bore through which stem 128 passes and moves within the space between contact surface 122 and end cap 129, thereby limiting its freedom of longitudinal movement and angular tilt about axis X.

[0025] During a compression stroke of damper 100, in this case piston assembly 120 is forced inward (to the left in FIG. 1 ), causing damping fluid to flow from chamber A to chamber B through one or more passages defined by damper components, such as piston assembly 120, housing 110, and one or more of O-rings 130. During the return stroke of the damper, the piston assembly 120 moves in the opposite direction, outward (to the right in FIG. 1), causing damping fluid to flow from chamber B to chamber A. In this embodiment, assistance by a return means such as a spring on the side of chamber A during the return stroke of the damper may be provided, but is not considered.

[0026] The above-mentioned passageway or passageways are defined to control the flow of damping fluid when the damper is actuated, and are particularly important when the compression stroke is rapidly closing, resulting in a predictable damping response or profile. These passageways are described in more detail below.

[0027] The damping response is variable, or graduated, depending on the compression force experienced by the damper 100 / piston assembly 120. When the compression force / pressure is low (e.g., below a certain threshold force), the damping response is relatively small or zero; when it is high (at or above the threshold), the resulting damping force is high compared to the low compression mode. This can be done by reducing the number or total cross-sectional area of ​​the damping fluid passages going from chamber A to chamber B in the second scenario compared to the first scenario. By controlling the degree of restriction provided by the passages, the flow of fluid through the piston assembly 120 can be precisely tuned to achieve the desired damped resistance.

[0028] As mentioned above, in the fast compression, high damping mode, it is important that the damping force response is not linked to the design or condition of the housing 110. In other words, fluid must not flow through the passages between the housing inner wall 112 and the outer periphery 123 of the piston assembly 120. This allows for further improvement in accurate damping profile. Any such passages available in the low damping mode are sealed off in the high damping mode. This is made possible by arranging the piston assembly 120, O-ring 130 and housing 110 as follows:

[0029] At the contact surface 122 of the piston assembly 120, its cross-sectional shape has a smaller dimension than the inner circumferential wall 112 of the housing 110. This dimension is preferably only slightly smaller (although the diameter may be at most the same or substantially the same as the diameter of the housing). This shape is preferably not cylindrical. For example, the exact design may include recesses / notches / grooves, as most clearly shown in Figures 4A to 4C, which, when the piston is in place, define one or more channels between the housing 110 and the piston assembly 120 (at its outer periphery 123) to allow fluid to flow between chambers A and B (see also Figures 2, 3A, 3B). This forms part of a first flow path for damping fluid.

[0030] In the body of the piston assembly 120 itself, a channel or through hole 126 is formed, which is preferably an internal passage in the piston assembly 120 away from the outer periphery 123, as clearly shown in Figures 4A-4C. It connects chamber A and chamber B like a tunnel, and has a first opening on the side of chamber A on the contact surface 122 and a second opening on the other side (the side of chamber B), which serve as an inlet and an outlet, respectively, for the damping fluid during the compression stroke. It forms part of a second passage for the damping fluid. Alternatively, instead of one such through hole 126, multiple internal channels may be formed in the piston assembly to serve as a second passage between chamber A and chamber B.

[0031] The O-ring is configured to move between first and second configurations / positions relative to the piston assembly, as illustrated in Figures 3A and 3B, respectively. During a compression stroke, the piston assembly 120 moves along the longitudinal axis X toward the chamber A. This causes the contact surface 122 to be pushed toward the O-ring 130. When the compression stroke is strong (at high speeds), the O-ring 130 is in the second configuration (relative to the piston contact surface 122) and blocks the first passageway, thus only allowing fluid flow through the second passageway. When the compression stroke is weaker (low speed), below a certain threshold, O-ring 130 is in the first configuration (with respect to piston contact surface 122) and unblocks the first passageway, thus allowing fluid to pass from chamber A to chamber B via both the first and second passageways. This relative change in configuration / position of O-ring 130 implements a two-stage damping response during the compression stroke of damper 100.

[0032] In one aspect of the invention, when in the second configuration, O-ring 130 is in full or intimate contact with contact surface 122 of piston assembly 120 to the extent that fluid flowing through the bore of O-ring 130 cannot access the first passageway, i.e., the outer conduit defined between outer periphery 123 of piston assembly 120 and housing 110. This is shown in Figure 3B. The plane of O-ring 130 is preferably parallel to the plane of contact surface 122 and perpendicular to axis X.

[0033] In the first position of the O-ring 130, fluid can access the first passageway after passing through the holes in the O-ring, as shown in FIG. 3A and in cross section in FIG.

[0034] In one embodiment of the invention, the first and second configurations differ in the inclination angle of the O-ring 130. In this case, means are provided on the contact surface 122 of the piston assembly 120 for inclining the O-ring 124. These means can be projections 124 or ribs extending from the contact surface 122 towards the O-ring 130, as shown in FIG. 4A. If a sufficiently strong pressure is not applied during the compression stroke, the O-ring 130 is merely lightly pushed along inwards by the contact surface 122 including the projections 124, and this obstruction by the projections 124 means that the O-ring 130 is prevented from making a full contact with the contact surface 122.

[0035] However, in the fast compression mode, strong external forces on the piston 120 drive the contact surface 122 towards the O-ring 130 at such a speed or intensity that the O-ring deforms or flexes to encase the projection 124. Therefore, the O-ring 130 is both the sealing and the deforming part of the damper device 100. The O-ring is made of a sufficiently flexible or pliable material, such as rubber or other suitable plastic / polymeric material, that is elastically deformable and reversible. The O-ring is preferably of a standard design with a simple donut shape (not shown). In the deformed state, the O-ring makes full contact with the contact surface 122 of the piston 120 (as shown in FIG. 3B).

[0036] The means for tilting the O-ring is preferably a single protrusion 124 located on one side (not in the center of the contact surface 122) as shown in Figure 4A, but multiple protrusions are possible. This is a simple way to tilt the O-ring at an angle when the contact surface shape is asymmetric.

[0037] In a low damping mode where the compression force is below a certain threshold, the O-ring 130 either does not contact the forward facing end 122 of the piston assembly 120 at all or else contacts but does not intimately contact said contact surface and is unable to seal the outer periphery 123 of the piston 122 in the casing 100. This leaves a three-dimensional wedge-shaped gap between the contact surface of the piston assembly and the proximate surface of the O-ring, as shown in Figures 2 and 3A. In this way, the damping fluid in chamber A can access the channel between the outer side 123 of the flange of the piston assembly 120 and the inner surface 112 of the housing 110 through the central hole of the O-ring 130 to chamber B (i.e., the first passage). The damping fluid also enters the through hole 126, which does not seal because it opens into the "empty gap" where the hole of the O-ring 130 is, and the damping fluid exits on the other side of the piston 120 to chamber B (i.e., the second passage).

[0038] As the compressive force increases, eventually a threshold value is exceeded and the wedge-shaped gap closes up, sealing off the first passageway and leaving the second passageway as the only route for the damping fluid to travel from A to B. Thus, damping action increases rapidly.

[0039] It will be appreciated that the outer shape of the O-ring 130 is larger than the span or cross-sectional area of ​​the piston assembly 120, e.g., the outer shape of the O-ring is larger than the average diameter of the piston assembly 120 (which may or may not be cylindrical), and preferably larger than its maximum diameter.

[0040] The dimensions of O-ring 130 are preferably such that, even when tilted, its outer periphery will snugly fit against wall 112 of casing 110 so that fluid can always flow through the O-ring hole. Thus, the diameter of the O-ring is at least as large as the diameter of the interior space of the casing.

[0041] The dimensions of the projection 124 are preferably such that when the O-ring 130 is unforced (despite the compression stroke) and simply contacts the contact surface 122 of the piston assembly 120, tilted relative to the contact surface and undeformed (neglecting the projection, the contact surface is then generally parallel to the transverse plane of the housing 100 and perpendicular to the longitudinal axis X of the damper), the angle G formed between the plane of the tilted O-ring 130 and the contact surface 122 is equal to or greater than 2 degrees. This tilt angle G is preferably 8 degrees or less.

[0042] Different embodiments are possible to achieve the same goal.

[0043] For example, the contact surface 122 has one or more grooves 125 instead of (see FIG. 4B) or in addition to (see FIG. 4C) one or more protrusions. These grooves are blocked when the O-ring 130 and the contact surface 122 are compressed to (partially) deform the O-ring towards each other. In the case of embodiments without protrusions, the O-ring may not be in a tilted position before deformation.

[0044] As another example, the damper assembly 120 has no protrusions on the contact surface 122, but the O-ring 130 has one or more protrusions 132 (as shown in FIG. 5A) on its back side facing the contact surface 122 as a means of tilting and deforming under pressure. Any ribs 132 on the O-ring are not intended solely as a clearance means for returning flow during the return stroke. Alternatively, or in addition, the O-ring 130 can have one or more grooves 134 on its back side (as shown in FIG. 5B) that disappear when the O-ring and the contact surface compress toward each other.

[0045] Typically, corresponding projections or grooves are formed on either or both of the O-ring 130 and the piston contact surface 122 to bring them closer together or assist in providing a proper seal for the first passageway.

[0046] As mentioned above, O-ring 130 is not completely free to float in chamber A on one side of piston assembly 122, but is maintained adjacent to the contact surface by stem 128 which terminates in end cap 129. The dimensions (length and thickness) from the contact surface to the end cap can be selected to limit the longitudinal range of motion of the O-ring and the degree of tilt. For example, the maximum angle of tilt can be between 2 degrees and 8 degrees.

[0047] On the return stroke, the O-ring 130 moves out of engagement with the contact surface 122 of the piston assembly 120, thereby restoring the availability of both the first and second passages for damping fluid to flow from Chamber B to Chamber A.

[0048] In the above embodiment where the inclination of the O-ring 130 is variable, the threshold at which the compression force or velocity becomes large enough to close one of the passages between the two chambers is related to the inclination angle of the O-ring 130; the latter depends, for example, on the size and shape of the O-ring 130 and the protrusions 124 of the piston assembly 120. If the force increases during the compression stroke, the angle G decreases, and at some point the gap becomes small enough to block the first passage leaving only the second passage with damping. This means that it is relatively easy to reach that point by making the "default" inclination angle of the O-ring 130 smaller in the second position, such as by using a smaller protrusion 124 on the contact surface 122. That is, the compression force or velocity threshold is lower because the O-ring has to undergo less deformation to reach the second surface flat against the contact surface.

[0049] This force threshold is also related to the bending stiffness (i.e., degree of flexibility) of O-ring 130. Alternatively or additionally, in designing a damper, selecting a harder, less flexible material for the ring will result in a higher force and a faster rate at which O-ring 130 will deflect during the compression stroke, i.e., a higher threshold; selecting a softer, more flexible material means that the ring will require less deflection to change from tilting to full contact with contact surface 122, i.e., a lower threshold.

[0050] The damper device disclosed herein is intended to provide two different levels of damping on the compression stroke depending on the compression force / velocity of the piston, and is not intended to provide a modified passage between the compression stroke and the return stroke. The O-ring does not necessarily have to be in a flexed state for the entire compression stroke. During a single compression stroke, the O-ring does not necessarily have to be in a flexed state at all, and may be in a non-flexed state throughout.

[0051] The present invention is not limited to the above-described aspects and embodiments, and many variations are included within the scope of the claims. Various aspects and embodiments can be combined as necessary and appropriate. The figures are for illustrative purposes only, to facilitate understanding of the present invention.

Claims

1. 1. A piston-cylinder type damper operable to perform a compression stroke and a return stroke, comprising: a casing containing a damping fluid; an O-ring within the casing; a piston assembly having a contact surface facing the O-ring; During the compression stroke: when the compression speed or force of the piston assembly is relatively low, the O-ring is disposed relative to the piston assembly in a first position defining first and second passages for flowing damping fluid from the first chamber to the second chamber; and when the compression speed or force of the piston assembly is relatively high, the O-ring is disposed in a second position relative to the piston assembly to block the first passageway and permit the damping fluid to flow only through the second passageway; The first passage is defined between an outer periphery of the piston assembly and an inner wall of the casing. A piston-cylinder type damper characterized by:

2. 2. The damper of claim 1, wherein the O-ring is made of a flexible material that deforms when in the second position and does not deform when in the first position.

3. 3. A damper as claimed in claim 1 or claim 2, wherein the O-ring is inclined at an angle relative to the contact surface when in the first position.

4. 4. The damper of claim 3, wherein the angle is between 2 and 8 degrees.

5. 5. A damper as claimed in any one of claims 1 to 4, wherein when the O-ring is in the second position, the plane of the O-ring is parallel to the contact surface.

6. 6. A damper as claimed in any preceding claim, wherein the second passageway for passing damping fluid from the first chamber to the second chamber is an internal passageway in the piston assembly.

7. 7. The damper of claim 6, wherein the second passage has an opening on the contact surface at a location corresponding to the central hole of the O-ring.

8. 8. A damper as claimed in any one of claims 1 to 7, characterized in that the contact surface of the piston assembly includes a protrusion, and when the compression speed or force is relatively high the O-ring is pressed against the contact surface and deforms to wrap around the protrusion in the second position.

9. 9. The damper of claim 8, wherein the contact surface of the piston assembly includes exactly one protrusion.

10. 9. A damper as claimed in any one of claims 1 to 8, characterized in that the O-ring has a protrusion facing the contact surface, and when the compression speed or force is relatively high, the O-ring remains in the second position while receiving a force against the contact surface.

11. 11. A damper according to any one of claims 1 to 10, wherein the contact surface further comprises at least one groove and / or the O-ring comprises at least one groove facing the contact surface.

12. 12. A damper as claimed in any one of claims 1 to 11, characterized in that the outer periphery of the O-ring always snugs against the inner wall of the casing, such that during the compression stroke or return stroke damping fluid can only flow through the central opening of the O-ring.

13. 13. The damper of claim 12, wherein the O-ring has a diameter equal to or greater than the inside diameter of the casing.

14. 4. The damper of claim 3, wherein the compression speed or force threshold at which the O-ring blocks the first passageway is determined by the bending stiffness of the O-ring.

15. A piston-cylinder type damper operable to perform a compression stroke and a return stroke, the damper comprising: a cylinder containing a damping fluid and having an inner wall; A flexible O-ring; a piston assembly having a contact surface including ribs facing the O-ring; the O-ring is operable, in response to a speed of a compression stroke, to flex about the rib to move between a first angle at which the O-ring flexes and closes a first damping fluid passage between the periphery of the piston assembly and an inner wall of the cylinder, and a second angle at which the O-ring leaves the first damping fluid passage open, the first and second angles being defined between a face of the O-ring and a face of the contact surface.

16. 16. The damper of claim 15, wherein the first angle is zero (0) and the second angle is between 2 and 8 degrees.

17. 17. The damper of claim 15 or 16, further comprising a second damping fluid passage defined in the piston assembly, the second damping fluid passage being open to damping fluid when the O-ring is at the first angle and when the O-ring is at the second angle.

Images