shock absorber

Abstract

Suspension strut (10) for a vehicle, the suspension strut (10) comprising: a first connector (12) for connecting to a first point on the vehicle; a second connector (18) for connecting to a second point on the vehicle; and a damper assembly (30) adapted to provide a damper force when fluid flows through the damper assembly (30) during relative compression between the first point and the second point, wherein the damper assembly (30) comprises a sidewall (310) and a damper opening (312) in the sidewall (310), the damper opening (312) being open during operation of the spring to allow fluid to flow through the damper assembly (30); the spring strut (10) further comprising: a piston (20); and a first chamber (22) on a first side of the piston (20), wherein a displacement of the first point relative to the second point is counteracted by a change in volume of the first chamber (22) due to a movement of the piston (20); wherein the piston (20) is a floating piston (20) and the strut (10) comprises a second chamber (24) on a second side of the piston (20); and wherein the piston (20) comprises a second cavity (204) on the second side of the piston (20), the second cavity (204) forming part of the second chamber (24); and wherein the damper assembly (30) further comprises a damper valve (302) that can be opened by the fluid flowing through the damper assembly (30) during relative compression between the first point and the second point, the damper valve (302) remaining closed while fluid flows through the damper assembly (30) during relative extension between the first point and the second point; and characterized in that the damper valve (302) comprises: a valve opening (306) provided in an axial surface of the damper assembly (30); a plate (304) configured to be disposed on the same axial surface of the damper assembly (30); and a pre-tensioning device (308), wherein the biasing device (308) biases the plate (304) toward the valve opening (306) and the axial surface to close the valve opening (306), and fluid flowing through the damper assembly (30) during relative compression between the first point and the second point causes the plate (304) to move away from the valve opening (306) and the axial surface to open the damper valve (302).

Description

[0001] The invention relates to a suspension strut and a vehicle.

[0002] Vehicle struts often include a damper device to provide a damping force that counteracts compression of the strut. However, it is desirable to avoid such a damping force during strut rebound, where a faster response time is desirable.

[0003] According to a first aspect of the invention, there is provided a suspension strut for a vehicle, the suspension strut comprising: a first fitting for connection to a first point on the vehicle; a second fitting for connection to a second point on the vehicle; and a damper assembly adapted to provide a damping force when fluid flows through the damper assembly during relative compression between the first point and the second point, the damper assembly comprising a sidewall and a damper opening in the sidewall, the damper opening being open during operation of the suspension strut to allow fluid to flow through the damper assembly.

[0004] Providing such a damper opening is advantageous because it allows for a reduction in damping during relative extension between the first point and the second point, resulting in a faster rebound response. The reduction in damping is less significant during relative compression, since relative compression occurs much faster than relative extension.

[0005] In one example, the damper assembly includes a damper valve that is openable by fluid flowing through the damper assembly during relative compression between the first point and the second point, wherein the damper valve remains closed when fluid flows through the damper assembly during relative expansion between the first point and the second point. In one example, the damper valve includes: a plate; a valve opening; and a biasing device, wherein the biasing device biases the plate toward the valve opening to close the valve opening, and fluid flowing through the damper assembly during relative compression between the first point and the second point causes the plate to move away from the valve opening to open the damper valve.The damper valve is particularly advantageous in combination with the damper port, as the fact that the port is located in a sidewall means that the entire axial area of the damper assembly can be used for the damper valve. This increases the surface area of the damper valve, making it easier to open with only a small differential pressure across the damper valve.

[0006] In one example, the strut further includes second and third damper openings in the sidewall of the damper assembly, wherein the second and third damper openings are open during operation of the strut to allow fluid to flow through the damper assembly.

[0007] In one example, the strut further comprises a rod connected to the first point; a cylinder connected to the second point, the cylinder movable relative to the rod to cause displacement of the first point relative to the second point; the damper assembly located within an end region of the rod, the damper assembly providing a damping force when fluid flows through the damper assembly into the rod during relative compression between the first point and the second point.

[0008] In one example, the strut further comprises a piston and a first chamber on a first side of the piston, wherein a displacement of the first point relative to the second point is counteracted by a volume change of the first chamber due to movement of the piston.

[0009] In one example, the piston includes a first cavity on the first side of the piston, the first cavity forming part of the first chamber. Providing the first cavity is advantageous because it increases the effective volume of the first chamber. This means that in the event of a pressure drop in the first chamber, the effect on the strut's performance and the likelihood of piston bottoming out are reduced.

[0010] Furthermore, the increase in effective volume means that during relative compression between the first and second points, the pressure rise in the first chamber is reduced. This means the maximum operating pressure of the strut is lower, thus reducing stresses in the strut. This also means that the piston's pre-charge pressure (i.e., the pressure in the first chamber before the vehicle is raised to its operating height) can be increased without a corresponding increase in the maximum operating pressure, allowing the vehicle to carry a heavier load.

[0011] In one example, the piston is a floating piston, and the strut includes a second chamber on a second side of the piston. In one example, the piston includes a second cavity on the second side of the piston, the second cavity forming part of the second chamber. The second cavity is advantageous because the damping assembly can be located in the second cavity during rebound of the strut.

[0012] In one example, the first chamber and the piston are located within the rod, and the second chamber is at least partially located within the second cylinder, the piston being movable within the rod to cause movement of the rod relative to the cylinder and displacement of the first point relative to the second point.

[0013] In one example, the first chamber includes a first port that allows a first fluid to enter the first chamber during a pre-fill phase, the first port being operable to be closed during use.

[0014] In one example, the second chamber includes a second port that allows a second fluid to flow into the second chamber during a vehicle preparation phase, the second port being operable to be closed during use.

[0015] In one example, the first fluid is a gas and the second fluid is a liquid such that the second chamber is operable to maintain a substantially constant volume during use.

[0016] According to a second aspect of the invention, a vehicle is provided comprising a suspension strut as described above.

[0017] In one example, the vehicle is a military vehicle for carrying a weapon.

[0018] For a better understanding of the invention, reference is made, by way of example only, to the accompanying figures, in which Fig. 1 shows a sectional view of a spring strut; Fig. Figure 2 shows a perspective view of a piston; Fig. 3 shows a perspective sectional view of the piston; Fig. 4 shows a perspective view of a damper assembly; Fig. Figure 5 shows a sectional view of the damper assembly; Fig. Figure 6 shows a first sectional view of the strut during operation; Fig. Figure 7 shows a second sectional view of the strut during operation; Fig. Figure 8 shows a third sectional view of the strut during operation; and Fig. 9 shows a fourth sectional view of the strut during operation.

[0019] Referring to Fig. 1 shows a sectional view of a strut 10. The strut 10 includes a first connector 12 for connecting to a first point on a vehicle (not shown) and a second connector 14 for connecting to a second point on the vehicle. The first connector 12 and the second connector 14 are located at opposite end portions of the strut 10.

[0020] The shock absorber 10 includes a rod 16 connected to the first connecting piece 12. The rod 16 is formed integrally with the first connecting piece 12. The shock absorber 10 includes a cylinder 18 connected to the second connecting piece 14. The cylinder 18 is formed integrally with the second connecting piece 14. The rod 16 and the cylinder 18 are coaxial, with the rod 16 located within the cylinder 18 and movable relative to it. The rod 16 and the cylinder 18 are elongated. The rod 16 and the cylinder 18 are hollow. The rod 16 and the cylinder 18 are made of titanium.

[0021] The strut 10 comprises a piston 20 (described below with reference to Fig. 2 and Fig. 3). The piston 20 is a floating piston. The piston 20 is located within the rod 16 and is movable relative to it. The piston 20 seals the rod 16, thereby creating a boundary between a first chamber 22 and a second chamber 24.

[0022] The first chamber 22 is located entirely within the rod 16. The second chamber 24 is located at least partially within the cylinder 18. The second chamber 24 is located partially within the rod 16. The volume of the second chamber 24 located in the rod 16 and the cylinder 18 varies during operation of the strut 10, as described below with reference to Fig. 6 to Fig. 9 described.

[0023] The strut 10 includes a first port 26 in fluid communication with the first chamber 22. The first port 26 is closable by a fill valve (not shown), which closes after prefilling, thus forming a seal. The strut includes a second port 28 in fluid communication with the second chamber 24. The second port 28 is closable by a valve (not shown).

[0024] The strut 10 includes a seal 32 that provides a seal between the rod 16 and the cylinder 18. The seal 32 is attached to the cylinder 18 and surrounds the rod 16 to prevent fluid from escaping from the strut 10 via the cylinder 18. The seal 32 remains in place on the cylinder 18 as the rod 16 slides relative to the cylinder 18. The seal 32 is a wiper. In addition to the seal 32, other seals (not shown) are provided on the rod 16 and / or the cylinder 18.

[0025] The strut 10 comprises a damper assembly 30 (described below with reference to Fig. 4 and Fig. 5). The damper assembly 30 is located within the rod 16 in an end region of the rod 16. The damper assembly 30 is fixed in position within the rod 16. The damper assembly spans the entire diameter of the rod.

[0026] Referring to Fig. 2 and Fig. 3, views of the piston 20 are shown. The piston 20 includes a first cavity 202 on a first side of the piston 20. The piston 20 includes a second cavity 204 on a second side of the piston 20.

[0027] As in Fig. As shown in Figure 1, the first cavity 202 is in fluid communication with the first chamber 22 and forms a part of it. The presence of the first cavity 202 increases the effective volume of the first chamber 22. Likewise, the second cavity 204 is in fluid communication with the second chamber 24 and forms a part of it. The presence of the second cavity 204 increases the effective volume of the second chamber 24.

[0028] The piston 20 includes rounded edges on the first side and the second side of the piston 20. This prevents damage to the rod 16 and the damper assembly 30, as described below with reference to Fig. 6 to 9. The first cavity 202 is dimensioned such that a desired spring characteristic curve is provided for the piston 20.

[0029] Referring to Fig. 4 and Fig. 5 shows views of the damper assembly 30. The damper assembly 30 includes a damper valve 302. The damper valve 302 includes a plate 304, a valve opening 306, and a biasing device 308 (i.e., a spring). The damper valve 302 includes six valve openings 306, each of which has a diameter of 9 mm.

[0030] The damper assembly 30 has a top cap construction such that the damper assembly 30 includes a sidewall 310. The sidewall 310 extends along the strut in a substantially axial direction. Furthermore, the sidewall 310 extends completely around a circumference of the damper assembly.

[0031] The plate 304 is located on an axial surface of the damper assembly 30. The plate 304 extends over a large part of the diameter of the rod 16. The valve opening 306 is also located on the axial surface of the damper assembly 30. The preloading device 308 preloads the plate 304 towards the valve opening 306 such that the plate 304 closes the valve opening 306.

[0032] The damper assembly 30 comprises three damper openings 312 (only one of which is in Fig. 4). The damper openings 312 are located in the sidewall 310. The damper openings 312 extend through the sidewall 310 in a substantially radial direction. The damper openings 312 establish a fluid connection between two sides of the damper assembly 30. This means that fluid can flow through the damper openings 312 between the rod 16 and the cylinder 18.

[0033] The operation of the spring strut 10 will now be explained with reference to Fig. 6 to Fig. 9. For reasons of clarity, many reference symbols have been Fig. 6 to Fig. 9 is omitted. However, it is understood that the spring strut 10 of Fig. 6 to Fig. 9 is the same spring strut 10 that is used in Fig. 1 is shown.

[0034] Referring to Fig. Figure 6 shows a sectional view of the shock absorber 10 in a pre-fill phase. During the pre-fill phase, the first port 12 is fixed relative to the second port 14. A compressor is used to introduce a first fluid (which is a gas) through the first port 26 into the first chamber 22. This causes the piston 20 to slide along the rod 16 until the piston 20 reaches the damper assembly 30 and can move no further. Additional first fluid is added until a desired pre-fill pressure is reached in the first chamber 22. The first port 26 is then closed and remains closed during use. The first fluid is nitrogen.

[0035] Referring to Fig. Figure 7 shows a sectional view of the strut 10 in a static nominal ride height position on a vehicle. After the pre-filling phase, the first connection piece 12 is attached to the first point on the vehicle, and the second connection piece 14 is attached to the second point on the vehicle. The first point is connected to a wheel of the vehicle, while the second point is connected to a body of the vehicle.

[0036] To achieve the nominal static ride height position, a second fluid (which is a liquid) is pumped through the second port 28 into the second chamber 24 until the desired vehicle height is reached. During this process, the piston 20 moves within the rod 16, reducing the volume of the first chamber 22 and compressing the first fluid. This causes compression of the strut, reducing a displacement of the first point relative to the second point. Once the desired ride height is reached, the second port 28 is closed and remains closed during use. The second fluid is an oil.

[0037] Referring to Fig. Figure 8 shows a sectional view of the strut 10 in a piston-bottomed position. When the wheel travels over a bump, the strut 10 is compressed, reducing the displacement of the first point relative to the second point, causing the piston 20 to move within the rod 16 and thus reducing the volume of the first chamber 22. The compressed first fluid in the first chamber counteracts the compression of the strut 10.

[0038] During compression of the strut 10, the volume of the second chamber 24 (containing the second fluid, a liquid) remains approximately constant. The second fluid flows from the cylinder 18 into the rod 16, causing the plate 304 to move away from the valve opening 306, overcoming the preload device. The second fluid then flows through the valve openings 306, providing a damping force to counteract the compression and the movement of the first point toward the second point.

[0039] In the Fig. 8, the shock absorber has experienced considerable compression (because, for example, the wheel has traveled over a large bump), so that the piston 20 has reached a bottoming-out position in which the piston 20 touches the end of the rod. In this position, the entire first chamber 22 is located within the first cavity 202 of the piston 20. This demonstrates an advantage of the first cavity 202, which is that when the piston 20 bottoms out, a certain volume remains available for the first fluid, which means that the maximum operating pressure in the shock absorber 10 is much lower than in a shock absorber without such a first cavity 202. In addition, the rounded edge on the first side of the piston 20 helps to avoid damage to the rod 16.

[0040] Referring to Fig. Figure 9 shows a sectional view of the spring strut 10 in a position in which it is fully rebounded. Such rebound can occur when the wheel rebounds when driving over a bump, even if the vehicle is not in contact with the ground.

[0041] During rebound of the strut 10, the displacement of the first point relative to the second point increases, causing the piston 20 to move within the rod 16 and thus increasing the volume of the first chamber 22. The pressure in the first chamber 22 decreases as the first fluid expands while the vehicle is not in contact with the ground, counteracting the rebound.

[0042] During rebound of the shock absorber 10, the volume of the second chamber 24 (containing the second fluid, a liquid) remains approximately constant. The second fluid flows from the rod 16 into the cylinder 18. However, since the second fluid flows in the same direction as the preload of the preload device 308, the plate 304 continues to bear against the valve opening 306, causing the valve opening 306 to remain closed. However, the second fluid flows through the damper openings 312.

[0043] In the Fig.In the position shown in Figure 9, the strut has experienced significant rebound (for example, due to rebound after the wheel has traveled over a large bump), so that the piston 20 has reached a fully extended position in which the piston 20 almost touches the damper assembly 30. In this position, the damper assembly 30 is located within the second cavity 204, thereby preventing collision between the damper assembly 30 and the piston 20.

[0044] Although some preferred embodiments have been shown and described, it will be apparent to those skilled in the art that various changes and modifications may be made without departing from the scope of the invention as defined in the appended claims.

[0045] Attention is drawn to all documents and materials filed concurrently with or prior to this description in connection with this application and available for public inspection together with this description, and the contents of all such documents and materials are incorporated herein by reference.

[0046] All features disclosed in this description (including all appended claims, the abstract and the drawings) and / or all steps of a method or process disclosed therein may be combined with each other in any combination, except for combinations in which at least some of these features and / or steps are mutually exclusive.

[0047] Unless expressly stated otherwise, any feature disclosed in this description (including all appended claims, the abstract, and the drawings) may be replaced by alternative features serving the same, equivalent, or similar purpose. Thus, unless expressly stated otherwise, each disclosed feature is merely one example of a general range of equivalent or similar features.

[0048] The invention is not limited to the details of the above embodiment(s). The invention extends to all novel features or novel combinations of features disclosed in this description (including all appended claims, the abstract, and the drawings), or to all novel steps or novel combinations of steps of any method or process disclosed therein.

Claims

[1] Suspension strut (10) for a vehicle, the suspension strut (10) comprising: a first connector (12) for connecting to a first point on the vehicle; a second connector (18) for connecting to a second point on the vehicle; and a damper assembly (30) adapted to provide a damper force when fluid flows through the damper assembly (30) during relative compression between the first point and the second point, wherein the damper assembly (30) comprises a sidewall (310) and a damper opening (312) in the sidewall (310), the damper opening (312) being open during operation of the spring to allow fluid to flow through the damper assembly (30); the spring strut (10) further comprising: a piston (20); and a first chamber (22) on a first side of the piston (20), wherein a displacement of the first point relative to the second point is counteracted by a change in volume of the first chamber (22) due to a movement of the piston (20); wherein the piston (20) is a floating piston (20) and the strut (10) comprises a second chamber (24) on a second side of the piston (20); and wherein the piston (20) comprises a second cavity (204) on the second side of the piston (20), the second cavity (204) forming part of the second chamber (24); and wherein the damper assembly (30) further comprises a damper valve (302) that can be opened by the fluid flowing through the damper assembly (30) during relative compression between the first point and the second point, the damper valve (302) remaining closed while fluid flows through the damper assembly (30) during relative extension between the first point and the second point; and characterized by that the damper valve (302) comprises: a valve opening (306) provided in an axial surface of the damper assembly (30); a plate (304) configured to be disposed on the same axial surface of the damper assembly (30); and a pre-tensioning device (308), wherein the biasing device (308) biases the plate (304) toward the valve opening (306) and the axial surface to close the valve opening (306), and fluid flowing through the damper assembly (30) during relative compression between the first point and the second point causes the plate (304) to move away from the valve opening (306) and the axial surface to open the damper valve (302). [2] The strut (10) of claim 1, further comprising second and third damper openings (312) in the sidewall (310) of the damper assembly (30), the second and third damper openings (312) being open during operation of the spring (10) to allow fluid to flow through the damper assembly (30). [3] Suspension strut (10) according to claim 1 or 2, further comprising a rod (16) connected to the first point; a cylinder (18) connected to the second point, the cylinder (18) being movable relative to the rod (16) to cause displacement of the first point relative to the second point; wherein the damper assembly (30) is located within an end region of the rod (16), the damper assembly (30) providing a damper force when fluid flows through the damper assembly (30) into the rod (16) during relative compression between the first point and the second point. [4] Suspension strut (10) according to one of the preceding claims, wherein the piston (20) comprises a first cavity (202) on the first side of the piston (20), the first cavity (202) forming part of the first chamber (22). [5] Suspension strut (10) according to claim 3 or 4, wherein the first chamber (22) and the piston (20) are arranged within the rod (16) and the second chamber (24) is at least partially located within the cylinder (18), the piston (20) being movable within the rod (16) to cause movement of the rod (16) relative to the cylinder (18) and displacement of the first point relative to the second point. [6] A strut (10) according to any preceding claim, wherein the first chamber (22) includes a first port (26) allowing a first fluid to enter the first chamber (22) during a pre-charge phase, the first port (26) being operable to be closed in use. [7] The strut (10) of claim 6, wherein the second chamber (24) includes a second port (28) allowing a second fluid to flow into the second chamber (24) during a vehicle preparation phase, the second port (28) being operable to be closed in use. [8] A strut (10) according to claim 7, wherein the first fluid is a gas and the second fluid is a liquid such that the second chamber (24) is operable to maintain a substantially constant volume in use. [9] Vehicle comprising a suspension strut (10) according to any one of the preceding claims. [10] A vehicle according to claim 9, wherein the vehicle is a military vehicle for carrying a weapon.

Images