Hydraulic shock absorber with two electronically controlled valves, in particular for vehicle suspensions

Abstract

The hydraulic shock absorber (10) includes: a cylindrical body (12) comprising an inner cylindrical tube (16) and an outer cylindrical tube (18) defining a reservoir (20) for containing damping fluid; a piston (22) slidably mounted in the inner cylindrical tube (16) to divide the internal volume of the inner cylindrical tube into a rebound chamber (24) and a compression chamber (26); and a pair of electronically controlled valves (42, 44) configured to separate the rebound chamber (24) and the compression chamber (26) from the reservoir (20). The system includes: fluid communication; an auxiliary conduit (46) designed to bypass the storage chamber (20) to provide fluid communication between the compression chamber (26) and the second electronic control valve (44); and a valve assembly (48) mounted at the bottom of the inner cylindrical tube (16) and including at least a first channel (50) and a second channel (52), the first channel and the second channel being configured to provide fluid communication between the compression chamber (26) and the storage chamber (20) and to provide fluid communication between the compression chamber (26) and the auxiliary conduit (46), respectively.

Description

Technical Field

[0001] The present invention relates to a hydraulic shock absorber with variable damping as specified in the preamble of independent claim 1, and in particular to a hydraulic shock absorber designed for use in vehicle suspension. Background Technology

[0002] Variable damping hydraulic shock absorbers are known, which include two electronically controlled valves, which are implemented, for example, as solenoid valves.

[0003] In this solution, the first valve is designed to regulate the flow of damping fluid in the shock absorber only during the compression phase, while the other valve is designed to regulate the flow of damping fluid only during the rebound phase.

[0004] This type of shock absorber is known, for example, from DE 10 2005 053 394 A1.

[0005] According to these known solutions, the shock absorber includes: an outer cylindrical tube; an inner cylindrical tube coaxial with the outer cylindrical tube and defining a reservoir together with the outer cylindrical tube; a rod arranged coaxial with and partially projecting from the two cylindrical tubes; and a piston slidably mounted in the inner cylindrical tube and fixed to the lower end of the rod. The piston divides the internal volume of the inner cylindrical tube into a rebound chamber and a compression chamber, both of which contain damping fluid. The piston is equipped with a first valve assembly comprising a pair of one-way valves, specifically a compensation valve and a rebound valve, the compensation valve regulating the flow of damping fluid from the compression chamber to the rebound chamber during the compression phase, and the rebound valve regulating the flow of damping fluid from the rebound chamber to the compression chamber during the rebound phase. A second valve assembly is installed at the bottom of the inner cylindrical tube. The second valve assembly includes a pair of check valves, namely a compression valve and a feed valve. The compression valve regulates the flow of damping fluid from the compression chamber to the storage chamber during the compression phase, and the feed valve regulates the flow of damping fluid from the storage chamber to the compression chamber during the rebound phase. The check valves in these two valve assemblies are implemented as passive valves.

[0006] Shock absorbers known from DE 10 2005 053 394 A1 also include a first electronic control valve and a second electronic control valve, which are designed to regulate the flow of damping fluid during the rebound phase and the compression phase, respectively. More specifically, the first electronic control valve is connected on one side to a reservoir chamber and on the other side to a first intermediate chamber defined between an inner cylindrical tube and a first intermediate cylindrical tube, the first intermediate cylindrical tube being radially inserted between the inner and outer cylindrical tubes, the first intermediate chamber being in permanent fluid communication with the rebound chamber. The first electronic control valve is designed to regulate the flow of damping fluid from the rebound chamber through the first intermediate chamber to the reservoir chamber during the rebound phase, and thereby regulate the damping force of the shock absorber during this phase. The second electronic control valve is connected on one side to the reservoir chamber and on the other side to a second intermediate chamber defined between an inner cylindrical tube and a second intermediate cylindrical tube, the second intermediate cylindrical tube being radially inserted between the inner and outer cylindrical tubes, the second intermediate chamber being in permanent fluid communication with the compression chamber. The second electronic control valve is designed to regulate the flow of damping fluid from the compression chamber through the second intermediate chamber to the storage chamber during the compression phase, and thereby regulate the damping force of the shock absorber during this phase.

[0007] The valve bodies of the two electronically controlled valves in this known shock absorber are positioned axially offset outside the outer cylindrical tube. Therefore, the shock absorber has a shape that is difficult to install in a vehicle, especially when available space is limited or a symmetrical cross-section is required. Summary of the Invention

[0008] The object of this invention is to provide a variable damping hydraulic shock absorber that provides an improved architecture while maintaining the advantages of using two electronically controlled valves in terms of damping characteristic adjustment range and efficiency.

[0009] According to the invention, this and other objectives are achieved by a variable damping hydraulic shock absorber having the features defined in the appended independent claim 1.

[0010] Advantageous embodiments of the invention are specified in the dependent claims, the contents of which are considered part of the following description.

[0011] Essentially, the present invention is based on the idea of ​​equipping a hydraulic shock absorber with a bypass conduit formed in the end section of the outer tube and designed to connect the compression chamber to an electronically controlled valve via a valve assembly, which preferably includes a wave spring.

[0012] Furthermore, thanks to the above solutions, the shock absorber can be easily constructed so that the electronic valve is coaxial, which makes the shape of the shock absorber symmetrical, thus facilitating its installation on the vehicle. Attached Figure Description

[0013] Other features and advantages of the invention will become clearer from the following detailed description, provided purely by way of non-limiting example with reference to the accompanying drawings, in which:

[0014] - Figure 1 This is a schematic cross-sectional view of a hydraulic shock absorber during the rebound phase according to an embodiment of the present invention;

[0015] - Figure 2 Is in Figure 1 An enlarged view of the end section of the shock absorber configuration shown;

[0016] - Figure 3 During the compression phase Figure 1 A schematic axial cross-sectional view of the hydraulic shock absorber in the diagram; and

[0017] - Figure 4 Is in Figure 3 An enlarged view of the end section of the shock absorber configuration shown. Detailed Implementation

[0018] Before explaining the various embodiments of the present invention in detail, it should be understood that the invention is not limited in its application to the construction details and component configurations disclosed in the following description or illustrated in the drawings. The invention can be implemented in other ways and can be practiced or carried out in various manner. It should also be understood that the wording and terminology are descriptive in nature and should not be construed as limiting.

[0019] Reference Figure 1 In particular, hydraulic shock absorbers with variable damping designed for use in vehicle suspensions (hereinafter referred to as "shock absorbers") are generally represented by 10.

[0020] The shock absorber 10 includes: a cylindrical body 12 (hereinafter simply referred to as the "body") extending along a longitudinal axis x; and a rod 14 that partially protrudes from the body 12 (protruding upward from the viewer's perspective in the accompanying drawings) and is axially movable relative to the body 12 (i.e., movable in the direction of the longitudinal axis x).

[0021] The body 12 includes an inner cylindrical tube 16 and an outer cylindrical tube 18, which are arranged coaxially with each other and define a storage chamber 20 containing a damping fluid (typically oil, which will be simply referred to as oil below).

[0022] The piston 22 is slidably mounted inside the inner cylindrical tube 16 and fixed to the lower end of the rod 14. The piston 22 divides the internal volume of the inner cylindrical tube 16 into a spring chamber 24 and a compression chamber 26, both of which contain damping fluid (preferably oil).

[0023] The piston 22 may be configured to have a first valve assembly, which includes a pair of one-way valves, and more specifically a compensation valve and a spring valve, wherein the compensation valve allows oil to flow only in the direction from the compression chamber 26 to the spring chamber 24, and the spring valve allows oil to flow only in the direction from the spring chamber 24 to the compression chamber 26.

[0024] A first intermediate cylindrical tube 36 is arranged around and coaxially with the inner cylindrical tube 16. The first intermediate cylindrical tube 36 and the inner cylindrical tube 16 together define a first intermediate chamber 38, which is in fluid communication only with the rebound chamber 24.

[0025] Furthermore, a first electronic control valve 42 (hereinafter referred to as an electronic valve) is configured to fluidly communicate the first intermediate chamber 38 and the storage chamber 20 and to control the flow of damping fluid between the two chambers, and a second electronic control valve 44 is configured to fluidly communicate the compression chamber 26 and the storage chamber 20 and to control the flow of damping fluid from one to the other. The two electronic valves 42, 44 are arranged to project radially outward from the outer cylindrical tube 18 and are preferably supported by the outer cylindrical tube 18.

[0026] There is also an auxiliary pipe 46, which is designed to bypass the storage chamber 20 and fluidly connect the compression chamber 26 and the second electronic control valve 44.

[0027] A valve assembly 48 is also installed at the bottom of the inner cylindrical tube 16. The valve assembly 48 includes at least a first channel 50 and a second channel 52. The first channel 50 is designed to allow the compression chamber 26 to be in fluid communication with the storage chamber 20, and the second channel 52 is designed to allow the compression chamber 26 to be in fluid communication with the auxiliary pipe 46.

[0028] The valve assembly 48 includes at least one valve 54 configured to allow a certain flow rate of damping fluid from the storage chamber 20 through the first channel 50 to the compression chamber 26 when the shock absorber 10 is in the rebound (extended) state (while preventing fluid communication between the compression chamber 26 and the auxiliary pipe 46 through the second channel 52), and at least one valve 54 configured to allow a certain flow rate of damping fluid from the compression chamber 26 through the second channel 52 to the auxiliary pipe 46 when the shock absorber 10 is in the compressed state (while preventing fluid communication between the storage chamber 20 and the compression chamber 26 through the first channel 50).

[0029] The valve assembly 48, with one or more check valves associated with the corresponding channels 50, 52, is preferably implemented as passive valves.

[0030] According to a preferred embodiment, at least one valve 54 of the valve assembly 48 includes a wave spring. The spring is typically formed of wave-shaped washers that are angularly offset from each other and axially stacked such that the valley of one washer aligns with the peak of the washer below it.

[0031] According to a preferred embodiment, the auxiliary conduit 46 is at least partially disposed in the radial thickness of the end section 19 of the outer cylindrical tube 18 opposite to the side of the shock absorber body 12 with the protruding rod 14.

[0032] The end section 19 of the outer cylindrical tube 18, opposite to the side of the shock absorber body 12 with the protruding rod 14, can be constructed as a cap that fits onto the end of the outer cylindrical tube 18 to define the storage chamber 20 together with the inner cylindrical tube 16.

[0033] The end section 19 of the outer cylindrical tube 18 can protrude radially outward from at least a portion of the remaining outer cylindrical tube 18.

[0034] According to a preferred embodiment, the first electronic control valve 42 and the second electronic control valve 44 are arranged coaxially with each other.

[0035] The shock absorber 10 may include a second intermediate cylindrical tube 39 axially connected to a first intermediate cylindrical tube 36 and arranged coaxially with an inner cylindrical tube 16 to define a second intermediate chamber 40 together with the inner cylindrical tube 16. The second intermediate chamber 40 is in fluid communication with a rebound chamber 24 and / or a storage chamber 20 and can be arranged in fluid communication with a first intermediate chamber 38.

[0036] According to a preferred embodiment, a one-way valve 41 is arranged between the first intermediate chamber 38 and the second intermediate chamber 40. The one-way valve 41 is designed to allow fluid to pass from the second intermediate chamber 40 to the first intermediate chamber 38 when the shock absorber 10 is in a rebound state. The one-way valve 41 may be constructed, for example, as a deformable seal or a wave spring.

[0037] According to a preferred embodiment, the first electronic control valve 42 is connected to the first intermediate chamber 38 via its first passage and to the storage chamber 20 via its second passage, so as to selectively prevent or allow fluid to flow between the passages of the first electronic control valve 42.

[0038] According to a preferred embodiment, the second electronic control valve 44 is connected to the auxiliary conduit 46 via its first passage and to the storage chamber 20 via its second passage (e.g., via one or more openings 37 provided in the end section 19 of the outer cylindrical tube 18) in order to selectively prevent or allow fluid to flow between the passages of the second electronic control valve 44.

[0039] According to one embodiment of the present invention, the shock absorber 10 operates as follows.

[0040] During the rebound phase (extension) of the shock absorber 10, such as Figure 1 As illustrated, oil flows from the rebound chamber 24 (preferably via the second intermediate chamber 40) to the first intermediate chamber 38, and then from the first intermediate chamber 38 to the storage chamber 20 via the first electronically controlled valve 42. Fluid then flows from the storage chamber 20 into the compression chamber 26 through the first passage 50 of the valve assembly 48. According to one embodiment, the pressure difference between the storage chamber 20 and the compression chamber 26 causes the wave spring 54 to compress axially, thereby opening the first passage 50 and closing the second passage 52, thus preventing fluid communication between the compression chamber 26 and the auxiliary conduit 46 (preventing the second electronically controlled valve 44 from being supplied).

[0041] By properly guiding the first electronic control valve 42, the flow of oil from the springback chamber 26 to the storage chamber 20 can be regulated, thereby adjusting the damping force applied to the rod 14 during the extension phase.

[0042] During the compression phase of the shock absorber 10, such as Figure 3 As illustrated, valve assembly 48 is configured to close the first passage 50, thereby preventing fluid communication between the compression chamber 26 and the storage chamber 20, while opening the second passage 52, thereby fluidly communicating the compression chamber 26 and the second electronically controlled valve 44 through the auxiliary conduit 46 (e.g., the axial expansion of the spring 54 caused by the greater pressure exerted on the possible wave spring 54 by the fluid contained in the compression chamber 26 compared to the pressure of the fluid in the storage chamber 20, causing the spring 54 to close the first passage 50 and open the second passage 52).

[0043] By properly guiding the second electronic control valve 44, the flow of oil from the compression chamber 26 to the storage chamber 20 can be regulated, and thus the damping force applied to the rod 14 during the compression phase can be regulated.

[0044] According to the present invention, a hydraulic shock absorber with variable damping has been described.

[0045] Of course, the embodiments and details thereof may be modified relative to those described and illustrated purely by way of non-limiting example without departing from the principles of the invention, and without departing from the scope of the invention as defined in the appended claims.

Claims

1. A hydraulic shock absorber (10) having variable damping, particularly for use in vehicle suspension, the hydraulic shock absorber (10) comprising: A cylindrical body (12) and a rod (14) are provided, the cylindrical body (12) extending along a longitudinal axis (x), the rod (14) protruding partially from the body (12) and being axially movable relative to the cylindrical body (12), the cylindrical body (12) including an inner cylindrical tube (16) and an outer cylindrical tube (18) arranged coaxially with respect to each other and defining a storage chamber (20) containing damping fluid. A piston (22) is slidably mounted in the inner cylindrical tube (16) and fixed to the lower end of the piston rod (14). The piston (22) is configured to divide the internal volume of the inner cylindrical tube (16) into a spring chamber (24) and a compression chamber (26), both of which contain the damping fluid. A first intermediate cylindrical tube (36) is arranged around the inner cylindrical tube (16) and is coaxial with the inner cylindrical tube (16). The first intermediate cylindrical tube (36) and the inner cylindrical tube (16) together define a first intermediate chamber (38). The first intermediate chamber (38) is in fluid communication only with the springback chamber (24). A first electronic control valve (42) is arranged to protrude radially outward from the outer cylindrical tube (18) and is configured to fluidly communicate the first intermediate chamber (38) with the storage chamber (20) and control the flow of the damping fluid from one to the other; A second electronic control valve (44) is arranged to protrude radially outward from the outer cylindrical tube (18) and is configured to fluidly communicate the compression chamber (26) with the storage chamber (20) and control the flow of the damping fluid from one to the other; An auxiliary pipe (46) is provided, which is designed to bypass the storage chamber (20) and connect the compression chamber (26) to the second electronic control valve (44); and A valve assembly (48) is installed at the bottom of the inner cylindrical tube (16). The valve assembly (48) includes at least a first channel (50) and a second channel (52). The first channel (50) is designed to allow fluid communication between the compression chamber (26) and the storage chamber (20). The second channel (52) is adapted to allow fluid communication between the compression chamber (26) and the auxiliary pipe (46). The valve assembly (48) includes at least one valve (54). The at least one valve (54) is configured to allow a certain flow rate of the damping fluid when the shock absorber (10) is in the rebound state. The damping fluid flows from the storage chamber (20) through the first channel (50) to the compression chamber (26), preventing fluid communication between the compression chamber (26) and the auxiliary pipe (46) through the second channel (52), and the at least one valve (54) is configured to allow a certain flow rate of the damping fluid from the compression chamber (26) through the second channel (52) to the auxiliary pipe (46) when the shock absorber (10) is in a rebound state, preventing fluid communication between the storage chamber (20) and the compression chamber (26) through the first channel (50).

2. The shock absorber according to claim 1, wherein, The auxiliary pipe (46) is at least partially formed in the radial thickness of the end section (19) of the outer cylindrical tube (18) opposite to the side of the body (12) of the shock absorber that protrudes from the rod (14).

3. The shock absorber according to claim 1 or 2, wherein, The end section (19) of the outer cylindrical tube (18), opposite to the side of the body (12) of the shock absorber that protrudes from the rod (14), is constructed as a plug, which is fitted onto the end of the outer cylindrical tube (18) to define the storage chamber (20) together with the inner cylindrical tube (16).

4. The shock absorber according to any one of the preceding claims, wherein, The end section (19) of the outer cylindrical tube (18) protrudes radially outward from at least a portion of the remaining outer cylindrical tube (18).

5. The shock absorber according to any one of the preceding claims, wherein, The first electronic control valve (42) and the second electronic control valve (44) are arranged coaxially with each other.

6. The shock absorber according to any one of the preceding claims, wherein, The at least one valve (54) of the valve assembly (48) includes a wave spring.

7. The shock absorber according to any one of the preceding claims, wherein, The shock absorber (10) includes a second intermediate cylindrical tube (39) which is axially connected to the first intermediate cylindrical tube (36) and arranged around the inner cylindrical tube (16) coaxially with the inner cylindrical tube (16), thereby defining a second intermediate chamber (40) together with the inner cylindrical tube (16). The second intermediate chamber (40) is in fluid communication with the rebound chamber (24) and / or the storage chamber (20), and is adapted to be in fluid communication with the first intermediate chamber (38).

8. The shock absorber according to claim 7, wherein, A one-way valve (41) is inserted between the first intermediate chamber (36) and the second intermediate chamber (40). When the shock absorber (10) is in the rebound state, the one-way valve (41) is adapted to allow fluid to pass from the second intermediate chamber (40) to the first intermediate chamber (38).

9. The shock absorber according to any one of the preceding claims, wherein, The first electronic valve (42) is connected to the first intermediate chamber (38) through a first passage of the first electronic valve (42) and to the storage chamber (20) through a second passage of the first electronic valve (42) so as to selectively prevent or allow fluid to pass between the passages of the first electronic valve (42).

10. The shock absorber according to any one of the preceding claims, wherein, The second electronic valve (44) is connected to the auxiliary pipe (46) through a first passage of the second electronic valve (44) and to the storage chamber (20) through a second passage of the second electronic valve (44) so ​​as to selectively prevent or allow fluid to pass between the passages of the second electronic valve (44).

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