Mr damper with asymmetric damping characteristics depending on the operating direction

Abstract

The present invention provides an MR damper having asymmetric damping characteristics according to the direction of operation, wherein the magnitude of the damping force is generated asymmetrically during compression and tension operations of the damper, thereby significantly enhancing ride comfort and driving stability. The MR damper comprises a cylinder and a valve assembly. The cylinder contains an MR fluid. The valve assembly is configured to be movable within the cylinder by an external force and includes a core body on which a coil is wound, a flux ring coupled to the core body in a manner that surrounds the core body, a main fluid passage formed between the core body and the flux ring through which the MR fluid passes, and an auxiliary fluid passage formed through which the MR fluid passes in an area not affected by an electromagnetic field generated in the main fluid passage. At this time, the auxiliary fluid passage has a first outlet through which the MR fluid flows in during compression operation and a second outlet through which the MR fluid flows in during tension operation, and the cross-sectional area of ​​the first outlet is larger than the cross-sectional area of ​​the second outlet.

Description

Technology Field

[0001] The present invention relates to an MR damper, and more specifically, to an MR damper for a vehicle that generates asymmetric damping force during compression and tension operations according to the operating direction of the damper. Background Technology

[0002] Magneto-rheological (MR) dampers generate an electromagnetic field through an applied current and can vary the damping force by changing the viscosity of the MR fluid, so they are widely used in vehicle suspension systems for ride comfort and driving stability.

[0003] The MR damper basically includes a cylinder that accommodates MR fluid and a valve assembly that is coupled to a piston rod and reciprocates within the cylinder. Additionally, the valve assembly includes a core body around which a coil is wound and a flux ring that is coupled to surround the outside of the core body to form a main fluid path through which the MR fluid passes.

[0004] In such an MR damper, when current is applied to the coil, an electromagnetic field is generated in the main flow path region, which increases the viscosity of the MR fluid passing through the main flow path and can generate a large flow resistance force during the process of passing through the main flow path. For example, if the piston rod undergoes compression and tension operations due to an external force applied from the outside, a large resistance force is generated in the MR fluid passing through the main flow path, which can generate a high damping force corresponding to the external force.

[0005] Meanwhile, to enhance passenger ride comfort and driving stability, automotive MR dampers require a damping coefficient that varies depending on the situation, rather than maintaining a constant value. For example, when crossing a speed bump, a relatively low damping coefficient is required during the process of the wheels entering the bump, while a relatively high damping coefficient is required during the process of the wheels exiting it. Furthermore, a relatively low damping coefficient is required during high-speed driving, and a relatively high damping coefficient is required during low-speed driving.

[0006] However, as explained above, while the required damping force range differs during tension and compression movements, the performance of MR dampers, which have symmetrical damping characteristics during tension and compression, has limitations in effectively ensuring satisfactory ride comfort and driving stability in various driving environments, such as acceleration and deceleration or driving over obstacles. Prior art literature

[0007] Republic of Korea Published Patent Application No. 2024-0071756 (Published May 23, 2024) The problem to be solved

[0008] The objective of the present invention to solve the aforementioned problems is to provide an MR damper having asymmetric damping characteristics according to the direction of operation, which can significantly improve ride comfort and driving stability by generating asymmetric damping force magnitudes during compression and tension operations of the damper.

[0009] The problems that the present invention aims to solve are not limited to those mentioned above, and other unmentioned problems will be clearly understood by those skilled in the art to which the present invention belongs from the description below. means of solving the problem

[0010] An MR damper having asymmetric damping characteristics according to the direction of operation according to an embodiment of the present invention for solving the above-mentioned problem comprises: a cylinder receiving an MR fluid; and a valve assembly having a core body that is configured to be movable inside the cylinder by an external force and on which a coil is wound, a flux ring coupled to the core body in a manner that surrounds the core body, a main flow path formed between the core body and the flux ring through which the MR fluid passes, and an auxiliary flow path formed through which the MR fluid passes in an area not affected by an electromagnetic field generated in the main flow path. In this case, the auxiliary flow path is characterized by having a first outlet through which the MR fluid flows during a compression operation and a second outlet through which the MR fluid flows during a tension operation, wherein the cross-sectional area of ​​the first outlet is larger than the cross-sectional area of ​​the second outlet.

[0011] In an MR damper having asymmetric damping characteristics according to the operating direction according to one embodiment of the present invention, the auxiliary flow path may be formed such that the cross-sectional area gradually decreases from the first outlet to the second outlet.

[0012] In an MR damper having asymmetric damping characteristics according to the operating direction according to one embodiment of the present invention, the auxiliary flow path may include a large diameter section extending while having the same cross-sectional area as the first outlet, a small diameter section extending while having the same cross-sectional area as the second outlet, and an inclined connecting section connecting the large diameter section and the small diameter section.

[0013] In an MR damper having asymmetric damping characteristics according to the operating direction according to one embodiment of the present invention, the auxiliary fluid path may be formed through the core body.

[0014] In an MR damper having asymmetric damping characteristics according to the operating direction according to one embodiment of the present invention, the auxiliary fluid path may be formed in a groove shape on the inner or outer surface of the flux ring.

[0015] In an MR damper having asymmetric damping characteristics according to the operating direction according to one embodiment of the present invention, the auxiliary fluid path may include a first auxiliary fluid path formed through the core body and a second auxiliary fluid path formed in a groove shape on the inner or outer surface of the flux ring. Effects of the invention

[0016] According to the present invention, by using an auxiliary fluid passage having an inlet and an outlet of different sizes through which an MR fluid passes, the magnitude of the damping force during compression and tension operations according to the direction of operation is asymmetrically generated, thereby significantly improving ride comfort and driving stability.

[0017] The effects of the present invention are not limited to the effects described above, and should be understood to include all effects that can be inferred from the configuration of the invention described in the detailed description or claims of the present invention. Brief explanation of the drawing

[0018] Figure 1 is a cross-sectional example diagram showing an MR damper without an auxiliary flow path. FIG. 2 is an example diagram illustrating the compression operation for first-direction operation and the tension operation for second-direction operation opposite to the first direction according to an MR damper without an auxiliary flow path. FIG. 3 is a cross-sectional example diagram showing an MR damper with an auxiliary flow path according to one embodiment of the present invention. FIG. 4 is an example diagram illustrating the compression action for first-direction operation and the tension action for second-direction operation opposite to the first direction according to an MR damper with an auxiliary flow path. Figure 5 is an example cross-sectional view showing an enlarged view of the auxiliary flow path of Figure 3. Figure 6 is an example diagram showing a comparison of the FV curve of Figure 2 and the FV curve of Figure 3. FIG. 7 is a cross-sectional example diagram showing an auxiliary flow path according to another embodiment of the present invention. FIG. 8 is an exemplary diagram showing an auxiliary flow path according to another embodiment of the present invention. Specific details for implementing the invention

[0019] The present invention will be described below with reference to the attached drawings. However, the present invention may be implemented in various different forms and is therefore not limited to the embodiments described herein. Furthermore, in order to clearly explain the present invention in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0020] Throughout the specification, when it is stated that a part is "connected (connected, in contact, combined)" with another part, this includes not only cases where they are "directly connected," but also cases where they are "indirectly connected" with other members interposed between them. Furthermore, when it is stated that a part "includes" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but rather allows for the inclusion of additional components.

[0021] The terms used herein are merely for describing specific embodiments and are not intended to limit the invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this specification, terms such as “comprising” or “having” are intended to indicate the presence of the features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, and should be understood as not precluding the existence or addition of one or more other features, numbers, steps, actions, components, parts, or combinations thereof.

[0022] Embodiments of the present invention will be described in detail below with reference to the attached drawings.

[0023] FIG. 1 is a cross-sectional example of an MR damper without an auxiliary flow path, and FIG. 2 is an example of explaining the compression operation for a first direction operation and the tension operation for a second direction operation opposite to the first direction according to the MR damper without an auxiliary flow path.

[0024] Referring to FIGS. 1 and 2, the MR damper includes a cylinder (10) and a valve assembly (20).

[0025] The cylinder (10) can accommodate MR fluid inside. The internal receiving space of the cylinder (10) in which the MR fluid is accommodated by the valve assembly (20) can be divided into a lower chamber and an upper chamber.

[0026] The valve assembly (20) can be coupled to the piston rod (21) and configured to be reciprocally movable inside the cylinder (10). When an external force applied from the outside is transmitted to the valve assembly (20) through the piston rod (21), the valve assembly (20) can be reciprocated inside the cylinder (10) to implement a damping operation.

[0027] The valve assembly (20) may have a core body (22), a flux ring (24), and a main flow path (25).

[0028] The core body (22) is coupled to the piston rod (21) and moves in conjunction, and a coil (23) can be wound around the outer surface. When current is applied from the outside, the coil (23) can generate an electromagnetic field around it.

[0029] The flux ring (24) can be attached to the core body (22) in a manner that wraps around the outer surface of the core body (22).

[0030] The main Euro (25) can be formed between the core body (22) and the flux ring (24) which are affected by the electromagnetic field generated from the coil (23).

[0031] When current is applied to the coil (23), an electromagnetic field is generated in the main flow path (25) region, and then the viscosity of the MR fluid passing through the main flow path (25) increases, and a large flow resistance force may be generated during the process of passing through the main flow path (25).

[0032] To elaborate, referring to the left side of FIG. 2, when an external force is applied to the valve assembly (20) in the first direction (D1), a compression operation can be implemented in which the valve assembly (20) moves downward in the drawing. During this compression operation, the MR fluid present in the lower chamber moves to the upper chamber by passing through the main passage (25). Since the MR fluid passing through the main passage (25) generates a flow resistance force due to the electromagnetic field, it generates an appropriate damping force against the external force applied in the first direction (D1), as shown in the F (damping force) - V (valve assembly velocity) diagram. For example, when an impact is transmitted as the wheel enters a speed bump while driving, the MR damper performs a compression operation, and during this compression process, the impact of entering the speed bump is absorbed, thereby increasing the ride comfort and driving stability of the vehicle.

[0033] And, referring to the right side of FIG. 2, when an external force is applied to the valve assembly (20) in a second direction (D2) opposite to the first direction (D1), a tensioning motion can be implemented in which the valve assembly (20) moves in the upward direction in the drawing. During this tensioning motion, the MR fluid present in the upper chamber moves to the lower chamber by passing through the main passage (25). Since the MR fluid passing through the main passage (25) generates a flow resistance force due to the electromagnetic field, it generates an appropriate damping force against the external force applied in the second direction (D2), as shown in the FV diagram. For example, when a shock is transmitted during the process of a wheel coming off a speed bump while driving, the MR damper undergoes a tensioning motion, and in this tensioning process, the shock of coming off the speed bump is absorbed, thereby increasing the ride comfort and driving stability of the vehicle.

[0034] Here, as shown in the FV diagram of FIG. 2, when external impacts in the first direction (D1) and the second direction (D2) are transmitted, such as when the vehicle is driving over obstacles or accelerating / decelering, damping forces of the same magnitude are generated during compression and tension operations acting on the MR damper. That is, the damping characteristics of the MR damper are symmetrically generated during compression and tension operations.

[0035] When the damping force of the MR damper is generated symmetrically during compression and tension operations, as explained above, a constant damping coefficient is maintained even when the driving conditions of the vehicle change, such as driving over obstacles or accelerating and decelerating, so further improvement in ride comfort and driving stability is required.

[0036] For example, when a vehicle goes over a speed bump, a relatively low damping coefficient is required during the process of the wheels entering the speed bump, and subsequently, a relatively high damping coefficient is required during the process of the wheels exiting the speed bump. That is, a soft ride is required due to a relatively low damping coefficient during the process of the MR damper compressing as the wheels enter the speed bump, and a hard ride is required due to a relatively high damping coefficient during the process of the MR damper tensing as the wheels exit the speed bump.

[0037] Ultimately, as the damping characteristics of the MR damper occurred symmetrically during compression and tension operations, there were limitations in improving ride comfort and driving stability.

[0038] To this end, the present invention is characterized by providing an MR damper capable of having asymmetric damping characteristics during compression and tension operations with respect to the operating direction of the damper. Accordingly, ride comfort and driving stability can be significantly improved even when the driving conditions of the vehicle change in various ways, such as driving over obstacles or driving with acceleration and deceleration.

[0039] FIG. 3 is a cross-sectional example showing an MR damper with an auxiliary fluid path according to the present invention, FIG. 4 is a cross-sectional example explaining a compression operation for a first direction operation and a tension operation for a second direction operation opposite to the first direction according to an MR damper with an auxiliary fluid path, FIG. 5 is a cross-sectional example showing an enlarged view of the auxiliary fluid path of FIG. 3, and FIG. 6 is a cross-sectional example showing a comparison of the FV curve of FIG. 2 and the FV curve of FIG. 3.

[0040] Referring to FIGS. 3 to 5, the valve assembly (20) according to the present embodiment further includes an auxiliary flow path (50).

[0041] The auxiliary channel (50) can be formed by penetrating the valve assembly (20) to allow MR fluid to pass through.

[0042] The auxiliary Euro (50) can be placed in an area that is not affected by the electromagnetic field generated in the main Euro (25).

[0043] A plurality of auxiliary passages (50) may be provided at regular intervals along the circumferential direction of the valve assembly (20), and a plurality of auxiliary passages may also be provided at regular intervals along the radial direction of the valve assembly (20).

[0044] The auxiliary flow path (50) may have a first outlet (50a) into which MR fluid flows during a compression operation corresponding to an external force acting in a first direction (D1), and a second outlet (50b) into which MR fluid flows during a tension operation corresponding to an external force acting in a second direction (D2) opposite to the first direction (D1).

[0045] In other words, during the compression operation of the MR damper, the MR fluid in the lower chamber flows into the first outlet (50a) and flows into the upper chamber through the second outlet (50b), and during the tension operation of the MR damper, the MR fluid in the upper chamber flows into the second outlet (50b) and flows into the lower chamber through the first outlet (50a). As shown in the drawing, the first outlet (50a) can be formed on the lower surface of the core body (22) of the valve assembly (20), and the second outlet (50b) can be formed on the upper surface of the core body (22) of the valve assembly (20).

[0046] Here, the first outlet (50a) may have a first cross-sectional area (A1) and the second outlet (50b) may have a second cross-sectional area (A2), and at this time, the first cross-sectional area (A1) may be formed larger than the second cross-sectional area (A2).

[0047] If the first cross-sectional area (A1) is larger than the second cross-sectional area (A2), when the MR fluid flows into the first outlet (50a) and is discharged through the second outlet (50b), it can generate a relatively smaller flow resistance force than when it flows into the second outlet (50b) in the opposite direction and is discharged through the first outlet (50a).

[0048] Referring to the left side of FIG. 4, when an external force is applied to the valve assembly (20) in the first direction (D1), a compression operation in which the valve assembly (20) moves downward in the drawing can be implemented. During this compression operation, the MR fluid present in the lower chamber passes through the main passage (25) and moves to the upper chamber. During this compression operation, an appropriate damping force can be generated by absorbing the external force applied in the first direction (D1).

[0049] At the same time, during compression operation, the MR fluid present in the lower chamber can move upward through the auxiliary channel (50). Since the MR fluid passing through the auxiliary channel (50) is placed in an area not affected by the electromagnetic field, only flow resistance due to Newtonian flow properties can be generated. According to this, if the cross-sectional area of ​​the main channel (25) and the auxiliary channel (50) is the same, the flow resistance of the MR fluid in the auxiliary channel (50) can be equal to the flow resistance of the main channel (25) from which the electromagnetic field has been removed, and the minimum flow resistance that can be generated in the main channel (25) when the electromagnetic field is generated can be generated.

[0050] Also, since the first cross-sectional area (A1) of the first outlet (50a) is formed to be larger than the second cross-sectional area (A2) of the second outlet (50b), a relatively small flow resistance force may be generated as the MR fluid in the lower chamber passes through the auxiliary flow path (50).

[0051] Ultimately, as shown in the FV diagram of FIG. 4, the combined flow resistance of the MR fluid passing through the main channel (25) and the auxiliary channel (50) together can generate a damping force of an appropriate size during the compression operation of the valve assembly (20).

[0052] For example, the FV compression curve formed by the combined flow resistance of the MR fluid passing through the main channel (25) and the auxiliary channel (50) together can significantly improve the ride comfort and driving stability required by the occupant by providing a soft ride due to a relatively low damping coefficient during the process of the wheels entering the speed bump when the vehicle goes over the speed bump.

[0053] Furthermore, referring to the right side of FIG. 4, when an external force is applied to the valve assembly (20) in the second direction (D2), a tensioning motion can be implemented in which the valve assembly (20) moves in the upward direction in the drawing. During this tensioning motion, the MR fluid present in the upper chamber passes through the main passage (25) and moves to the lower chamber. During this tensioning motion, the external force applied in the second direction (D2) is absorbed, and an appropriate damping force can be generated.

[0054] At the same time, during the tensioning operation, the MR fluid present in the upper chamber can move to the lower part by passing through the auxiliary fluid path (50). Since the MR fluid passing through the auxiliary fluid path (50) is placed in an area not affected by the electromagnetic field, only flow resistance due to Newtonian flow properties can be generated.

[0055] At this time, since the second cross-sectional area (A2) of the second outlet (50b) is formed to be smaller than the first cross-sectional area (A1) of the first outlet (50a), a relatively large flow resistance force may be generated as the MR fluid in the upper chamber passes through the auxiliary flow path (50).

[0056] Ultimately, as shown in the FV diagram of FIG. 4, the combined flow resistance of the MR fluid passing through the main channel (25) and the auxiliary channel (50) together can generate a damping force of an appropriate size during the tensioning operation of the valve assembly (20).

[0057] For example, the FV tension curve formed by the combined flow resistance of the MR fluid passing through the main channel (25) and the auxiliary channel (50) together can provide a hard ride due to a relatively high damping coefficient during the process of the wheels leaving the speed bump when the vehicle goes over the speed bump, thereby greatly improving the ride comfort and driving stability required by the occupant.

[0058] As a result, as shown in FIG. 6, by causing the damping force of the MR damper to be generated asymmetrically during the compression and tensioning process through the auxiliary flow path (50) having first and second outlets (50a) and (50b) of different sizes, it is possible to respond more effectively to various driving situations of the vehicle, such as driving over obstacles or driving with acceleration and deceleration, or various ride comfort requirements of the occupants.

[0059] As such, the asymmetric damping characteristics of the MR damper that occur during compression and tension operations, i.e., the FV curve, can be freely adjusted and set by appropriate design changes of the auxiliary flow path (50), such as the size of the first cross-sectional area (A1), the size of the second cross-sectional area (A2), and the difference between the first cross-sectional area (A1) and the second cross-sectional area (A2).

[0060] Additionally, referring to FIG. 5, the auxiliary flow path (50) according to the present embodiment may be formed such that the cross-sectional area gradually decreases from the first outlet (50a) to the second outlet (50b). Ultimately, the asymmetric damping characteristics of the MR damper that occur during compression and tension operations can be freely adjusted and set by changing the length of the auxiliary flow path (50) forming the nozzle structure.

[0061] Additionally, referring to FIG. 7, the auxiliary flow path (60) according to the present embodiment may include a large diameter section (61) extending from the first outlet (60a) with the same first cross-sectional area (A1), a small diameter section (62) extending from the second outlet (60b) with the same second cross-sectional area (A2), and an inclined connecting section (63) connecting the large diameter section (61) and the small diameter section (62). Ultimately, the asymmetric damping characteristics of the MR damper that occur during compression and tension operations may be freely adjusted and set by adjusting the lengths of the large diameter section (61), the small diameter section (62), and the inclined connecting section (63).

[0062] In addition, unlike the auxiliary flow path (50)(60) formed through the core body (22) shown in FIG. 5 and FIG. 7, with reference to FIG. 8, the auxiliary flow path (70) according to the present embodiment may be formed in the flux ring (24).

[0063] That is, as illustrated, the auxiliary channel (70) can be formed in the shape of a groove on the inner side of the flux ring (24).

[0064] Of course, although not shown, the auxiliary channel (70) may be formed in the shape of a groove on the outer surface of the flux ring (24).

[0065] At this time, the first cross-sectional area of ​​the first outlet (70a) and the second cross-sectional area of ​​the second outlet (70b) of the auxiliary channel (70) can be set by adjusting the width or depth of the groove formed by processing on the inner or outer surface of the flux ring (24).

[0066] In addition, the auxiliary flow path according to the present invention may be provided with an auxiliary flow path (50)(60) formed in the core body (22) as in FIG. 5 or 6, and an auxiliary flow path (70) formed on the inner or outer surface of the flux ring (24) as in FIG. 8.

[0067] Consequently, by appropriately changing the cross-sectional area, length, and cross-sectional shape of the auxiliary channel, the difference in cross-sectional area between the first and second outlets, and the number of auxiliary channels, the asymmetric damping characteristics of the MR damper generated during compression and tension operations can be freely adjusted and set. Accordingly, it becomes possible to effectively respond to the diverse ride comfort required by each occupant and the various driving characteristics of the vehicle.

[0068] The foregoing description of the present invention is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical spirit or essential features of the present invention. Therefore, the embodiments described above should be understood as illustrative in all respects and not restrictive. For example, each component described as a single unit may be implemented in a distributed manner, and components described as distributed may likewise be implemented in a combined form.

[0069] The scope of the present invention is defined by the claims set forth below, and all modifications or variations derived from the meaning and scope of the claims and equivalent concepts thereof should be interpreted as being included within the scope of the present invention. Explanation of the symbols

[0070] 10: Cylinder 20: Valve assembly 22: Core body 23: Coil 24: Flux Ring 25: Main Euro 50: Subsidy Euro 50a, 60a, 70a: First outlet 50b, 60b, 70b: Second outlet

Claims

Claim 1 An MR damper having asymmetric damping characteristics according to the direction of operation, comprising: a cylinder receiving an MR fluid; a core body configured to be movable within the cylinder by an external force and having a coil wound thereon; a flux ring coupled to the core body in a manner that surrounds the core body; and a valve assembly having a main flow path formed between the core body and the flux ring through which the MR fluid passes, wherein the valve assembly further has an auxiliary flow path formed through which the MR fluid passes in an area not affected by an electromagnetic field generated in the main flow path, and the auxiliary flow path has a first outlet into which the MR fluid flows during a compression operation and a second outlet into which the MR fluid flows during a tension operation, wherein the cross-sectional area of ​​the first outlet is larger than the cross-sectional area of ​​the second outlet. Claim 2 An MR damper having asymmetric damping characteristics according to the operating direction, characterized in that, in claim 1, the auxiliary flow path is formed such that the cross-sectional area gradually decreases from the first outlet to the second outlet. Claim 3 An MR damper having asymmetric damping characteristics according to the operating direction, characterized in that, in claim 1, the auxiliary flow path includes a large diameter section extending while having the same cross-sectional area as the first outlet, a small diameter section extending while having the same cross-sectional area as the second outlet, and an inclined connecting section connecting the large diameter section and the small diameter section. Claim 4 An MR damper having asymmetric damping characteristics according to the operating direction, characterized in that, in claim 1, the auxiliary flow path is formed through the core body. Claim 5 An MR damper having asymmetric damping characteristics according to the operating direction, characterized in that, in claim 1, the auxiliary flow path is formed in a groove shape on the inner surface of the flux ring. Claim 6 An MR damper having asymmetric damping characteristics according to the operating direction, characterized in that, in claim 1, the auxiliary flow path is formed in a groove shape on the outer surface of the flux ring. Claim 7 An MR damper having asymmetric damping characteristics according to the operating direction, characterized in that, in claim 1, the auxiliary flow path comprises a first auxiliary flow path formed through the core body and a second auxiliary flow path formed in a groove shape on the inner or outer surface of the flux ring.

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