Vehicle door stepless hovering system based on magnetorheological fluid, vehicle and method

Abstract

The invention relates to the technical field of vehicle doors, and discloses a vehicle door stepless hovering system based on magnetorheological fluid, a vehicle and a method. The system comprises a shell, a piston rod, a coil, a signal acquisition module and a current control module. An opening communicated with the cavity is formed in one end of the shell, and the cavity is filled with magnetorheological fluid. One end of the piston rod extends into the cavity from the opening; the piston rod is fixed to the vehicle door, and the shell is fixed to the vehicle body and can slide relative to each other along with rotation of the vehicle door. The opening is further provided with a sealing piece used for preventing liquid from leaking. The coil is wound around the outer portion of the shell and used for providing a magnetic field for the magnetorheological fluid in the cavity when powered on. The signal acquisition module is used for acquiring response signals in real time. And the current control module is used for adjusting the input current of the coil according to the response signal and a preset control strategy, so that the damping force generated by the magnetorheological fluid in the cavity to the piston rod is adjusted to realize the rotatable or stepless hovering of the vehicle door.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle doors, and in particular to a vehicle door stepless suspension system, a vehicle and a method based on magnetorheological fluid. Background Art

[0002] The design of traditional door hovering is mainly to be able to stably hover at a certain position after the door is opened to a certain angle, and will not automatically close due to gravity or other external forces. This design has several preset hovering positions, which is called "three-level hovering". On this basis, the researchers further proposed a door system that can hover at any position with stepless limit, so as to achieve the effect of stepless hovering while assisting the door opening and closing. For example, a mechanical brake is connected to the drive mechanism, and the door is hovered through friction resistance. When the drive mechanism stops working, the friction resistance provided by the mechanical brake can hinder the movement of the transmission rod, so that the door is kept at a preset angle to achieve hovering. Another solution is to control the movement of the door through an electric drive, slow down the motor when receiving the hovering command, and then provide a hovering holding force for the door through an electromagnetic brake. These technical structures are complex, and all use friction to provide the force to keep the door hovering. As the number of uses increases, the friction surface will become smooth and may not provide enough force, resulting in a weakening of the hovering effect. Summary of the invention

[0003] In order to solve the technical problems in the existing vehicle door stepless suspension technology, such as poor suspension effect and limited system service life due to friction loss of mechanical parts, the present invention provides a vehicle door stepless suspension system, vehicle and method based on magnetorheological fluid.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] The invention discloses a vehicle door stepless suspension system based on magnetorheological fluid, comprising: a shell, a piston rod, a coil, a signal acquisition module and a current control module.

[0006] One end of the shell is provided with an opening which is connected with a cavity inside the shell, and the cavity is filled with magnetorheological fluid.

[0007] One end of the piston rod extends into the cavity from the opening; one of the piston rod and the shell is fixedly installed on the vehicle door, and the other is fixedly installed on the vehicle body, and the piston rod and the shell can slide relative to each other as the vehicle door rotates, and a seal is also provided at the opening to prevent leakage of magnetorheological fluid.

[0008] The coil is wound around the exterior of the housing and is used to provide a magnetic field to the magnetorheological fluid in the cavity when power is supplied.

[0009] The signal acquisition module is used to collect the response signal reflecting the door status in real time.

[0010] The current control module is used to adjust the input current of the coil according to the response signal and a preset control strategy, thereby adjusting the damping force generated by the magnetorheological fluid in the cavity on the piston rod to achieve rotation or stepless suspension of the door.

[0011] As a further improvement of the above scheme, the signal acquisition module includes a pressure acquisition unit and an angle acquisition unit; the pressure acquisition unit is installed on the door handle and is used to collect a first signal reflecting the force F1 on the handle; the angle acquisition unit is used to collect a second signal reflecting the opening and closing angle C1 of the door.

[0012] As a further improvement of the above scheme, the control strategy is as follows:

[0013] It is determined whether the door opening and closing angle C1 is at a preset initial angle value C0. If so, it is determined that the door is closed, the current control module is in a non-working state, and no control operation is performed; otherwise, it is determined that the door is open, the current control module enters the working state, and analyzes the changes of F1 and C1, and makes the following decisions respectively:

[0014] When F1≥F0, the rotatable mode is started and the input current of the coil is adjusted to 0; wherein F0 is the preset upper limit of the force;

[0015] When F1<F0 and C1 remains unchanged within a preset time threshold t, the hovering mode is started, and the input current of the coil is adjusted to a preset first current threshold I1;

[0016] In the hovering mode, if the change value of C1 exceeds a preset upper limit of the angle change and F1 remains unchanged, the input current of the coil is adjusted to a preset second current threshold value I2; wherein 0<I1<I2.

[0017] As a further improvement of the above solution, the hovering system further includes: a connecting piece.

[0018] The connecting piece has a tubular structure and one end is inserted into the opening; the cross-section of the outer wall of the connecting piece and the cross-section projection of the inner wall of the outer shell match each other, and the two are relatively fixed; a first sealing ring is arranged between the connecting piece and the outer shell to achieve one-way sealing; the cross-section of the inner wall of the connecting piece and the cross-section projection of the piston rod match each other, and the two are in sliding contact; three fixed second sealing rings are arranged on the inner wall of the connecting piece at intervals along the sliding direction to achieve two-way sealing.

[0019] As a further improvement of the above solution, the housing, the connecting piece and the piston rod are all arc-shaped along the extension direction and have circular cross-sections.

[0020] As a further improvement of the above solution, a section of the piston rod extending into the cavity is an extending section, and a gap for allowing the magnetorheological fluid to flow exists between the circumferential outer edge of the extending section and the circumferential inner wall of the shell.

[0021] As a further improvement of the above scheme, the end of the extension section is integrally connected with a first disc; the projection area of ​​the circumferential outer edge of the first disc is larger than the projection area of ​​the circumferential outer edge of the extension section; at least one first disc is provided, and when there are multiple first discs, they are distributed in sequence along the extension direction of the extension section; the first disc is provided with at least one guide hole parallel to the extension direction of the extension section along the circumferential direction.

[0022] As a further improvement of the above solution, a second disc is integrally connected to the middle portion of the outer wall of the connecting member, and an end surface of the second disc and an end surface of the outer shell are fixedly connected by a plurality of screws.

[0023] The present invention also discloses a vehicle, comprising a vehicle body and a vehicle door, and also comprising the above-mentioned vehicle door stepless suspension system.

[0024] The present invention also discloses a method for steplessly suspending a vehicle door based on magnetorheological fluid, which is applied to the above-mentioned steplessly suspending system for a vehicle door. The method comprises the following steps S1 to S2.

[0025] S1. Real-time collection of response signals reflecting the state of the vehicle door, wherein the response signals include a first signal reflecting the force F1 on the handle and a second signal reflecting the opening and closing angle C1 of the vehicle door.

[0026] S2. Determine whether the door opening angle C1 is at a preset initial angle value C0. If so, the door is determined to be closed, the current control module is in a non-working state, and no control operation is performed; otherwise, the door is determined to be open, the current control module enters a working state, and analyzes the changes of F1 and C1, and makes the following decisions respectively:

[0027] When F1≥F0, the rotatable mode is started and the input current of the coil is adjusted to 0; wherein F0 is the preset upper limit of the force;

[0028] When F1<F0 and C1 remains unchanged within a preset time threshold t, the hovering mode is started, and the input current of the coil is adjusted to a preset first current threshold I1;

[0029] In the hovering mode, if the change value of C1 exceeds a preset upper limit of the angle change and F1 remains unchanged, the input current of the coil is adjusted to a preset second current threshold value I2; wherein 0<I1<I2.

[0030] Compared with the prior art, the present invention has the following beneficial effects:

[0031] 1. The present invention uses magnetorheological fluid for stepless suspension of car doors. Magnetorheological fluid can achieve precise viscosity adjustment according to the control of external electromagnetic field, provide precise suspension force for the door suspension system, and then dynamically adjust input current, magnetic field strength and viscosity of magnetorheological fluid by combining door information collection and electronic control, so as to adjust the size of door suspension force, and realize intelligent adjustment and control of door suspension mode. Stepless suspension allows the door to stay at different opening angles, improves the comfort and convenience of door opening, and can reduce the friction loss of mechanical transmission components and extend the service life of the suspension system.

[0032] 2. In the present invention, multiple sealing rings are used for bidirectional sealing between the connector and the piston rod, and a single sealing ring is used for unidirectional sealing between the connector and the housing. The two sealing methods can effectively reduce the leakage of magnetorheological fluid during the feeding process of the piston rod. The use of screws and gaskets ensures a tight mechanical connection between the housing and the connector, and enhances the stability and strength of the connection. This connection can withstand the vibration and force during the operation of the equipment, and avoids failures and damage caused by looseness. At the same time, it makes the installation and maintenance of the hovering system more convenient and efficient, and reduces the complexity and cost of maintenance. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a schematic diagram of the three-dimensional structure of a vehicle door stepless suspension system based on magnetorheological fluid in an embodiment of the present invention.

[0034] Figure 2 for Figure 1 Schematic cross-sectional view of the center door stepless suspension system from the main perspective.

[0035] Figure 3 Schematic diagram of the relative position of the piston rod submerged by the magnetorheological fluid in the cavity in an embodiment of the present invention.

[0036] Figure 4 It is a schematic structural diagram of a case where a plurality of first discs are provided at the insertion section of the piston rod in an embodiment of the present invention.

[0037] Figure 5 Schematic diagram of the interaction among the signal acquisition module, the current control module and the coil in an embodiment of the present invention.

[0038] Figure 6 Schematic diagram of the arrangement of the pressure collection unit on the door handle in an embodiment of the present invention.

[0039] Figure 7 It is a logical schematic diagram of a method for stepless suspension of a vehicle door based on magnetorheological fluid in an embodiment of the present invention.

[0040] In the figure: 1. outer shell; 11. opening; 12. cavity; 2. piston rod; 21. first disc; 210. guide hole; 3. coil; 4. signal acquisition module; 41. pressure acquisition unit; 411. inner pressure sensor; 412. outer pressure sensor; 42. angle acquisition unit; 5. current control module; 6. connector; 62. second disc; 71. first sealing ring; 72. second sealing ring; 8. screw. DETAILED DESCRIPTION

[0041] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0042] See also Figures 1 to 3 This embodiment provides a vehicle door stepless suspension system based on magnetorheological fluid, including: a housing 1, a piston rod 2, a coil 3, a signal acquisition module 4 and a current control module 5, and may also include a connector 6.

[0043] In this embodiment, the housing 1, the connecting member 6, and the piston rod 2 may all be arc-shaped along the extension direction, corresponding to the rotation angle of the door on the vehicle body. The cross-sections of the housing 1, the connecting member 6, and the piston rod 2 may all be circular. Of course, in other embodiments, the three may also be set to be linear along the extension direction, similar to a linear cylinder / hydraulic cylinder, and some transmission devices (such as multi-link) may be used to drive the piston rod 2 to perform linear motion by utilizing the rotation of the door.

[0044] One end of the housing 1 is provided with an opening 11 communicating with a cavity 12 inside the housing 1, and the other end is a closed end. The cavity 12 is filled with magnetorheological fluid.

[0045] Magnetorheological fluid is a new type of fluid with controllable fluidity. When there is no external magnetic field, the magnetic particles are suspended in the base liquid and randomly distributed, showing a linear viscosity Newtonian fluid, which is no different from ordinary hydraulic suspension. Under the action of an external magnetic field, it can change from a low-viscosity Newtonian fluid to a semi-solid with higher viscosity in a short time (10ms). The outside world calls it the magnetorheological effect. Magnetorheological fluid can achieve continuous reversible transformation from liquid to quasi-solid in milliseconds. As the magnetic field strength increases, its viscosity also increases.

[0046] One end of the piston rod 2 extends from the opening 11 into the cavity 12 and is in full contact with the magnetorheological fluid. The section of the piston rod 2 extending into the cavity 12 is the extending section. In this embodiment, the housing 1 is fixedly mounted on the vehicle body, and the piston rod 2 is fixedly mounted on the vehicle door. Of course, in other embodiments, the mounting carriers of the housing 1 and the piston rod 2 may be opposite. The piston rod 2 and the housing 1 can slide relative to each other as the vehicle door rotates. A seal is also provided at the opening 11 to prevent the magnetorheological fluid from leaking out.

[0047] It should be noted that, in addition to the magnetorheological fluid, the cavity 12 is also filled with a certain amount of air. The amount of magnetorheological fluid filled in the cavity 12 can be determined according to the volume occupied by the extended section of the piston rod 2 when it is fully extended into the cavity 12. When the extended section is fully extended into the cavity 12, the magnetorheological fluid needs to submerge the piston rod 2 as much as possible. Figure 3 As shown ( Figure 3 A in the figure represents the boundary between magnetorheological fluid and air), which can ensure that when a magnetic field is provided for the magnetorheological fluid, sufficient damping force is provided for the piston rod 2, and at the same time ensure that the magnetorheological fluid will not be expelled from the cavity 12 during the movement of the piston rod 2 in the cavity 12.

[0048] The connector 6 is tubular and one end is inserted into the opening 11. The cross-section of the outer wall of the connector 6 and the cross-section projection of the inner wall of the housing 1 are consistent with each other, and the two are relatively fixed. In this embodiment, a second disc 62 is integrally connected to the middle of the outer wall of the connector 6, and the end surface of the second disc 62 and the end surface of the housing 1 can be fixedly connected by multiple screws 8. A gasket can be arranged between the screws 8 and the second disc 62 to ensure the tightness of the threaded fit.

[0049] A first sealing ring 71 is provided between the connector 6 and the housing 1 to achieve one-way sealing and prevent the magnetorheological fluid from leaking from the matching gap between the connector 6 and the housing 1. Of course, in other embodiments, the connector 6 can also be an integrated structure with the housing 1, which can further ensure the reliability of the seal. The cross-section of the inner wall of the connector 6 and the cross-section projection of the piston rod 2 are consistent with each other, and the two are in sliding contact; three fixed second sealing rings 72 are provided at intervals along the sliding direction on the inner wall of the connector 6 to achieve two-way sealing, thereby ensuring that the magnetorheological fluid is prevented from leaking when the piston rod 2 is pushed out from the cavity 12, and at the same time, external contaminants are prevented from entering the cavity 12 when the piston rod 2 is pushed into the cavity 12.

[0050] There is a gap between the circumferential outer edge of the extension section and the circumferential inner wall of the housing 1 for the magnetorheological fluid to flow, so that the flow exchange of the magnetorheological fluid is not affected when the extension section moves in the cavity 12. The end of the extension section is integrally connected to a first disk 21; the circumferential outer edge projection area of ​​the first disk 21 is larger than the circumferential outer edge projection area of ​​the extension section. Figure 4As shown, in some embodiments, the first disc 21 can also be set to other shapes, and the number of the first disc 21 can also be set to multiple. The multiple first discs 21 are spaced apart along the extension direction at the end of the extension section to form a structure similar to an insulator, so that the contact area of ​​the magnetorheological fluid of the piston rod 2 can be increased (for example, in an anchor shape); the first disc 21 can be provided with six guide holes 210 pointing to the gap along the circumferential direction. By setting the first disc 21, the magnetorheological fluid can stay near the front and back sides of the first disc 21. The first disc 21 increases the force-bearing area compared to the end face of the piston rod 2. When the magnetorheological fluid is subjected to the magnetic field to produce the magnetorheological effect, the damping force on the piston rod 2 as a whole can be increased. At the same time, the guide holes 210 can facilitate the flow of the magnetorheological fluid when the magnetic field is not applied.

[0051] It should be noted that Figure 1 and Figure 2 The piston rod 2 in the figure is only for illustration. In actual application, the extending section of the piston rod 2 can be set to a relatively thin rod body (such as Figure 3 and Figure 4 As shown in the figure, for example, the cross-sectional ratio of the piston rod 2 and the cavity 12 is set to 1:5, because the anchor-shaped first disc 21 is the main source of the damping force, as long as the structural strength of the piston rod 2 itself can meet the requirements. In this way, when pushing into the cavity 12, there will be no large resistance due to the compression of the air in the cavity. In some embodiments, after the various components of the system are assembled, the air pressure in the cavity 12 can be slightly lower than the atmospheric pressure by vacuuming, which can also avoid the piston rod 2 from encountering obvious resistance during the process of pushing into the cavity 12, thereby ensuring that the door can be opened and closed normally.

[0052] The coil 3 is wound around the outside of the housing 1 and is used to provide a magnetic field for the magnetorheological fluid in the cavity 12 when power is supplied. The coil 3 can be connected to the circuit system of the vehicle body through a wire. When the wire is powered, a magnetic field is generated around the coil 3. The strength of the magnetic field is related to the input current and the number of turns of the coil 3. Under the condition that the number of turns of the coil 3 is fixed, the greater the input current, the greater the magnetic field strength. At the same time, the piston rod 2 can enhance the magnetic field strength as an iron core.

[0053] See also Figure 5 The signal acquisition module 4 is used to acquire the response signal reflecting the state of the door in real time. In this embodiment, the signal acquisition module 4 may include a pressure acquisition unit 41 and an angle acquisition unit 42.

[0054] The pressure collection unit 41 is installed on the handle of the vehicle door and is used to collect a first signal reflecting the force F1 on the handle.

[0055] See also Figure 6The pressure collection unit 41 may include at least two pressure sensors, which are placed at appropriate positions on the inner and outer sides of the door handle. Usually, when the user holds the handle to open the door (the handle is pulled), the inner pressure sensor 411 will be pressed and generate an electrical signal; and when the user closes the door (the handle is pushed), the outer pressure sensor 412 will be pressed and generate an electrical signal. Regardless of which pressure sensor generates the electrical signal, it can be used as the basis for the pressure collection unit 41 to collect the first signal, because the function of the signal is only to judge whether the user is holding the door handle.

[0056] The angle acquisition unit 42 is used to collect a second signal reflecting the opening and closing angle C1 of the vehicle door. The angle acquisition unit 42 can be a photoelectric sensor or a Hall sensor, which is installed near the rotating shaft of the vehicle door and can monitor the opening and closing angle of the vehicle door. Those skilled in the art can arrange it by themselves according to common technical knowledge, which will not be repeated here. In some embodiments, the opening and closing angle C1 can also be directly obtained from the vehicle door angle monitoring unit that comes with the vehicle when it leaves the factory.

[0057] The pressure acquisition unit 41 and the angle acquisition unit 42 can periodically report the status to the current control module 5 (once every 400ms).

[0058] The current control module 5 is used to adjust the input current of the coil 3 according to the response signal and a preset control strategy, thereby adjusting the damping force generated by the magnetorheological fluid in the cavity 12 on the piston rod 2 to achieve rotation or stepless suspension of the door.

[0059] The current control module 5 is an electronic device, including a current amplifier, a memory, a processor, and a computer program stored in the memory.

[0060] The control strategy is as follows:

[0061] It is determined whether the door opening angle C1 is at a preset initial angle value C0.

[0062] Non-working state: when the door opening and closing angle C1 is at a preset initial angle value C0, it is determined that the door is completely closed, and the current control module 5 is in a low-power standby state without performing any control operation.

[0063] Working state: If the door opening and closing angle C1 is not at a preset initial angle value C0, the door is determined to be open, the current control module 5 is activated, enters the working state, and starts to analyze the changes of F1 and C1, and makes the following decisions respectively:

[0064] ① Rotatable mode: When the door handle is in an operating state (such as being pulled or pushed), it indicates that the user wants to change the opening and closing state of the door. At this time, it is determined whether F1≥F0 is established. If so, the current control module starts the rotatable mode and adjusts the input current of the coil 3 to 0; where F0 is the preset upper force limit. At this time, the magnetorheological fluid is in a low viscosity state, and the damping force on the piston rod 2 is extremely small and can be ignored, so the door can be easily opened or closed.

[0065] ②Hovering mode: When the door needs to be kept in a certain position (such as half-open state), when the user wants to suspend the door, release the door handle, and then judge whether F1<F0 and C1 remain unchanged within a preset time threshold t. If it is satisfied, the hovering mode is started, and the input current of the coil 3 is adjusted to the preset first current threshold I1, so that a strong magnetic field is generated inside the coil 3. Under the action of the magnetic field, the ferromagnetic particles in the magnetorheological fluid are quickly arranged into a chain or columnar structure, resulting in a sharp increase in the viscosity of the fluid. At this time, the magnetorheological fluid changes from a low-viscosity Newtonian fluid to a high-viscosity semi-solid state. The high-viscosity magnetorheological fluid produces a great damping force on the piston rod 2, hindering the rotation of the door, and the door enters the hovering state. The door rotation needs to overcome the damping force of the magnetorheological fluid on the piston rod 2. When the door reaches the desired position and remains hovering, the circuit control module 5 maintains the current intensity in the coil 3 unchanged to ensure that the magnetorheological fluid maintains its high viscosity state and continues to apply damping force to the piston rod 2.

[0066] The magnitude of this damping force can be controlled by adjusting the magnetic field strength and the composition of the magnetorheological fluid, thereby achieving precise hovering of the door at any position.

[0067] In the hovering mode, the current control module 5 continuously monitors the door rotation angle and the handle force. If a slight change in the door position is detected, that is, the change value of C1 exceeds a preset angle change upper limit, while F1 remains unchanged, the current amplifier is used to increase the input current of the coil 3 and adjust the input current of the coil 3 to a preset second current threshold value I2; wherein 0<I1<I2. This further enhances the damping force and improves the door's ability to resist interference from gravity, wind or other external forces.

[0068] This embodiment also provides a vehicle, which includes a vehicle body, a door, and the above-mentioned door stepless suspension system.

[0069] See also Figure 7 This embodiment also provides a method for steplessly suspending a vehicle door based on magnetorheological fluid, which is applied to the above-mentioned steplessly suspending vehicle door system. The method includes the following steps S1 to S2.

[0070] S1. Real-time collection of response signals reflecting the state of the vehicle door, wherein the response signals include a first signal reflecting the force F1 on the handle and a second signal reflecting the opening and closing angle C1 of the vehicle door.

[0071] S2. Determine whether the door opening angle C1 is at a preset initial angle value C0. If so, the door is determined to be closed, and the current control module 5 is in a non-working state and does not perform any control operation. Otherwise, the door is determined to be open, and the current control module 5 enters a working state, and analyzes the changes of F1 and C1, and makes the following decisions respectively:

[0072] When F1≥F0, the rotatable mode is started and the input current of coil 3 is adjusted to 0; wherein F0 is the preset upper limit of the force;

[0073] When F1<F0 and C1 remains unchanged within a preset time threshold t, the hovering mode is started, and the input current of the coil 3 is adjusted to a preset first current threshold I1;

[0074] In the hovering mode, if the change value of C1 exceeds a preset upper limit of the angle change and F1 remains unchanged, the input current of the coil 3 is adjusted to a preset second current threshold value I2; wherein 0<I1<I2.

[0075] The door stepless suspension method has the same principle as the above control strategy, which will not be described in detail here.

[0076] The above description is only a preferred specific implementation manner of the present invention, but the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical scheme and inventive concept of the present invention within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A car door stepless suspension system based on magnetorheological fluid, characterized in that: include: The housing (1) has an opening (11) at one end thereof which is connected to a cavity (12) inside the housing, and the cavity (12) is filled with a magnetorheological fluid; A piston rod (2) has one end extending from the opening (11) into the cavity (12); one of the piston rod (2) and the housing (1) is fixedly mounted on the vehicle door, and the other is fixedly mounted on the vehicle body, and the piston rod (2) and the housing (1) can slide relative to each other as the vehicle door rotates, and a sealing member for preventing magnetorheological fluid from leaking out is also provided at the opening (11); A coil (3) wound around the outside of the housing (1) and used to provide a magnetic field for the magnetorheological fluid in the cavity (12) when electricity is supplied; A signal acquisition module (4), which is used to acquire a response signal reflecting the state of the vehicle door in real time; A current control module (5) is used to adjust the input current of the coil (3) according to the response signal and in accordance with a preset control strategy, thereby adjusting the damping force generated by the magnetorheological fluid in the cavity (12) on the piston rod (2) to achieve rotation or stepless suspension of the vehicle door.

2. The vehicle door stepless suspension system based on magnetorheological fluid according to claim 1, characterized in that: The signal acquisition module (4) comprises a pressure acquisition unit (41) and an angle acquisition unit (42); the pressure acquisition unit (41) is installed on the handle of the vehicle door and is used to acquire a first signal reflecting the force F1 applied to the handle; the angle acquisition unit (42) is used to acquire a second signal reflecting the opening and closing angle C1 of the vehicle door.

3. The stepless suspension system for vehicle doors based on magnetorheological fluid according to claim 2, characterized in that: The control strategy is as follows: It is determined whether the door opening and closing angle C1 is at a preset initial angle value C0. If so, it is determined that the door is closed, and the current control module (5) is in a non-working state and does not perform any control operation. Otherwise, it is determined that the door is open, and the current control module (5) enters a working state, and analyzes the changes of F1 and C1, and makes the following decisions respectively: When F1≥F0, the rotatable mode is started and the input current of the coil (3) is adjusted to 0; wherein F0 is a preset upper limit of the force; When F1<F0 and C1 remains unchanged within a preset time threshold t, the hovering mode is started, and the input current of the coil (3) is adjusted to a preset first current threshold I1; In the hovering mode, if the change value of C1 exceeds a preset upper limit of the angle change and F1 remains unchanged, the input current of the coil (3) is adjusted to a preset second current threshold value I2; wherein 0<I1<I2.

4. The vehicle door stepless suspension system based on magnetorheological fluid according to claim 1, characterized in that: Also includes: The connecting piece (6) has a tubular structure and one end is inserted into the opening (11); the cross-section of the outer wall of the connecting piece (6) and the cross-section projection of the inner wall of the outer shell (1) match each other, and the two are relatively fixed; a first sealing ring (71) is arranged between the connecting piece (6) and the outer shell (1) to achieve one-way sealing; the cross-section of the inner wall of the connecting piece (6) and the cross-section projection of the piston rod (2) match each other, and the two are in sliding contact; three fixed second sealing rings (72) are arranged at intervals on the inner wall of the connecting piece (6) along the sliding direction to achieve two-way sealing.

5. The vehicle door stepless suspension system based on magnetorheological fluid according to claim 4, characterized in that: The housing (1), the connecting piece (6) and the piston rod (2) are all arc-shaped along the extension direction and have circular cross-sections.

6. The vehicle door stepless suspension system based on magnetorheological fluid according to claim 5, characterized in that: The section of the piston rod (2) that extends into the cavity (12) is the extending section, and there is a gap between the circumferential outer edge of the extending section and the circumferential inner wall of the housing (1) for allowing the magnetorheological fluid to flow.

7. The vehicle door stepless suspension system based on magnetorheological fluid according to claim 6, characterized in that: The end of the extension section is integrally connected with a first disk (21); the projection area of ​​the circumferential outer edge of the first disk (21) is larger than the projection area of ​​the circumferential outer edge of the extension section; at least one first disk (21) is provided, and when there are multiple first disks (21), they are sequentially spaced and distributed along the extension direction of the extension section; the first disk (21) is provided with at least one guide hole (210) parallel to the extension direction of the extension section along the circumferential direction.

8. The vehicle door stepless suspension system based on magnetorheological fluid according to claim 4, characterized in that: A second disc (62) is integrally connected to the middle portion of the outer wall of the connecting member (6), and an end surface of the second disc (62) and an end surface of the outer shell (1) are fixedly connected by a plurality of screws (8).

9. A vehicle, comprising a vehicle body and a vehicle door, characterized in that: It also includes a vehicle door stepless suspension system based on magnetorheological fluid as described in any one of claims 1 to 8.

10. A method for stepless suspension of a vehicle door based on magnetorheological fluid, characterized in that: The method for a vehicle door stepless suspension system based on magnetorheological fluid as claimed in any one of claims 1 to 8 comprises the following steps: S1. Real-time acquisition of response signals for reflecting the state of the door, the response signals including a first signal reflecting the force F1 of the handle and a second signal reflecting the opening and closing angle C1 of the door; S2. Determine whether the door opening angle C1 is at a preset initial angle value C0. If so, the door is determined to be closed, and the current control module (5) is in a non-working state and does not perform any control operation. Otherwise, the door is determined to be open, and the current control module (5) enters a working state, and analyzes the changes of F1 and C1, and makes the following decisions respectively: When F1≥F0, the rotatable mode is started and the input current of the coil (3) is adjusted to 0; wherein F0 is a preset upper limit of the force; When F1<F0 and C1 remains unchanged within a preset time threshold t, the hovering mode is started, and the input current of the coil (3) is adjusted to a preset first current threshold I1; In the hovering mode, if the change value of C1 exceeds a preset upper limit of the angle change and F1 remains unchanged, the input current of the coil (3) is adjusted to a preset second current threshold value I2; wherein 0<I1<I2.

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