Composite electromagnetic shock absorber and control method

Abstract

The invention discloses a composite electromagnetic shock absorber and a control method, the composite electromagnetic shock absorber comprises an upper support, a magnetorheological damper, a planetary roller screw, a rotor motor, a spring and a lower support, the magnetorheological damper is internally provided with an upper end cover, a wedge-shaped rotor, an O-shaped sealing ring, a stator, a coil, a check ring, a bearing, magnetorheological fluid, a coil cover and a lower end cover; a bearing, a linear bearing, a lead screw nut, a clamping ring, a retainer, a pin roller, a lead screw, a cylinder body and a cover plate are arranged in the planetary pin roller lead screw, a motor rotor is installed on the lead screw nut, a motor stator is installed on the cylinder body, a lower end cover of the magnetorheological damper is connected with the cylinder body, and a rotor of the magnetorheological damper is connected with the lead screw nut. The invention further provides a control method of the combined motor and the magnetorheological damper. The electromagnetic shock absorber has the beneficial effects that the bearing capacity of the electromagnetic shock absorber is improved; the asymmetric damping characteristic of the shock absorber is realized; the problem that output damping of a traditional electromagnetic shock absorber is too small at a low speed is solved, and harm caused by faults of a single system is reduced.

Description

Technical Field

[0001] The present application belongs to the technical field of vibration dampers, and specifically relates to a composite electromagnetic vibration damper and a control method thereof. Background Art

[0002] Shock absorbers are important components of automobile suspension systems, and their purpose is to consume vibration energy to improve the ride comfort of vehicles. At present, mainstream electromagnetic shock absorbers mostly use ball screws as motion conversion structures, which have limited bearing capacity and impact resistance. Although the motor in the shock absorber can respond quickly and adjust the damping force, the magnitude of its force is related to the relative movement speed between the two supports. It cannot provide a large damping force at low speeds, which further limits the improvement of vibration reduction performance. In addition, the working process of the shock absorber can be divided into two stages: compression and extension. During the compression process, a smaller damping force can enable the spring to better play its elastic role, thereby alleviating the impact. During the extension process, a larger damping force can quickly attenuate the vibration, allowing the vehicle to return to its original position quickly and stably. However, the current electromagnetic shock absorbers do not have the characteristic of asymmetric damping. Therefore, in order to further explore the performance of electromagnetic shock absorbers, it is necessary to improve the damping output force at low speeds and design asymmetric damping in the compression and extension processes as needed in order to obtain better suspension performance. Summary of the invention

[0003] In order to overcome the shortcomings of the above-mentioned prior art, the present invention provides a composite electromagnetic vibration absorber and a control method. The invention uses a planetary roller screw to enhance the load-bearing capacity, uses a magnetorheological damper to compensate for the motor performance defects, and ensures that damping control can still be achieved when a single system fails.

[0004] To achieve the above object, the technical solution of the present invention is:

[0005] A composite electromagnetic vibration absorber comprises an upper support, a magnetorheological damper, a planetary roller screw, a rotor motor, a spring and a lower support.

[0006] The magnetorheological damper is internally provided with an upper end cover, a wedge-shaped rotor, an O-ring, a stator, a coil, a retaining ring, a bearing, a magnetorheological fluid, a coil cover and a lower end cover, and the upper end cover of the magnetorheological damper is connected to a planetary roller screw.

[0007] The rotor is a hollow shaft with a keyway inside for connecting the lead screw nut. The coil is wound on the outside of the stator and is sealed and protected by the cylinder body. The coil cover is provided with a wire outlet slot, and the lead wire of the coil is led out to the outside of the damper through the wire outlet slot. The retaining ring and the stator constitute a closed area, and magnetorheological fluid is injected into the interior. The sealing ring is used to prevent the magnetorheological fluid from leaking and foreign impurities from entering.

[0008] The planetary roller screw includes a bearing, a linear bearing, a screw nut, a clamping ring, a retaining frame, a roller, a screw, a cylinder body and a cover plate. The screw is connected to the lower support. The motor rotor is installed on the screw nut, and the motor stator is installed on the cylinder body. The motor is a three-phase asynchronous motor.

[0009] A spring is arranged between the lower support and the planetary roller screw cylinder body, and is responsible for bearing the weight of the vehicle body and maintaining the height and stability of the shock absorber.

[0010] The screw nut drives the motor to rotate, which can generate an induced electromotive force and an induced current in the circuit. The current can cause the motor to experience a torque that hinders the relative motion. The torque can be transmitted to both ends of the shock absorber through the planetary roller screw structure, which is the damping force of the shock absorber.

[0011] The magnitude of the induced current is proportional to the rotation speed of the motor. When the motor rotates at a low speed, the induced current generated inside the motor is small, so the rotation speed of the motor limits the magnitude of the damping force in the shock absorber.

[0012] A magnetorheological damper is a device that changes the internal damping force by changing the viscosity of the liquid. The magnetorheological fluid inside it will undergo rheological phenomena under the action of an external magnetic field, forming a large number of chain structures and network structures, thus generating a damping force on the movement.

[0013] The damping force of the magnetorheological damper is mainly controlled by the magnetic field rather than directly by the speed. Therefore, when the magnetic field strength remains unchanged, a large damping force can still be generated even at a low speed. This device makes up for the performance defects of motor vibration reduction and can achieve optimal vibration reduction performance.

[0014] The magnetorheological damper rotor is provided with a wedge-shaped structure, which ensures that the magnetorheological damper has different damping characteristics according to different rotation directions. This asymmetric damping characteristic enables the shock absorber to provide different damping forces in tension and compression movements, thereby better adapting to different driving conditions.

[0015] A control method for a composite electromagnetic vibration absorber comprises the following steps:

[0016] Step 1: Dynamically select the working mode of the motor according to the actual driving conditions. When the damping force is effective for vibration control, the motor outputs the damping force to the outside, thereby reducing the energy consumption of the system. Otherwise, the motor outputs the driving force to the outside, thereby maximizing the vehicle's handling and stability.

[0017] Step 2: The damping force generated by the motor is proportional to the equivalent current in the motor's internal coil, and the equivalent current is proportional to the motor speed and circuit resistance. The maximum damping force allowed to be output by the motor under the current working conditions is derived.

[0018] Step three, determine whether the maximum damping force allowed to be output by the motor can meet the vibration reduction requirements. If not, power the magnetorheological damper to increase the output damping force of the system.

[0019] Step 4: determine whether the motor system fails based on the current in the motor circuit. When the motor fails, the damping force required by the system is provided by the magnetorheological damper.

[0020] The beneficial effects of the present invention are as follows

[0021] 1. The present invention utilizes a planetary roller screw instead of a ball screw as a motion conversion mechanism of the shock absorber, thereby improving the load-bearing capacity and impact resistance of the electromagnetic shock absorber.

[0022] 2. The magnetorheological damper is used to compensate for the problem of too small output damping of the motor and realize the asymmetric damping characteristics of the shock absorber, which not only improves the shock absorption performance of the shock absorber, but also ensures the rapid attenuation ability of vibration.

[0023] 3. Combined with the active and semi-active control of the motor, the energy consumption of the shock absorber is reduced while ensuring that the shock absorber has good vibration reduction performance.

[0024] 4. By combining magnetorheological damper control and motor control, when a single system fails, the damping force can be controlled by another system, which can reduce the risk of device failure. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] In order to more clearly illustrate the technical solution of the present invention, the following is a brief introduction to the accompanying drawings, in which:

[0026] Figure 1 It is a schematic diagram of a composite electromagnetic suspension;

[0027] Figure 2 This is a schematic diagram of a planetary roller screw and a motor;

[0028] Figure 3 is a schematic diagram of a magnetorheological damper;

[0029] Figure 4 It is a schematic diagram of a wedge-shaped rotor;

[0030] Figure 5 It is a schematic diagram of the control method;

[0031] Legend: upper support 1; magnetorheological damper 2; upper end cover 201; wedge-shaped rotor 202; O-rings 203 and 208; stator 204; coil 205; retaining ring 206; bearing 207; magnetorheological fluid 209; coil cover 210; lower end cover 211; planetary roller screw 3; bearings 301, 304 and 308; linear bearing 302; screw nut 303; retaining ring 305; cage 306; roller 307; screw 309; cylinder body 310; cover plate 311; rotor motor 4; motor rotor 401; motor stator 402; spring 5; lower support 6. Specific implementation plan

[0032] In order to make the technical solution of the present invention better understood by those skilled in the art or other fields, the specific implementation methods of the present invention are further described below.

[0033] See also Figure 1 , Figure 2 and Figure 3 As shown, the present invention is installed in the suspension system of an automobile, and its technical solution includes an upper support 1, a magnetorheological damper 2, a planetary roller screw 3, a rotor motor 4, a spring 5, and a lower support 6.

[0034] The spring 5 is installed between the planetary roller screw 3 and the lower support 6 to bear the weight of the vehicle body and maintain the height and stability of the shock absorber.

[0035] The planetary roller screw includes screw bearings 301, 304 and 308, a linear bearing 302, a screw nut 303, a clamping ring 305, a retaining frame 306, a roller 307, a screw 309, a cylinder body 310, and a cover plate 311. The screw 309 is connected to the lower support 6, the screw nut 303 is equipped with a motor rotor 401, and the cylinder body 310 is equipped with a motor stator 402.

[0036] The magnetorheological damper is internally provided with an upper end cover 201, a wedge-shaped rotor 202, O-rings 203 and 208, a stator 204, a coil 205, a retaining ring 206, a bearing 207, a magnetorheological fluid 209, a coil cover 210, and a lower end cover 211. The wedge-shaped rotor 202 is a hollow shaft with a keyway provided inside for connecting the screw nut 303. The lower end cover 211 is connected to the planetary roller screw cylinder 310, and the upper end cover 201 of the rheological damper is connected to the upper support 1.

[0037] When relative movement occurs between the upper and lower supports, the lead screw 309 will move up and down to drive the lead screw nut 303 to rotate. At this time, the motor rotor 401 installed on the lead screw nut 303 will generate a resistance torque due to the existence of the induced current, but the magnitude of the induced current is proportional to the relative movement speed between the upper and lower supports. Therefore, when the movement speed is low, the motor cannot be used to generate a large damping force.

[0038] Magnetorheological dampers mainly use the rheological properties of magnetorheological fluid under the action of a magnetic field to adjust the damping force. When the magnetic field strength increases, the viscosity of the liquid will increase, thereby generating a larger damping force. The generation of this damping force is closely related to the magnetic field strength and has little direct relationship with the rotational speed. Therefore, a magnetorheological damper can be used to generate a larger damping force at low speeds, thereby compensating for the above-mentioned defects.

[0039] like Figure 4 As shown, the rotor 202 of the magnetorheological damper has a wedge-shaped structure. When the shock absorber is compressed, the rotor rotates counterclockwise. At this time, the wedge-shaped section can guide the liquid to flow through the channel, reduce the generation of turbulence, and thus reduce the rotational resistance of the rotor. When the shock absorber is stretched, the rotor rotates clockwise. Contrary to the above situation, the external resistance of the liquid increases, thereby increasing the rotational resistance of the rotor. Based on this principle, the asymmetric damping characteristics of the shock absorber can be achieved. Since the compression damping force of the shock absorber is smaller than the tensile damping force of the corresponding speed, it can better mitigate the impact and ensure that the vehicle returns to its original position quickly and stably.

[0040] like Figure 5 As shown, the present invention also provides a control method for a composite electromagnetic vibration absorber, comprising the following steps:

[0041] The control circuit of the electromagnetic shock absorber is provided with switches S1, S2, and S3, wherein when the switch S1 is closed, the switch S2 cannot be closed, and vice versa.

[0042] Step 1: Dynamically select the working mode of the motor according to the actual driving conditions. When the damping force is effective for vibration control, the motor outputs the damping force outward in a semi-active control manner, thereby reducing the energy consumption of the system. Otherwise, the motor outputs the driving force outward in an active control manner.

[0043] Since the damping force generated by the rotor motor 4 is proportional to the equivalent current in the internal coil, and the equivalent current is proportional to the motor speed and the circuit resistance, the output damping force of the motor can be obtained as expression (1):

[0044] T e =k i ·i

[0045] F=-r g ·Te

[0046]

[0047] Among them, T e is the resistance torque of the motor, k i is the motor torque constant, i is the equivalent current of the motor internal coil, r g is the transmission ratio of the planetary roller screw, F is the output damping force, v is the linear motion speed at both ends of the electromagnetic shock absorber, R is the external resistance connected to the motor, and r is the internal resistance of the motor.

[0048] From expression (1), we can see that the output damping force F of the motor is always in the opposite direction to the motion speed v. Therefore, when F is equal to the control force F required by the shock absorber, des When the direction is the same, switch S1 is closed, and the output damping force of the motor is controlled by adjusting the value of the variable resistor. Conversely, when F and F des When rotating in the reverse direction, it is necessary to actively provide electrical energy to the motor so as to output driving force to the outside. At this time, switch S2 is closed, and S1 and S3 are disconnected.

[0049] Step 2: If F and the required control force F of the shock absorber des In the same direction, the maximum damping force allowed to be output by the motor under the current working condition is calculated by expression (1):

[0050]

[0051] Step three, determine whether the maximum damping force allowed to be output by the motor can meet the vibration reduction requirements. If not, power the magnetorheological damper to increase the output damping force of the system.

[0052] When F max Greater than F des When the control force required by the shock absorber can be provided by the motor, there is no need to power the magnetorheological damper. At this time, switch S2 is closed, S1 and S3 are disconnected.

[0053] On the contrary, switches S2 and S3 are closed, S1 is open, the motor outputs the maximum damping value, and the damping force required by the magnetorheological damper is:

[0054] F mr =F des -F max (3)

[0055] Step 4: Determine whether the motor system fails based on the current in the motor circuit. When the motor fails, the control force required by the shock absorber is provided by the magnetorheological damper. The combined control of the two improves the safety of the entire shock absorption system.

[0056] After switch S2 is closed, if the actual current in the motor circuit is 0 for a long time, switch S3 is closed and S2 is disconnected, the damping force required by the magnetorheological damper is:

[0057] F mr =F des (4)

[0058] The motor has semi-active control and active control functions. The energy consumption in semi-active control is low, and the damping force of the magnetorheological damper increases the damping force output range of the system. In active control, the driving force output by the motor is controlled to maximize the handling and stability of the vehicle.

Claims

1. The present invention discloses a composite electromagnetic vibration absorber and a control method, characterized in that: The utility model comprises an upper support, a magnetorheological damper, a planetary roller screw, a rotor motor, a spring and a lower support.

2. The composite electromagnetic vibration absorber according to claim 1, characterized in that: The magnetorheological damper comprises an upper end cover, a wedge-shaped rotor, an O-type sealing ring, a stator, a coil, a retaining ring, a bearing, a magnetorheological fluid, a coil cover and a lower end cover.

3. The composite electromagnetic vibration absorber according to claim 1, characterized in that: The planetary roller screw includes a bearing, a linear bearing, a screw nut, a clamping ring, a retaining frame, a roller, a screw, a cylinder body and a cover plate arranged inside the planetary roller screw.

4. The planetary roller screw according to claim 3, characterized in that: The lead screw is connected to the lower support, a linear bearing is installed on the cylinder body, the linear bearing cooperates with the lead screw, and the cylinder body is connected to the magnetorheological damper.

5. The composite electromagnetic vibration absorber according to claim 1, characterized in that: A spring is arranged between the lower support and the planetary roller screw cylinder body.

6. The composite electromagnetic vibration absorber according to claim 1, characterized in that: The motor rotor is installed on the lead screw nut, and the motor stator is installed on the cylinder body.

7. The magnetorheological damper according to claim 2, characterized in that: The upper end cover of the magnetorheological damper is connected to the upper support.

8. The magnetorheological damper according to claim 2, characterized in that: The wedge-shaped rotor is a hollow shaft, and a keyway is arranged inside the rotor for connecting the lead screw nut. A positioning shoulder is arranged on the rotor for installing a retaining ring.

9. The magnetorheological damper according to claim 2, characterized in that: The stator is provided with a coil installation groove, and the cylinder body is provided with a wire outlet groove.

10. The magnetorheological damper according to claim 2 can output asymmetric damping, characterized in that: The rotor is provided with a wedge-shaped structure.

11. The composite electromagnetic vibration absorber according to claim 1, characterized in that: The lead screw converts the linear motion between the upper and lower supports into the rotational motion of the lead screw nut, the magnetorheological damper rotor and the motor rotor, and generates the motion resistance of the lead screw nut through the magnetorheological damper and the motor to achieve vibration reduction.

12. A control method for a combined motor and a magnetorheological damper, characterized in that: The following steps are involved: Step 1: Dynamically select the working mode of the motor according to the actual driving conditions. When the damping force is effective for vibration control, the motor outputs the damping force to the outside, thereby reducing the energy consumption of the system. Otherwise, the motor outputs the driving force to the outside, thereby maximizing the vehicle's handling and stability. Step 2: The damping force generated by the motor is proportional to the equivalent current in the motor's internal coil, and the equivalent current is proportional to the motor speed and circuit resistance. The maximum damping force allowed to be output by the motor under the current working conditions is derived. Step three, determine whether the maximum damping force allowed to be output by the motor can meet the vibration reduction requirements. If not, power the magnetorheological damper to increase the output damping force of the system. Step 4: determine whether the motor system fails based on the current in the motor circuit. When the motor fails, the damping force required by the system is provided by the magnetorheological damper.

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