CN112161017B

CN112161017B - Quick response magneto-rheological damper

Info

Publication number: CN112161017B
Application number: CN202011006621.2A
Authority: CN
Inventors: 温明富; 刘炳杨; 牛小东
Original assignee: Shantou University
Current assignee: Shantou University
Priority date: 2020-09-22
Filing date: 2020-09-22
Publication date: 2022-08-16
Anticipated expiration: 2040-09-22
Also published as: CN112161017A

Abstract

The invention discloses a quick-response magnetorheological damper, which comprises a piston, an excitation coil, magnetorheological fluid, a piston rod, an outer cylinder barrel, an end cover, a floating piston, a guide ring and the like. The outer surface of the piston and the inner surface of the outer cylinder barrel are provided with grooves which are uniformly distributed in the radial direction and are used for inhibiting eddy current which is excited by the change of a magnetic field in a magnetic circuit; the electromagnetic coil is wound on the piston; one end of the piston rod is connected with the piston, the other end of the piston rod is connected with the external load, magnetorheological fluid is filled in the outer cylinder barrel, a damping channel is formed between the outer cylinder barrel and the piston, and the magnetorheological fluid flows between the two cavities through the damping channel. The invention relates to a magneto-rheological damper, which is characterized in that the magnetic field establishment time of the magneto-rheological damper is a key factor influencing the quick response performance of a device, and the formation of eddy current under a dynamic magnetic field is inhibited from the aspect of prolonging a skin-seeking path based on the requirement on the quick response performance of the magneto-rheological damper, namely, a groove is arranged on the surface of a related structure to inhibit an eddy current field, so that the aim of reducing the magnetic field establishment time is fulfilled, and the magneto-rheological damper has excellent quick response performance.

Description

Quick response magneto-rheological damper

Technical Field

The invention relates to a variable damping control device, in particular to a quick-response magnetorheological damper.

Background

The magneto-rheological damper has excellent magnetic control damping characteristic, has the advantages of simple mechanical structure, wide dynamic range, low power consumption, large output damping force, short response time and the like, is widely concerned in the research of the impact buffering field, and has huge application prospect in the fields of bridges, automobiles, aerospace and the like. The dynamic response performance of the magnetorheological damper is represented by response time, the shorter the response time is, the more beneficial the magnetorheological damper is to realize real-time control, the current research on the magnetorheological damper focuses on damping force, adjustable range and control algorithm, and the research on improving the quick response performance is less. The response time of the magneto-rheological damper mainly comprises magneto-rheological fluid response time, magnetic field establishment time, circuit response time and the like, wherein the key for reducing the magnetic field establishment time is to reduce the response time of devices, and the main factor for causing the longer magnetic field establishment time is that a dynamic magnetic field corresponding to a quick change signal of an excitation coil excites eddy currents on the surface of a piston and other structures to form a reverse magnetic field to hinder establishment of a source magnetic field, so that the response of the magneto-rheological fluid to the excitation signal is delayed, and the output damping force cannot be quickly responded. Suppression of eddy currents is therefore critical to reduce response time. The existing magnetorheological damper piston generally adopts a complete cylindrical structure, and when a magnetic field changes, a large eddy current can be generated on the surface of the piston to block the change of the magnetic field, so that the response speed is reduced.

Disclosure of Invention

The technical problem to be solved by the embodiment of the invention is to provide a quick-response magnetorheological damper. The magneto-rheological damper can be quickly responded.

In order to solve the technical problem, an embodiment of the invention provides a fast response magnetorheological damper, which comprises a lower end cover, a floating piston, an excitation coil, a piston rod, an outer cylinder, an upper end cover, a piston lower end cover, a guide ring, a piston upper end cover and magnetorheological fluid, wherein two ends of the outer cylinder are closed by the upper end cover and the lower end cover to form an accommodating cavity, the piston rod penetrates through the upper end cover, a radial groove is processed on the piston, the excitation coil is wound on the piston rod, and a lead is led out of the excitation coil through a through hole formed in the piston rod; the guide ring is coaxial with the piston and is assembled between the upper end cover of the piston and the lower end cover of the piston, and the upper end cover of the piston and the lower end cover of the piston are provided with liquid flow holes; the floating piston and the piston are sequentially arranged in the accommodating cavity in a sliding mode to form a compensation cavity, a first magnetorheological fluid cavity and a first magnetorheological fluid cavity, and the magnetorheological fluid is filled in the first magnetorheological fluid cavity and the first magnetorheological fluid cavity.

And damping channel gaps are formed between the inner surface of the guide ring and the outer circular surfaces of the two wings of the piston.

The groove is communicated with the upper end face, the lower end face and the outer circular face of the piston.

The embodiment of the invention has the following beneficial effects:

1. the response speed is high. The radial uniformly distributed grooves are formed in the outer circular surface of the piston and the inner circular surface of the outer cylinder barrel, so that the skin approach path of the eddy current is prolonged, the resistance is increased equivalently according to ohm law, the eddy current is reduced and restrained, and the restraint of the eddy current field means that the weakening effect on a source magnetic field is reduced, the magnetic flux acting on a damping channel is increased, and the quick response of the damper is ensured. Finite element simulation verifies that the eddy current generated by the magneto-rheological damper with the groove is reduced by one order of magnitude compared with the traditional magneto-rheological damper without the groove, the response time under the excitation of the step rising edge is reduced by 35.85%, and the response time under the excitation of the step falling edge is reduced by 53.54%. The quick-response magnetorheological damper is particularly suitable for occasions with high requirements on the response speed of a vibration damper, such as an automobile suspension, an airplane landing gear and the like.

2. Simple structure and material saving. The magneto-rheological damper with the quick response is based on the single-rod magneto-rheological damper in structural design, the radially uniformly distributed grooves are formed in the outer circular surface of the piston and the inner circular surface of the outer cylinder barrel, the structure is simple and reliable, the piston is manufactured by adopting additive manufacturing, and due to the grooves, compared with the traditional damper, the magneto-rheological damper saves materials and is more economical and practical.

Drawings

FIG. 1 is a schematic overall sectional view of the present invention;

FIG. 2 is a front view of a piston with grooves;

FIG. 3 is a top view of a piston with grooves;

FIG. 4 is a cross-sectional view of a piston with grooves;

FIG. 5 is a partial view of a fast response magnetorheological damper at an electromagnetic piston;

FIG. 6 is a top view of the piston upper end cap;

FIG. 7 is a graph of the step rising edge excitation of this example;

FIG. 8 is a graph of step-down edge excitation for this example;

FIG. 9 is a comparison of response time under step up edge excitation of this example with a conventional magnetorheological damper, with a fast response magnetorheological damper in phantom and a conventional magnetorheological damper in cross-point;

FIG. 10 is a graph comparing response time under excitation of the step-down edge of the example with a conventional MR damper, shown in phantom as a fast response MR damper and shown in cross-dot line as a conventional MR damper.

The drawings are noted below:

1-lower end cover; 2, protective gas; 3-a floating piston; 4-a first magnetorheological fluid chamber; 5-a field coil; 6-a piston rod; 7-outer cylinder; 8-a second magnetorheological fluid chamber; 9-upper end cover; 10-a compensation chamber; 11-piston lower end cover; 12-a guide ring; 13-a piston; 14-upper end cap of piston; 15-magnetorheological fluid; 16-piston central through hole; 17-a trench; 18-axial blind hole of conductor; 19-radial holes for wires; 20-an electromagnetic piston; 21-flow orifice; 22 — damping channel.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention will be described in further detail with reference to the accompanying drawings.

Referring to fig. 1, the fast response magnetorheological damper of the embodiment of the invention comprises a lower end cover 1, a floating piston 3, an excitation coil 5, a piston rod 6, an outer cylinder 7, an upper end cover 9, a piston lower end cover 11, a guide ring 12, a piston 13, a piston upper end cover 14 and magnetorheological fluid 15.

The electromagnetic piston 20 is composed of a piston 13, an excitation coil 5, a piston rod 6, an upper piston end cover 14, a lower piston end cover 11, a guide ring 12 and the like.

Two ends of the outer cylinder barrel 7 are sealed by an upper end cover 9 and a lower end cover 1 to form an accommodating cavity, wherein a round hole is processed in the center of the upper end cover, and a piston rod penetrates through the round hole; the piston is provided with a radial groove 17, a through hole 16 is formed in the center, and the magnet exciting coil 5 is wound in the middle as shown in figures 2 to 4.

As shown in fig. 5, the guide ring 12 is coaxial with the piston 13 and is assembled between the piston upper end cap 14 and the piston lower end cap 11, and the inner side of the guide ring keeps a certain distance with the outer circumferential surface of the piston side wing, so as to form a damping channel 22, and the magnetorheological fluid 15 flows in from the fluid flow hole 21 of the piston end cap and flows out through the damping channel 22. The upper end cover 14 and the lower end cover 11 of the piston are provided with liquid flow holes 21 which are uniformly distributed in the circumferential direction and are coaxially and coplanarly matched with the upper end surface and the lower end surface of the piston, as shown in figure 6.

The piston rod 6 penetrates through the piston central through hole 16 and is in interference fit with the through hole, when external load acts on one end of the piston rod 6, the piston rod and the piston move together, and resistance borne by the piston also acts on the external load on the other end of the piston rod 6, so that the transmission of motion and force is realized.

When the exciting coil 5 is energized, the piston 13, the magnetorheological fluid 15 and the outer cylinder 7 form a magnetic circuit. The magnetic flux is generated by the magnet exciting coil 5 in the middle of the piston, is transmitted to the piston side wings through the core part of the piston 13, passes through the damping channel filled with the magnetorheological fluid 15, enters the outer cylinder barrel 7, passes through the damping channel 22 through the outer cylinder barrel 7 and returns to the core part through the other side wings of the piston.

The inner circular surface of the outer cylinder barrel 7 is processed with grooves which are uniformly distributed in the radial direction, two ends of the outer cylinder barrel are respectively assembled with the upper end cover 9 and the lower end cover 1 to form a closed cavity body, the outer cylinder barrel is divided into three cavities by the floating piston 3 and the electromagnetic piston 20, a compensation cavity 10 is arranged between the lower end cover 1 and the floating piston 3, a first magnetorheological fluid cavity 4 is arranged between the floating piston 3 and the electromagnetic piston 20, the electromagnetic piston 20 and the upper end cover 9 are a second magnetorheological fluid cavity 8, the upper end cover 9, the floating piston 3 and the lower end cover 1 are all provided with sealing rings for sealing, the upper end cover 14 of the piston at the position of the electromagnetic piston 20, the guide ring 12 and the lower end cover 11 of the piston are all tightly matched with the inner wall of the outer cylinder barrel 7, and a damping channel 22 is reserved to communicate the first magnetorheological fluid cavity 4 with the second magnetorheological fluid cavity 8. The compensation cavity 10 is filled with protective gas 2 and is used for compensating pressure difference caused by the existence of the piston rod 6 in the second magnetorheological fluid cavity 8 when the damper operates.

The working process of the invention is as follows:

refer to fig. 7, fig. 8. When the exciting coil 5 is not electrified, if the piston rod 6 moves towards the lower end cover under the action of the load, the magnetorheological fluid in the first magnetorheological fluid cavity 4 is compressed and flows to the second magnetorheological fluid cavity through the damping channel 22 of the electromagnetic piston 20. At this time, no magnetic field exists in the damping channel 22, the magnetorheological fluid 15 can be regarded as Newtonian fluid, and the damping force generated by the motion of the piston is very small; if the excitation coil 5 is electrified, namely step rising edge current excitation is applied to the magnetorheological damper, and a current step response diagram refers to fig. 7, a source magnetic field excited by the excitation coil 5, the magnetorheological fluid 15 at the damping channel 22 forms a chain structure along magnetic lines under the action of the magnetic field, and the ferromagnetic particles are changed into quasi-solid from Newtonian fluid, so that the damping force borne by the electromagnetic piston 20 is increased, and the damping force is transmitted to external loads through the piston rod 6 to complete the response to the loads such as vibration; if the exciting coil is powered off after being powered on for a period of time, namely step-down edge current excitation is applied to the magnetorheological damper, a current step response graph refers to fig. 8, a source magnetic field is gradually weakened to disappear, magnetorheological fluid in the damping channel 22 is changed into Newtonian fluid from quasi-solid due to weakening of the magnetic field, and the damping force of the piston is reduced.

The quick response principle of the invention is as follows:

the piston 13 and the outer cylinder barrel 7 of the quick-response magnetorheological damper are provided with grooves 17 which are uniformly distributed in the radial direction, when the excitation coil is electrified, namely step rising edge current excitation is applied to the magnetorheological damper, for the traditional damper without grooves, magnetic flux is transmitted to the piston side wing through the piston core part, an eddy current field is inevitably excited on the surface of the piston, the eddy current field also induces a magnetic field in the opposite direction, the magnetic flux of a source magnetic field is prevented from being transmitted to a damping channel, the magnetic field of the damping channel is delayed to be established, and the response of a damping force is slowed; for the magneto-rheological damper with the groove, the groove is arranged to divide the surface of the piston according to the skin effect of the eddy current, so that the attachment path is prolonged, the extension of the attachment path is equivalent to the increase of resistance according to the ohm law, so that the eddy current is reduced, the reverse induction magnetic field of the eddy current is weakened, the source magnetic field is quickly established in the damping channel, the damping force is quickly responded, and the quick response performance is realized; when the excitation coil is powered off, namely step-down edge current excitation is applied to the magnetorheological damper, for the traditional damper without a groove, a magnetic field is suddenly reduced to excite eddy currents on the surface of a piston, the eddy currents induce a reverse magnetic field to prevent the magnetic field from weakening, and further the magnetic field at a damping channel cannot be rapidly disappeared, namely the speed of restoring the magnetorheological fluid from a solid-like body to Newtonian fluid is slowed, and the response of a damping force is slowed; for the magneto-rheological damper with the groove, the groove enables eddy current excited by magnetic field change to be greatly weakened, the magnetic field at the damping channel is rapidly subsided, the magneto-rheological fluid can be rapidly changed into Newtonian fluid after the excitation coil is powered off, and the response speed of the damping force is increased.

Referring to fig. 9 and 10, finite element simulation of the magnetorheological damper is carried out in ANSYS Maxwell, and the response time of the magnetorheological damper is calculated. The result shows that the quick response performance of the magnetorheological damper is greatly enhanced by the grooves of the piston and the outer cylinder barrel, in the embodiment, the response time is respectively reduced by 35.85% and 53.54% when compared with that of the traditional magnetorheological damper with the same specification when the magnetorheological damper is powered on and powered off, and the eddy current amount is reduced by one order of magnitude compared with that of the traditional magnetorheological damper through simulation verification.

Alternatively, in this embodiment, the number of the grooves is set to be 108, the number of the fluid holes of the upper end cover and the lower end cover of the piston is set to be 4, the upper end cover and the lower end cover of the piston are closed by welding with the outer cylinder barrel, the current peak value of the step rising edge and the current peak value of the falling edge are 2A, and the response time is less than 1ms, see fig. 7 and 8.

While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiment, it is to be understood that the invention is not to be limited to the disclosed embodiment, but on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims.

Claims

1. A quick response magneto-rheological damper is characterized by comprising a lower end cover, a floating piston, an excitation coil, a piston rod, an outer cylinder barrel, an upper end cover, a piston lower end cover, a guide ring, a piston upper end cover and magneto-rheological fluid, two ends of the outer cylinder barrel are sealed by the upper end cover and the lower end cover to form an accommodating cavity, the piston rod penetrates through the upper end cover, the inner surface of the guide ring and the outer circular surfaces of two wings of the piston form a damping channel gap, the piston and the outer cylinder barrel are both processed with grooves which are uniformly distributed in the radial direction, the device is used for reducing eddy current, so that a source magnetic field is quickly established in a damping channel, the damping force is quickly responded, the grooves are communicated with the upper end surface, the lower end surface and the outer circular surface of the piston, the number of the grooves is 108, the piston is wound with the excitation coil, and a lead is led out of the excitation coil through a through hole formed in the piston rod; the guide ring is coaxial with the piston and is assembled between the upper end cover of the piston and the lower end cover of the piston, and the upper end cover of the piston and the lower end cover of the piston are provided with liquid flow holes; the floating piston and the piston are sequentially arranged in the accommodating cavity in a sliding mode to form a compensation cavity, a first magnetorheological fluid cavity and a second magnetorheological fluid cavity, and the magnetorheological fluids are filled in the first magnetorheological fluid cavity and the second magnetorheological fluid cavity.