Electromagnetic coil, magneto-rheological shock absorber and automobile

Abstract

The invention discloses an electromagnetic coil, a magnetorheological damper and an automobile. The electromagnetic coil comprises an iron core and an excitation wire. The iron core is sleeved outside the sliding end, and a wire slot is annularly formed in the peripheral side of the iron core; the excitation wire is wound in the wire slot to form an excitation coil, and the cross section of the excitation wire is in a flat geometric shape; the magnetorheological damper comprises the electromagnetic coil and is applied to an automobile. According to the scheme, after the excitation wires are wound into the excitation coil, the gaps between the wires of each turn and the gaps between the wires outside the excitation coil and the slot wall of the wire slot are greatly reduced, under the condition that the space of the wire slot is not changed, the number of turns of the coil can be increased by using the flat excitation wires, and the utilization rate of the space in the wire slot is higher; the effective working length of the electromagnetic coil is larger, the maximum damping force of the magneto-rheological shock absorber can be improved, the electromagnetic efficiency is greatly improved, and large damping force can be generated only through small current.

Description

Technical Field

[0001] The present invention relates to the technical field of vehicle vibration damping, and particularly to an electromagnetic coil, a magnetorheological damper, and an automobile. Background Art

[0002] A magnetorheological damper is a device that uses the magnetorheological effect to adjust damping, and is widely used in fields such as mechanical vibration control, vehicle shock absorption, and bridge seismic isolation. Its working principle is to control the rheological characteristics of the magnetorheological fluid by changing the magnetic field, thereby achieving the adjustment of the damping force. The core of the magnetorheological damper is the magnetorheological fluid, which is a suspension containing magnetic particles. In the absence of a magnetic field, the magnetorheological fluid behaves like an ordinary liquid, and the particles are randomly distributed. When the electromagnetic coil is energized to generate a magnetic field, the magnetic particles in the magnetorheological fluid will align along the magnetic field direction, forming a fibrous structure, thereby increasing the viscosity and damping force of the fluid. By changing the magnitude of the current, the intensity of the magnetic field can be adjusted, and then the rheological characteristics of the magnetorheological fluid can be changed to achieve dynamic adjustment of the damping force.

[0003] In the existing magnetorheological dampers, the electromagnetic coil uses a circular wire, and a wire groove is provided on the outer periphery of the iron core. Multiple turns of circular wire are wound in the wire groove. However, after the circular wire is wound around the iron core, there will inevitably be gaps between each turn of the coil, and there will also be a gap between the coil and the iron core. This results in a low space utilization rate in the wire groove, and in a fixed wire groove space, the maximum current density that can be achieved with the circular wire structure is relatively small, which limits the performance of the magnetorheological damper. Summary of the Invention

[0004] The main object of the present invention is to propose an electromagnetic coil, a magnetorheological damper, and an automobile, aiming to improve the maximum current density of the coil to improve the performance of the magnetorheological damper.

[0005] To achieve the above object, the present invention proposes an electromagnetic coil applied to a magnetorheological damper, including:

[0006] An iron core, with a wire groove provided on the outer peripheral side of the iron core; and

[0007] An exciting wire, which is wound in the wire groove to form an exciting coil, and the cross-section of the exciting wire is in a flat geometric shape.

[0008] In some embodiments of the present invention, the cross-section of the exciting wire is rectangular, the width of the exciting wire is greater than the thickness, and the thickness direction of the exciting wire is arranged in the same direction as the radial direction of the iron core.

[0009] In some embodiments of the present invention, the ratio of the width to the thickness of the exciting wire is greater than or equal to 1.2 and less than or equal to 10.

[0010] In some embodiments of the present invention, the exciting wire is wound in multiple layers to form the exciting coil, and the ratio of the number of layers of the exciting coil to the number of turns per layer of the exciting coil is greater than or equal to 1 / 2 and less than or equal to 30.

[0011] In some embodiments of the present invention, there are at least two wire grooves, and the at least two wire grooves are arranged at intervals along the axial direction of the iron core;

[0012] At least two exciting coils are provided, and one exciting coil is wound in one wire groove.

[0013] In some embodiments of the present invention, there are two wire grooves, the widths of the (131) of the two wire grooves are b1 and b2 respectively, and the width of the outer peripheral surface of the iron core (13) in its axial direction is w, and the three satisfy the relationship: 1 / 6 ≤ (b1 + b2) / w ≤ 1 / 2.

[0014] In some embodiments of the present invention, the distances between the two axial edges on the circumferential side of the iron core and the adjacent wire grooves (131) are set as c1 and c2 respectively, the distance between the two wire grooves is e, and both c1 and c2 are not less than e / 3 and not greater than 2e / 3.

[0015] In some embodiments of the present invention, the exciting wire is an enameled wire.

[0016] The present invention also provides a magnetorheological shock absorber, including a cylinder block, a floating piston and a damping piston; wherein,

[0017] An active chamber is formed in the cylinder block;

[0018] The floating piston is slidably installed in the cylinder block and divides the active chamber into a liquid chamber and a gas chamber;

[0019] The damping piston includes a piston rod, an upper pressure plate, a lower pressure plate, a piston outer sleeve and the electromagnetic coil;

[0020] The two ends of the piston rod are a sliding end and a connecting end respectively. The sliding end penetrates through the liquid chamber, the connecting end is exposed outside the cylinder block, and the iron core is connected to the sliding end;

[0021] The upper pressure plate and the lower pressure plate are respectively connected to the opposite sides of the iron core in the axial direction. The piston outer sleeve is sleeved outside the iron core, and a through damping channel is formed between the upper pressure plate, the lower pressure plate and the iron core.

[0022] The present invention also provides an automobile, including the magnetorheological shock absorber.

[0023] In the technical solution of the present invention, the electromagnetic coil uses a flat excitation wire. After the excitation wire is wound into an excitation coil, the gap between each turn of the wire and the gap between the outer wire of the excitation coil and the groove wall of the wire groove are greatly reduced. Without changing the space of the wire groove, using a flat excitation wire can increase the number of turns of the coil, improve the space utilization rate in the wire groove, increase the effective working length of the electromagnetic coil, improve the maximum damping force of the magnetorheological shock absorber, greatly improve the electromagnetic efficiency, and only a small current is required to generate a large damping force. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the following drawings are only some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can be obtained based on the structures shown in these drawings.

[0025] Figure 1 FIG. is a schematic structural diagram of an embodiment of a magnetorheological shock absorber provided by the present invention;

[0026] Figure 2 FIG. is a schematic structural diagram of a piston rod, an iron core and an excitation coil in the solution of the present invention;

[0027] Figure 3 is Figure 2 an enlarged view of part A in;

[0028] Figure 4 FIG. is another schematic structural diagram of a piston rod, an iron core and an excitation coil in the solution of the present invention.

[0029] Explanation of the reference numerals in the drawings:

[0030] 100, magnetorheological shock absorber; 10, electromagnetic coil; 11, cylinder block; 111, movable chamber; 1111, liquid chamber; 1112, gas chamber; 12, piston rod; 121, sliding end; 122, connecting end; 123, rod body; 124, fixing bolt; 1241, head; 1242, rod part; 13, iron core; 131, wire groove; 132, assembly through hole; 133, limiting ring; 14, excitation wire; 140, excitation coil; 15, upper pressure plate; 16, lower pressure plate; 17, piston outer sleeve; 20, floating piston; 30, damping channel.

[0031] The realization of the purpose, functional characteristics and advantages of the present invention will be further described with reference to the embodiments and the drawings. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0032] The following will clearly and completely describe the technical solutions in the embodiments of the present invention with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts belong to the scope of protection of the present invention.

[0033] It should be noted that if there are directional indications (such as up, down, left, right, front, back,...) involved in the embodiments of the present invention, the directional indications are only used to explain the relative positional relationship and movement conditions between components in a specific posture. If the specific posture changes, the directional indications will also change accordingly.

[0034] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only for descriptive purposes and cannot be understood as indicating or implying their relative importance or implicitly indicating the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include at least one such feature. In addition, if "and / or" or "and / or" appears throughout the text, its meaning includes three parallel scenarios. Taking "A and / or B" as an example, it includes scenario A, or scenario B, or the scenario where A and B are satisfied simultaneously. In addition, the technical solutions between various embodiments can be combined with each other, but it must be based on the fact that those of ordinary skill in the art can implement them. When the combination of technical solutions results in contradictions or cannot be implemented, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0035] Please refer to Figures 1 to 4, the present invention provides an electromagnetic coil 10 and a magnetorheological damper 100. The magnetorheological damper 100 includes: a cylinder block 11, a floating piston 20 and a damping piston; wherein, an active chamber 111 is formed in the cylinder block 11; the floating piston 20 is slidably installed in the cylinder block 11 and divides the active chamber 111 into a liquid chamber 1111 and a gas chamber 1112; the damping piston includes a piston rod 12, an upper pressure plate 15, a lower pressure plate 16, a piston outer sleeve 17 and an electromagnetic coil 10; the electromagnetic coil 10 includes an iron core 13 and an exciting wire 14; the iron core 13 is sleeved outside the sliding end 121, and a wire groove 131 is annularly arranged on the outer peripheral side of the iron core 13; the exciting wire 14 is wound in the wire groove 131 to form an exciting coil 140, and the cross section of the exciting wire 14 is in a flat geometric shape; both ends of the piston rod 12 are a sliding end 121 and a connecting end 122 respectively, the sliding end 121 penetrates into the liquid chamber 1111, the connecting end 122 is exposed outside the cylinder block 11, and the iron core 13 is connected to the sliding end 121; the upper pressure plate 15 and the lower pressure plate 16 are respectively connected to opposite sides of the iron core 13 in the axial direction, and a through damping channel 30 is formed between the piston outer sleeve 17 sleeved outside the iron core 13, the upper pressure plate 15, the lower pressure plate 16 and the iron core 13.

[0036] In the technical solution of the present invention, the electromagnetic coil 10 adopts a flat exciting wire 14. After the exciting wire 14 is wound into the exciting coil 140, the gap between each turn of the wire and the gap between the outer wire of the exciting coil 140 and the groove wall of the wire groove 131 are greatly reduced. Without changing the space of the wire groove 131, using the flat exciting wire 14 can increase the number of coil turns, the space utilization rate in the wire groove 131 is higher, the effective working length of the electromagnetic coil is larger, the maximum damping force of the magnetorheological damper 100 can be improved, the electromagnetic efficiency is greatly improved, and only a smaller current is required to generate a larger damping force. When the electromagnetic coil 10 works, the viscosity of the surrounding magnetorheological fluid increases. When the piston rod 12 is pressed and moves, the magnetorheological fluid generates a damping force through the damping channel 30. The settings of the upper pressure plate 15 and the lower pressure plate 16 can not only protect the coil and the iron core 13, but also facilitate the assembly of the piston outer sleeve 17. There is high-pressure gas in the gas chamber 1112 to provide elastic support, and by adjusting the pressure of nitrogen in the gas chamber 1112, the damping characteristics of the damper can be changed.

[0037] The structural shape of the above cylinder block 11 is generally a cylindrical shape with a relatively simple structure. The specific structure of the cylinder block 11 can be appropriately adjusted based on the cylindrical cylinder block 11 according to the actual situation, and no limitation is made here. The cross-section of the above exciting wire 14 is in a flat geometric shape. Here, the flat geometric shape means that the width of the exciting wire 14 is greater than the thickness of the exciting wire 14. Specifically, it can be rectangular, oval, etc. In some embodiments of the present invention, both sides in the thickness direction of the exciting wire 14 are flat surfaces, and both sides in the width direction of the exciting wire 14 are arc surfaces, so that the cross-section is in a capsule shape. Considering that when the exciting wire 14 is wound, compressive stress is generated in the inner part of the wire in the radial direction of the iron core 13, and tensile stress is generated in the outer part, resulting in uneven stress inside the wire. Therefore, when the flat exciting wire 14 is wound, generally the thickness direction of the exciting wire 14 is arranged in the same direction as the radial direction of the iron core 13 for winding to avoid the above problems. If the width direction of the exciting wire 14 is arranged in the same direction as the radial direction of the iron core 13 for winding, the exciting wire 14 can be arranged in a circular ring shape, so that the outer ring length of the exciting wire 14 is relatively larger than the inner ring. In this way, the shape of the exciting wire 14 is adapted to the iron core 13, thereby avoiding the problem of uneven stress.

[0038] Preferably, in some embodiments of the present invention, the cross-section of the exciting wire 14 is rectangular, the width of the exciting wire 14 is greater than the thickness, and the thickness direction of the exciting wire 14 is arranged in the same direction as the radial direction of the iron core 13. After the exciting wire 14 with a rectangular cross-section is wound, the gap between the wires and between the wire and the wall surface of the wire groove 131 is smaller, the space utilization rate in the wire groove 131 is higher, and moreover, the internal stress of the exciting wire 14 is relatively uniform after winding.

[0039] Generally, an insulating material such as rubber or plastic is wrapped outside the conductor of the exciting wire 14. When the ratio of the width to the thickness of the exciting wire 14 is too large, the wire is too flat. Compared with two exciting wires 14 with the same rectangular cross-sectional area, the cross-sectional area of the insulating material wrapped outside the flatter exciting wire 14 is larger and occupies more space. Therefore, in some embodiments of the present invention, the ratio of the width to the thickness of the exciting wire 14 is greater than or equal to 1.2 and less than or equal to 10. Specifically, it can be 1.2, 1.5, 1.8, 2, 2.2, 2.5, 2.8, 3, 5, 6, 8, 10, etc. This avoids the problem that the exciting wire 14 is too flat, which in turn causes the overall external insulating material to occupy more space in the wire groove 131.

[0040] The exciting wire 14 generally adopts a multi-layer winding method. Of course, it can also adopt a single-layer winding. Preferably, in some embodiments of the present invention, the exciting wire 14 is wound in multiple layers to form the exciting coil 140. The ratio of the number of layers of the exciting coil 140 to the number of turns per layer of the exciting coil 140 is greater than or equal to 1 / 2 and less than or equal to 30. Specifically, it can be 1 / 2, 2 / 3, 1, 2, 3, 5, 7, 8, 10, 12, 15, 20, 25, 30, etc. Multi-layer winding can significantly increase the inductance value of the coil, thereby improving the electromagnetic performance of the exciting coil 140. Specifically refer to Figure 3 , Figure 3 is a schematic enlarged structure diagram of the piston rod 12, the iron core 13 and the exciting coil 140 in the solution of the present invention. Among them, the single-row exciting wire 14 corresponds to one layer in the exciting coil 140. It can be understood that for the magnetorheological shock absorber 100, this can enhance the magnetic field strength and improve the damping force of the shock absorber. In addition, by setting the ratio of the number of layers of the exciting coil 140 to the number of turns per layer of the exciting coil 140 within a reasonable range, it is possible to avoid unreasonable coil shape and turn distribution, which may cause instability of the inductance and the problem of inductance value fluctuation.

[0041] The wire groove 131 and the exciting coil 140 can be provided with only one group. Preferably, in some embodiments of the present invention, there are at least two wire grooves 131, and the at least two wire grooves 131 are arranged at intervals along the axial direction of the iron core 13; there are at least two exciting coils 140, and one exciting coil 140 is wound in one wire groove 131. By providing a plurality of wire grooves 131 on the iron core 13 and winding a plurality of exciting coils 140, the magnetic field strength can be significantly enhanced. The magnetic fields generated by each exciting coil 140 are superimposed on each other, thereby increasing the yield stress of the magnetorheological fluid and enhancing the damping effect of the magnetorheological shock absorber 100. Moreover, the plurality of exciting coils 140 are arranged at intervals along the axial direction of the iron core 13, which can make the magnetic field distribution more uniform in the axial direction of the iron core 13, thereby improving the stability of the magnetorheological shock absorber 100.

[0042] Considering that the iron core 13 has the phenomenon of magnetic saturation and there is a limit of magnetic flux per unit area, there is an association between the outer surface area of the iron core 13 and the upper limit of the magnetic induction intensity. When the outer surface area of the iron core 13 is small, it is easier to reach the magnetic saturation state. At this time, increasing the current of the exciting coil 140 has an insufficient effect on the improvement of the magnetic induction intensity. Therefore, in order to avoid the above problems, please refer to Figure 4, in some embodiments of the present invention, there are two wire grooves, the widths of the two wire grooves are b1 and b2 respectively, and the width of the outer peripheral surface of the iron core 13 in its axial direction is w. The three satisfy the relationship: 1 / 6 ≤ (b1 + b2) / w ≤ 1 / 2. Specifically, the value of n·b / w can be set to 1 / 6, 1 / 5, 2 / 5, 1 / 4, 1 / 3, 1 / 2, etc., and is set according to specific circumstances. Through the above solution, on the basis of ensuring a relatively uniform magnetic field distribution, it is ensured that the area of the iron core 13 leaking outside the excitation coil 140 is not too small, and it is also ensured that the wire groove 131 has enough space to accommodate the excitation coil 140, so that the upper limit of the magnetic induction intensity generated by the excitation coil 140 and the iron core 13 as a whole is relatively high.

[0043] Furthermore, in order to ensure that the magnetic induction intensities of the various parts of the iron core 13 leaking outside are uniform and avoid the problem that some parts of the iron core 13 are magnetically saturated while other parts have less magnetic flux, in some embodiments of the present invention, the distances between the two axial edges of the circumferential side of the iron core 13 and the adjacent wire grooves 131 are c1 and c2 respectively, the distance between the two wire grooves 131 is set to e, and both c1 and c2 are not less than e / 3 and not greater than 2e / 3. Specifically, the values of c1 / e and c2 / e can be set to 1 / 3, 2 / 5, 1 / 2, 2 / 3, etc. In this way, the parts between the two axial edges of the circumferential side of the iron core 13 and the adjacent two wire grooves 131 are arranged more uniformly, so as to ensure that the magnetic field is more uniformly distributed in the axial direction of the iron core 13.

[0044] In some embodiments of the present invention, the iron core 13 is axially provided with an assembly through hole for assembling the piston rod 12, and the distance between the wire groove 131 and the assembly through hole is not less than 1 / 10 of the radius of the iron core 131. Specifically, it can be set to 1 / 10, 1 / 8, 1 / 6, 1 / 5, 1 / 4, 1 / 3, 1 / 2, etc. of the radius of the iron core 13. To ensure that there is enough magnetic circuit area between the assembly through hole and the wire groove 131 and avoid premature magnetic saturation of this part. Furthermore, considering the situation where the apertures of the assembly through holes 132 are different, resulting in unequal distances between the two wire grooves 131 and the assembly through hole in the radial direction of the iron core 13, in order to ensure sufficient magnetic circuit area and uniform magnetic induction intensity of the electromagnetic coil 10, the groove depth of the wire groove 131 with a smaller radial distance from the assembly through hole in the iron core 13 can be less than that of the other wire groove 131, and its groove width can be greater than that of the other wire groove 131, so that the current cross-sectional areas of the excitation coils in the two wire grooves are close, so that both sufficient magnetic circuit area can be ensured and the magnetic induction intensity of the electromagnetic coil 10 can be relatively uniform.

[0045] In some embodiments of the present invention, the excitation wire 14 is an enameled wire. The enameled wire has good insulation performance to prevent short circuits and electric leakage, ensuring the normal operation of the excitation coil 140. The enameled wire has good flexibility and can be easily wound into coils of various shapes to adapt to different electromagnetic device structures.

[0046] There are various specific ways to install the iron core 13 on the piston rod 12. The two can adopt interference fit or threaded connection, etc. Preferably, in some embodiments of the present invention, the piston rod 12 includes a rod body 123 and a fixing bolt 124. An assembly through hole is provided in the iron core 13, and a limiting ring is provided on the wall surface of the assembly through hole. One end of the rod body 123 is a sliding end 121, and a threaded hole is provided on the end face of the sliding end 121. The sliding end 121 extends into one end of the assembly through hole and abuts against one side of the limiting ring; the fixing bolt 124 includes a connected head 1241 and a rod portion 1242. The rod portion 1242 extends into the assembly through hole and is threadedly connected to the threaded hole, and the head 1241 is limited to the other side of the limiting ring. Through the double fixation of threaded connection and the limiting ring, the connection between the piston rod 12 and the iron core 13 is ensured to be firm and reliable. This design can effectively prevent the piston rod 12 from loosening due to vibration or impact during operation, improving the overall stability of the shock absorber. It simplifies the assembly process of the piston rod 12 and the iron core 13. Through the fixation of threaded connection and the limiting ring, the assembly can be completed quickly and accurately, improving production efficiency.

[0047] Continue to refer to Figure 1 and Figure 4 , taking the electromagnetic coil 10 provided with two wire grooves 131 as an example, the widths of the two wire grooves 131 are b1 and b2 respectively. According to the flat plate model damping force calculation formula:

[0048]

[0049] In the formula: l 1 is the effective length of the piston damping channel 30, l 1 = c1 + e + c2, mm; l 2 is the total width of all wire grooves 131, l 2 = b1 + b2, mm; h is the gap of the damping channel 30 between the magnetic core and the piston outer sleeve, mm; A p is the effective area of the piston, mm 2 ; D 1 is the outer diameter of the piston outer sleeve, mm; d is the diameter of the piston rod, mm; v is the moving speed of the piston relative to the cylinder block, m / s; sgn(v) is the sign function; τ y is the shear yield stress of the magnetorheological fluid under the action of the magnetic field, kPa; p 0 is the magnitude of the nitrogen gas pressure filled, kPa; η is the zero-field viscosity of the magnetorheological fluid, Pa·s.

[0050] According to this formula, without changing the overall shape of the electromagnetic coil 10, by improving the shape of the exciting wire to increase the current density of the exciting coil 140, the shear yield stress of the magnetorheological fluid under the action of the magnetic field will increase, thereby increasing the damping force. By integrating multiple solutions in the above embodiments and conducting simulation experiments on the integrated solution, and using the method of controlling variables, a comparative test is carried out on the magnetorheological damper 100 using round enameled wire and flat enameled wire. It is roughly concluded that winding the coil with flat enameled wire can increase the space utilization rate of the wire groove 131 by 10% - 20%. Under the same space, the effective working length of the electromagnetic coil can be increased by 10% - 20%, the maximum damping force can be increased by 10% - 20%, and the electromagnetic efficiency can be increased by 10% - 20%. The bandwidth of the adjustable range of the damping force is greatly increased, and at the same time, the number of coil turns is increased. A lower current can be used under the same damping force, which can greatly reduce the power consumption.

[0051] The present invention also provides an automobile, including the above-mentioned magnetorheological damper 100. The specific structure of the magnetorheological damper 100 refers to the above embodiments. Since this automobile adopts all the technical solutions of the above embodiments, it has at least all the beneficial effects brought by the technical solutions of the above embodiments, which will not be elaborated here one by one.

[0052] The above are only exemplary embodiments of the present invention, and do not limit the patent scope of the present invention. Any equivalent structural transformation made under the technical concept of the present invention by using the content of the specification and drawings of the present invention, or directly / indirectly applied in other related technical fields, is included in the patent protection scope of the present invention.

Claims

1. An electromagnetic coil (10), applied to a magnetorheological damper, characterized in that: include: An iron core (13), wherein a wire groove (131) is provided on the outer peripheral side ring of the iron core (13); as well as An excitation wire (14), the excitation wire (14) is wound in the wire slot (131) to form an excitation coil (140), and the cross section of the excitation wire (14) is in a flat geometric shape.

2. The electromagnetic coil (10) according to claim 1, characterized in that The cross section of the excitation wire (14) is rectangular, the width of the excitation wire (14) is greater than the thickness, and the thickness direction of the excitation wire (14) is arranged in the same direction as the radial direction of the iron core (13).

3. The electromagnetic coil (10) according to claim 2, characterized in that The ratio of the width to the thickness of the excitation wire (14) is greater than or equal to 1.2 and less than or equal to 10.

4. The electromagnetic coil (10) according to claim 1, characterized in that The excitation wire (14) is wound in multiple layers to form the excitation coil (140), and the ratio of the number of layers of the excitation coil (140) to the number of turns of each layer of the excitation coil (140) is greater than or equal to 1 / 2 and less than or equal to 30.

5. The electromagnetic coil (10) according to claim 1, characterized in that At least two of the wire grooves (131) are provided, and at least two of the wire grooves (131) are spaced apart along the axial direction of the iron core (13); At least two excitation coils (140) are provided, and one of the excitation coils (140) is wound in one of the wire slots (131).

6. The electromagnetic coil (10) according to claim 5, characterized in that There are two wire grooves, the widths of the two wire grooves (131) are b1 and b2 respectively, the width of the outer peripheral surface of the iron core (13) in its axial direction is w, and the three satisfy the relationship: 1 / 6≤(b1+b2) / w≤1 / 2.

7. The electromagnetic coil (10) according to claim 6, characterized in that The distances between the two edges of the circumferential side of the iron core (13) in the axial direction and the adjacent wire slots (131) are respectively set to c1 and c2, the distance between the two wire slots (131) is both e, and c1 and c2 are not less than e / 3 and not greater than 2e / 3.

8. The electromagnetic coil (10) according to any one of claims 1 to 7, characterized in that The excitation wire (14) is an enameled wire.

9. A magnetorheological damper, characterized in that: It comprises a cylinder body (11), a floating piston (20) and a damping piston; wherein: An active chamber (111) is formed in the cylinder body (11); The floating piston (20) is slidably installed in the cylinder body (11) and divides the active chamber (111) into a liquid chamber (1111) and a gas chamber (1112); The damping piston comprises a piston rod (12), an upper pressure plate (15), a lower pressure plate (16), a piston sleeve and an electromagnetic coil (10) as claimed in any one of claims 1 to 8; The two ends of the piston rod (12) are respectively a sliding end (121) and a connecting end (122); the sliding end (121) is inserted into the liquid cavity, the connecting end (122) is exposed outside the cylinder body, and the iron core (13) is connected to the sliding end; The upper pressure plate (15) and the lower pressure plate (16) are respectively connected to opposite sides of the iron core (13) in the axial direction; the piston sleeve is sleeved outside the iron core (13) and forms a through damping channel (30) between the upper pressure plate (15), the lower pressure plate (16) and the iron core (13).

10. An automobile, characterized in that: It comprises the magnetorheological damper (100) as claimed in claim 9.

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