Magnetic liquid sealing device with active control capability

Abstract

The invention discloses a magnetic liquid sealing device with active control capability, and belongs to the technical field of mechanical sealing. The main components are a left end cover, a shell, a left bearing, a left shaft sleeve, an exciting coil I, a permanent magnet, an exciting coil II, a right shaft sleeve, a right bearing, a right end cover, a rotating shaft, a pole shoe I, an O-shaped sealing ring, a pole shoe II, a pole shoe III, a pole shoe IV and magnetic liquid. An active and passive composite magnetic field control system fusing an excitation coil and a permanent magnet is designed, the mechanical property of the magnetic linkage is regulated and controlled by controlling the excitation coil to be connected with current, active control over the voltage endurance capacity and the starting torque is achieved, and the control range of parameters of the sealing device is further enlarged through regulation and control over the magnetic linkage; the problem that the pressure resistance of the sealing structure is limited due to magnetic saturation of the magnetic liquid is solved, the universality of the magnetic liquid sealing device in the comprehensive engineering field is enhanced, and the equipment design time and cost are saved.

Description

Technical Field

[0001] The invention relates to the technical field of magnetic liquid sealing, in particular to the principle and design method of a magnetic liquid sealing device with active control capability, belonging to the technical field of mechanical sealing. Background Art

[0002] Magnetic liquid sealing devices are used in aerospace, medical, chemical and other fields due to their advantages such as zero leakage, long life and low power consumption. Pressure resistance and starting torque are key working indicators of magnetic liquid sealing devices. However, most magnetic liquid sealing devices currently do not have active control capabilities and low versatility, which greatly increases the time and cost of engineering design. The development of magnetic liquid sealing devices that can be actively controlled online is one of the problems that need to be solved for the further development of magnetic liquid sealing.

[0003] The following known technical solutions exist through patent search: the patent publication number is CN 116398642A, and this patent relates to a magnetic liquid sealing device with a winding as a magnetic source. The device achieves the purpose of regulating the magnetic field at the sealing gap of the magnetic fluid seal by regulating the current passing through the winding, and solves the problems of low magnetic field strength, difficult processing, easy demagnetization and uncontrollable magnetic field of permanent magnets commonly used in magnetic fluid seals. However, this design does not add the magnetic field of the permanent magnet, and only uses the winding as the magnetic source, so that it must pass a large current under high-voltage working conditions. The winding has a large working load, and the limitation of the working current of the wire also limits its control range of voltage resistance and starting torque, and its versatility is low.

[0004] The following known technical solutions exist through patent search: the patent publication number is CN 116398640A, and this patent relates to a magnetic liquid sealing device, which also uses permanent magnets and electromagnetic coils as magnetic sources. It can adjust the magnetic field in the sealing gap by adjusting the internal current of the electromagnetic coil, thereby increasing the sealing ability of the sealing device or reducing the starting torque of the sealing device. However, controlling the magnetic flux only by adjusting the magnetic field has a problem of limited control range. The reason is that compared with the magnetic field, the mechanical strength of the magnetic flux is more sensitive to the chain length. At the same time, the magnetic liquid has a magnetic saturation problem. At this time, the function of increasing the pressure resistance by increasing the magnetic field strength cannot take effect.

[0005] Through the above search, it is found that the above technical solutions do not affect the novelty of the present invention; and the mutual combination of the above patent documents does not destroy the creativity of the present invention. Summary of the invention

[0006] In view of the above problems, the present invention discloses a magnetic liquid sealing device with active control capability, and the technical problem to be solved is: the magnetic liquid sealing device has insufficient active control capability and low versatility.

[0007] The objective of the present invention is achieved through the following technical solutions:

[0008] The present invention discloses a magnetic liquid sealing device with active control capability, which comprises a sealing positioning component and a magnetic sealing component. The sealing positioning component comprises: a left end cover (1), bolts, nuts, a housing (2), a left bearing (3), a right bearing (9), a right end cover (10), and a rotating shaft (11). The left and right bearings are preferably ball bearings. The end cover and the housing are made of non-magnetic materials, and the rotating shaft (11) is made of magnetic materials. The invention is characterized in that the magnetic sealing component comprises a left shaft sleeve (4), an excitation coil I (5), a permanent magnet (6), an excitation coil II (7), a right shaft sleeve (8), a pole shoe I (12), an O-ring (13), a pole shoe II (14), a pole shoe III (15), a pole shoe IV (16), and a magnetic liquid (17). The pole shoe I (12) is positioned by the left shaft sleeve (4) and is connected to the pole shoe II (14). The excitation coil I (5) is located in a groove formed by the pole shoe I (12) and the pole shoe II (14). A permanent magnet (6) is arranged between the pole shoe II (14) and the pole shoe III (15). The pole shoe IV (16) is positioned by the right shaft sleeve (8) and is connected to the pole shoe III (1 5), the excitation coil II (7) is located in a groove formed by the pole shoe III (15) and the pole shoe IV (16), the pole shoe is processed into a transverse trapezoidal pole tooth near the end of the rotating shaft, the gap between the end face of the pole shoe and the rotating shaft is 0.05-0.20mm, the inner side of the pole tooth is filled with magnetic liquid (17), the pole shoe I (12) and the outer ring surface of the pole shoe III (15) and the shell (2) are provided with radial holes to lead out the excitation coil wire, and sealant is added after the wire is led out, a plurality of the magnetic sealing components are installed in series and in parallel on the rotating shaft (11), and the pole shoes are provided with annular grooves for installing O-rings (13) to prevent gas leakage in the gap between the shell (2) and the pole shoes.

[0009] According to the current input to the control excitation coil, three working modes can be realized: high withstand voltage mode, normal mode, and low torque mode. The control part includes excitation coil I (5), permanent magnet (6), excitation coil II (7), DC power supply, air pressure sensor, data acquisition card, and host computer. The connection sequence is excitation coil-DC power supply, air pressure sensor-data acquisition card-host computer. In the normal mode, no current is passed through the excitation coil I (5) and the excitation coil II (7), the permanent magnet (6) generates a compressive magnetic field, the direction of the magnetic flux is tilted from the radial direction by the gas pressure, the chain length increases, and its pressure resistance partly resists the gas pressure to form a balanced relationship; in the high-pressure resistance mode, current is passed through the excitation coil I (5) and the excitation coil II (7) to generate a magnetic field in the opposite direction to the gas pressure, the magnetic field force interacts with the gas pressure, the magnetic flux returns to the neutral position, the pressure resistance is enhanced, and it can withstand higher pressure; in the low-torque mode, reverse current is passed through the excitation coil I (5) and the excitation coil II (7) to generate a magnetic field in the same direction as the gas pressure, the magnetic field force acts in the same direction as the gas pressure, the magnetic flux inclination increases, the chain length increases, the yield stress decreases, and the starting torque decreases.

[0010] Compared with the prior art, the present invention has the following beneficial effects:

[0011] 1. The present invention discloses a magnetic liquid sealing device with active control capability, and designs an active and passive composite magnetic field control system integrating an excitation coil and a permanent magnet. Different from the traditional sealing structure with a single magnetic source such as a permanent magnet or a winding, the composite magnetic field control system has a high basic magnetic field strength (provided by a permanent magnet), and the excitation coil has a small workload and a long life. It can accurately and freely regulate the magnetic field inside each part of the magnetic liquid, greatly improving the active control accuracy and range. On the other hand, it controls the direction of the magnetic field instead of the size of the magnetic field, and the problem of the magnetic liquid's magnetic saturation limiting the withstand voltage can be solved by controlling the deformation degree of the magnetic flux. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 The figure is a schematic diagram of the overall structure of a magnetic liquid sealing device with active control capability.

[0013] Wherein: 1-left end cover, 2-housing, 3-left bearing, 4-left shaft sleeve, 5-excitation coil I, 6-permanent magnet, 7-excitation coil II, 8-right shaft sleeve, 9-right bearing, 10-right end cover, 11-rotating shaft, 12-pole shoe I, 13-O-ring, 14-pole shoe II, 15-pole shoe III, 16-pole shoe IV, 17-magnetic liquid.

[0014] Figure 2 Schematic diagram of the magnetic flux morphology inside the magnetic liquid in three working modes of the sealing device of the present invention. DETAILED DESCRIPTION

[0015] In order to better illustrate the purpose and advantages of the present invention, the invention is further described below with reference to the accompanying drawings and examples.

[0016] Embodiment 1:

[0017] This embodiment is a magnetic liquid sealing device with active control capability. Figure 1 As shown, it is mainly composed of two parts: a sealing positioning component and a magnetic sealing component. The sealing positioning component includes: a left end cover (1), bolts, nuts, a housing (2), a left bearing (3), a right bearing (9), a right end cover (10), and a rotating shaft (11). The left and right bearings are preferably ball bearings. The end cover and the housing are made of non-magnetic materials, and the rotating shaft (11) is made of magnetic materials. The magnetic sealing component comprises: a left shaft sleeve (4), an excitation coil I (5), a permanent magnet (6), an excitation coil II (7), a right shaft sleeve (8), a pole shoe I (12), an O-type sealing ring (13), a pole shoe II (14), a pole shoe III (15), a pole shoe IV (16), and a magnetic liquid (17). The pole shoe I (12), the pole shoe II (14), the pole shoe III (15), and the pole shoe IV (16) are all provided with an annular groove for installing the O-type sealing ring (13) to prevent gas leakage in the gap between the shell (2) and the pole shoe. The excitation coil I (5) and the excitation coil II (7) are wound by enameled wire.

[0018] The pole shoe is processed into a transverse trapezoidal pole tooth near the end of the rotating shaft, and the gap between the end face of the pole shoe and the rotating shaft is 0.05-0.20mm.

[0019] The outer annular surfaces of the pole shoe I (12) and the pole shoe III (15) and the housing (2) are provided with radial holes to facilitate the lead-out of the exciting coil wires, and sealant is added after the lead-out wires.

[0020] The pole shoes are made of magnetic conductive material, and the left shaft sleeve (4) and the right shaft sleeve (8) are made of magnetic isolation material.

[0021] An active and passive composite magnetic field control system integrating an excitation coil and a permanent magnet is designed. The main components of the active and passive composite magnetic field control system include an excitation coil I (5), a permanent magnet (6), an excitation coil II (7), a DC power supply, an air pressure sensor, a data acquisition card, and a host computer. The connection sequence of the main components is excitation coil-DC power supply, air pressure sensor-data acquisition card-host computer. The magnitude of the DC current passed through the excitation coil is determined by an experimental method.

[0022] The magnetic liquid sealing device can realize three working modes according to the current of the exciting coil: high voltage resistance mode, normal mode and low torque mode. Figure 2As shown, in the normal mode, the direction of the magnetic flux is tilted from the radial direction by the action of gas pressure, the chain length increases, and its pressure resistance capacity partially resists the action of gas pressure to form a balanced relationship; in the high-pressure resistance mode, a current is passed through the excitation coil to generate a magnetic field in the opposite direction to the gas pressure. The magnetic field force interacts with the gas pressure, and the magnetic flux returns to the neutral position with enhanced pressure resistance, and can withstand higher pressure; in the low-torque mode, a reverse current is passed through the excitation coil to generate a magnetic field in the same direction as the gas pressure. The magnetic field force acts in the same direction as the gas pressure, the magnetic flux inclination increases, the chain length increases, the yield stress decreases, and the starting torque decreases.

[0023] Finally, it should be noted that the specific description described above further illustrates the purpose, technical solutions and beneficial effects of the invention in detail, with the aim of helping to further understand the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A magnetic liquid sealing device with active control capability, comprising a sealing positioning component and a magnetic sealing component. The sealing positioning component comprises: A left end cover (1), bolts, nuts, a housing (2), a left bearing (3), a right bearing (9), a right end cover (10), and a rotating shaft (11). The left and right bearings are preferably ball bearings. The end cover and the housing are made of non-magnetic materials, and the rotating shaft (11) is made of magnetic materials. The invention is characterized in that the magnetic sealing component comprises a left shaft sleeve (4), an excitation coil I (5), a permanent magnet (6), an excitation coil II (7), a right shaft sleeve (8), a pole shoe I (12), an O-ring (13), a pole shoe II (14), a pole shoe III (15), a pole shoe IV (16), and a magnetic liquid (17). The pole shoe I (12) is positioned by the left shaft sleeve (4) and is connected to the pole shoe II (14). The excitation coil I (5) is located in a groove formed by the pole shoe I (12) and the pole shoe II (14). A permanent magnet (6) is installed between the pole shoe II (14) and the pole shoe III (15). The pole shoe IV (16) is positioned by the right shaft sleeve (8) and is connected to the pole shoe III (1 5), the excitation coil II (7) is located in a groove formed by the pole shoe III (15) and the pole shoe IV (16), the pole shoe is processed into a transverse trapezoidal pole tooth near the end of the rotating shaft, the gap between the end face of the pole shoe and the rotating shaft is 0.05-0.20mm, the inner side of the pole tooth is filled with magnetic liquid (17), the pole shoe I (12) and the outer ring surface of the pole shoe III (15) and the shell (2) are provided with radial holes to lead out the excitation coil wire, and sealant is added after the wire is led out, a plurality of the magnetic sealing components are installed in series and in parallel on the rotating shaft (11), and the pole shoes are provided with annular grooves for installing O-rings (13) to prevent gas leakage in the gap between the shell (2) and the pole shoes.

2. A magnetic liquid sealing device with active control capability according to claim 1, characterized in that : According to the current passed through the control excitation coil, three working modes can be realized: high voltage resistance mode, normal mode, and low torque mode. The control part includes excitation coil I (5), permanent magnet (6), excitation coil II (7), DC power supply, air pressure sensor, data acquisition card, and host computer. The connection sequence is excitation coil-DC power supply, air pressure sensor-data acquisition card-host computer. In the normal mode, no current is passed through the excitation coil I (5) and the excitation coil II (7), and the permanent magnet (6) generates a compressive magnetic field. The direction of the magnetic flux is tilted from the radial direction due to the air pressure, and the chain length increases. Its pressure resistance part resists the air pressure to form a balanced relationship; in the high voltage resistance mode, current is passed through the excitation coil I (5) and the excitation coil II (7) to generate a magnetic field in the opposite direction to the air pressure. The magnetic field force interacts with the gas pressure, and the magnetic flux returns to the neutral position. The pressure resistance is enhanced and can withstand higher pressures; In the low torque mode, reverse current is passed through the excitation coil I (5) and the excitation coil II (7) to generate a magnetic field in the same direction as the gas pressure. The magnetic field force acts in the same direction as the gas pressure, the magnetic flux inclination increases, the chain length increases, the yield stress decreases, and the starting torque decreases.

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