Coaxial Magnetic Coupling

Coaxial magnetic coupling is used in seal-less magnetic driven pumps to transmit torque to an impeller. A standard electric motor drives a set of permanent magnets that are mounted on a carrier or drive assembly. In turn, the magnets drive the internal rotor and provide the no-slip or synchronous capability of the torque coupling.

 

 

Fluid is moved by a centrifugal pump though the centrifugal force. Fluid is taken into the center of the impeller through the inlet connection called Suction Eye. Most centrifugal pumps prefer a positive inlet pressure to prevent Cavitation (lack of enough positive inlet pressure to prevent liquid vaporization). This fluid is then caught by the vanes of the impeller as it spins. This rotation of the fluid mechanically by the vanes “throws” the fluid to the outside of the impeller and toward the discharge port of the liquid end of the pump. This mechanical movement of the fluid creates the discharge pressure of the pump. Variables like inlet fluid supply pressure, impeller diameter, motor horsepower and closed face versus open face all affect the flow and pressure of the pump. Each of these variables can be manipulated to achieve an estimated flow and/or pressure.

 

 

A magnetic drive pump uses a balanced magnetic field to create the rotation of the fluid impeller. Unlike a traditional centrifugal pump which has a direct drive connection between impeller and motor, a mag drive pump eliminates the direct drive mechanism and replaces it with a magnetic field. External magnetic bell housing is mounted on the end of the pump shaft. This external bell is aligned on the outside of the rear casing. The pump impeller is connected to a smaller magnet assembly and rides on an internal shaft and bushing assembly. (The liquid end parts are all isolated within the fluid head of the pump without the need for a mechanical seal.) The smaller magnet assembly is mounted within the center of the magnetic field of the external bell housing. Although these two magnet assemblies are separated by a fluid barrier, the magnetic fields are aligned. When the pump motor is started the external bell housing begins to rotate. As the external bell rotates, the rotating magnetic field affects the internal impeller magnet. As the two magnets begin to turn together, the impeller begins turning and displacing fluid.

 

 

A coaxial magnetic coupling is composed of two magnet assemblies. One is the external assembly (the drive magnet) and the other is the internal assembly (the driven magnet). The external assembly is connected to a motor and the internal assembly is directly attached to the pump impeller. The magnet components of the external assembly are aligned with their counterparts in the internal assembly. When load (torque) is applied, the coupling deflects angularly and the magnets create a force of simultaneous attraction and repulsion. This force is used to transfer torque from the motor to the impeller. Mag driven pumps are therefore seal-less and hermetically closed.

 

Material Selection:

Magnet: it’s based on working temperature and corrosion-resistance requirements.

NdFeB – Temperatures up to 150°C. Corrosion protection required.

Ceramic – Temperatures up to 250°C. Corrosion protection not required.

SmCo – Temperatures up to 350°C. Corrosion protection optional.

 

Housing: normal carbon steel, stainless steel(304, 316, 416 etc.), nickel super alloys (Inconel, Hastelloy, Monel, etc.)

 

Spacer sleeve: stainless steel, nickel super alloys (Inconel, Hastelloy, Monel, etc.), plastics (Nylon, Teflon, etc.), Ceramics.

 

 

 

1. Achieve zero leakage transfer of power by transforming traditional dynamic seal into static sealing.
2. Realize stable running of the device without contact as transmission of vibration can be avoided.
3. Can be applied in many harsh working environments: flammable, explosive, corrosive, damp, high-dust content, high temperature, low temperature etc.
4. Energy saving: the efficiency is improved while the load speed adjusts.
5. The torque requirement is flexible: it ranges from 100mNm. to 1000N.m, which can be customized.

 

 

We need your help to design the permanent magnetic coupling.

1. How much torque(force) would you like to transmit?
2. What’s the working speed?(velocity or RPM)
3. What’s the operating temperature range?
4. Is the containment shroud required? What pressure differential would you like the design to accommodate?
5. Dimensions reference

 

External Coupling

1). Shaft size

2). Mounting type

• Set screw and key
• Compression (threaded shaft end)
• Taper Lock (not available on all sizes)

3). Max. OD

4). Max. Length

 

Internal Coupling

1). Shaft size

2). Mounting Type

• Set Screw and key
• Compression (threaded shaft end)
• Taper Lock (not available on all sizes)

3). Max. Length

 

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