Central Vacuum Motors


Basic Vacuum Motor Designs

There are two basic designs of central vacuum motor blowers manufactured by Lamb Electric:

Thru-Flow–the vacuumed air goes through the fan system and is discharged directly over the motor windings and this air provides cooling for the motor. Typical applications are dry vacuum units.

Bypass–the vacuumed air is separated from the motor cooling air. The vacuumed air does not pass over the electrical portion of the motor. Cooling air is provided by a separate ventilation fan. Typical applications are wet/dry vacuum units where there is moisture in the vacuumed air.

Air Movement Thru Vacuum Motors

The movement of air through a vacuum motor varies with the design of the unit. Single stage motors typically have the highest air flow and lowest vacuum levels. Adding fan stages increases the vacuum capability of the unit but reduces the air flow. This is because of increased impedance to air flow through the system, the result of additional fans (rotating and stationary) through which the air must pass. The following links show the route of air through bypass and thru flow designs.

One Stage Thru-Flow

Two Stage Thru-Flow

Two Stage Thru-Flow

Three Stage Bypass

Lamb vacuum motors require adequate ventilation in order to operate properly and meet their expected life targets. Improper ventilation will cause the motor to run hot and will contribute to reduced operating life.

A minimum of 3 in2 (19.4 cm2) area should be provided for ventilation air inlet and discharge.

Cooling air should not be allowed to re-circulate

The path of cooling air in the cleaner or other appliance should not restrict the minimum areas. Otherwise, this will have an adverse effect on the unit.

Thru Flow Design: The cooling air for the thru flow motor is the vacuumed or working air. It must not be allowed to re-circulate or have any debris, dirt or moisture. This will damage to the motor and possibly cause an electrical shock that could injure or even kill someone. The air going through the motor will be quite warm. As the air is compressed, substantial heat is generated. It is further heated as it passes over the electrical portion of the motor, performing its cooling function.

Bypass Design:  Bypass vacuum motors have an independent cooling fan that provides ventilation air that does not go through the working air section of the unit. It is essential that the inlet or discharge to the cooling fan not be blocked or restricted in any way as it could have a damaging thermal effect on the motor. The housing enclosing the vacuum motor must be designed in such a manner that the discharge of the cooling and working air does not re-circulate. This will introduce heated air into the cooling system and lead to thermal problems with the motor. Bypass motors can handle moisture in the working air section of the unit.

Once dirt and debris is swept up, it goes into the dirt canister where it swirls around like a cyclone, separating the large debris from the small. The cyclone forces the large debris to fall to the bottom of the dirt can while the lighter dirt and dust is vented straight outside of your home. There are no filters to clog and you get 100% sustained cleaning power.