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Integrated pump and motor

Integrated pump and motor description/claims

This application claims the benefit of U.S. Provisional Application Ser. No. 60/793,508, filed Apr. 20, 2006.

The present invention relates generally to small pumps for moving air and other gases. The low pressure pump uses a brushless DC motor to drive a reciprocating air pump. This type of device is used in various applications including medical devices such as automatic blood pressure monitoring devices where the pump inflates the blood pressure cuff.

Small motor driven reciprocating air pumps have been widely used for a variety of application and are typically used for sampling gases or inflating blood pressure measuring cuffs in the medical device field. The availability and advent of brushless DC motors have made such pumps very controllable, reliable and safe and which has greatly increased their use in the field.

In pumps of the prior art design the pump includes a pump frame with a motor mounting aperture to receive a brushless DC motor. Motors and pump capacity are matched to the particular application. Typically the motor is positioned in the frame and retained in the frame by a setscrew or other retainer device. An eccentric crank mounted to the motor shaft couples with the “big end” of connecting rod of a piston assembly that drives the piston in the pump. Most pumps rely on a rubber membrane to position and seal the piston head in the bore of the pump. Air is admitted and exhausted from the pump through a pair of flap valves that cooperate together with the reciprocating piston to form an air moving assembly.

Even when the pumps are of modest size the piston assembly forms a dynamically unbalanced element in the construction and efforts are made in the prior art to eliminate some vibration modes from the system. The most common form of balance is a simple counterweight screw, which balances the crank. Although such a system is an advantage over an unbalanced assembly it does not permit vibration free operation of the pumps nor does it permit quiet operation.

In contrast to the existing architecture for small pumps the present invention incorporates at least a portion of the motor assembly into the frame of the pump assembly simplifying motor construction and reducing the parts count of the overall device. This form of assembly also permits more accurate location and alignment of the reciprocating assembly, which is advantageous. In addition to the integration of motor elements into the pump frame, the reciprocating piston is balanced by an eccentric balancing construction that provide better “balance” or dampening of vibration modes in the device. This counter-weighted assembly addresses vibration modes and produces a pump that is quieter and smoother in operation, which is desirable in most applications.

Throughout the figures identical numerals indicate identical structure wherein:

FIG. 1 is a perspective view of the assembled device;

FIG. 2 is an exploded view of the components of the device;

FIG. 3 is a perspective view of the motor/pump frame;

FIG. 4 is a cross section of the motor/pump frame;

FIG. 5 is a perspective view of the counterweight rotor; and,

FIG. 6 is a cross section of the completed motor/pump assembly.

• Provisional Patent
• Utility Patent

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