Personal sampling pump
First Claim
1. In a personal sampling pump adapted to be worn on the person for collecting over an extended period of time a sample of atmospheric pollutants to which the pump wearer may be exposed, including a sample collector for trapping pollutants present in the air, a pump for establishing air flow through said sample collector, a motor for driving said pump and a power source for said pump;
- means for controlling said motor to maintain constant air mass flow through said collector, comprisingmotor speed sensing means producing a signal proportional to the speed of said motor;
a source of reference voltage;
an amplifier for controlling the amount of power supplied by said power source to said motor;
amplifier control means having said motor speed signal and said reference voltage as inputs and for controlling said amplifier in accordance with the difference between said inputs in a sense to cause an increase in the power supplied to said motor when said reference voltage exceeds said motor speed signal and a decrease in the power supplied to said motor when said motor speed signal exceeds said reference voltage;
means providing a motor load signal proportional to the mechanical load of said pump on said motor; and
means applying said motor load signal to said amplifier control means in such sense that an increase in said motor load signal causes an increase in the power supplied to said motor.
2 Assignments
0 Petitions
Accused Products
Abstract
A portable battery powered pump providing constant mass flow of air sample through a particular filter or vapor trap in which the pump drive motor speed is controlled by an amplifier having a reference voltage input and an inverse feedback signal related to sensed motor speed. Compensation for increased resistance to air sample flow is made by a motor current feedback signal applied to the amplifier to cause motor speed to increase with increased flow resistance.
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Citations
10 Claims
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1. In a personal sampling pump adapted to be worn on the person for collecting over an extended period of time a sample of atmospheric pollutants to which the pump wearer may be exposed, including a sample collector for trapping pollutants present in the air, a pump for establishing air flow through said sample collector, a motor for driving said pump and a power source for said pump;
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means for controlling said motor to maintain constant air mass flow through said collector, comprising motor speed sensing means producing a signal proportional to the speed of said motor; a source of reference voltage; an amplifier for controlling the amount of power supplied by said power source to said motor; amplifier control means having said motor speed signal and said reference voltage as inputs and for controlling said amplifier in accordance with the difference between said inputs in a sense to cause an increase in the power supplied to said motor when said reference voltage exceeds said motor speed signal and a decrease in the power supplied to said motor when said motor speed signal exceeds said reference voltage; means providing a motor load signal proportional to the mechanical load of said pump on said motor; and means applying said motor load signal to said amplifier control means in such sense that an increase in said motor load signal causes an increase in the power supplied to said motor. - View Dependent Claims (2, 3, 4, 5)
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6. In a personal sampling pump adapted to be worn on the person for collecting over an extended period of time a sample of atmospheric pollutants to which the pump wearer may be exposed, including a sample collector for trapping pollutants present in the air, a pump for establishing air flow through said sample collector, a motor for driving said pump and a power source for said pump;
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means for controlling said motor to maintain constant air mass flow through said collector, comprising photo optical motor speed sensing means including a light source, a photo sensitive detector positioned to detect light from said source and a light chopper coupled to said motor for interrupting light from said source to said detector at a rate proportional to the speed of said motor, said detector producing a signal having a frequency proportional to the speed of said motor; a frequency to voltage converter receiving said detector signal and producing an output voltage having a magnitude proportional to the frequency of said detector signal; a source of reference voltage; an amplifier for controlling the amount of power supplied by said power source to said motor; amplifier control means having the output of said converter and said reference voltage as inputs and for controlling said amplifier in accordance with the difference between said inputs in a sense to cause an increase in the power supplied to said motor when said reference voltage exceeds said converter output and a decrease in the power supplied to said motor when said converter output exceeds said reference voltage; means providing a motor load signal proportional to the mechanical load of said pump on said motor; and means applying said motor load signal to said amplifier control means in such sense that an increase in said motor load signal causes an increase in the power supplied to said motor. - View Dependent Claims (7, 8, 9, 10)
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Specification