US 4,913,624 A · Low pulsation displacement pump

Abstract

A low pulsation displacement pump has a pair of plungers and motor driven-cams or feed screws for reciprocating the plungers. In order to cause the pump to stably discharge a liquid so that variation in discharge due to machining errors of the plungers or the feed screws is eliminated, the pump discharge pressure is measured at each of a plurality of predetermined operative positions of the plungers before delivery of the pump from a manufacturing plant, and machining errors are obtained in accordance with the thus-measured discharge pressure. Then, the speed correction factor for the motor is calculated for each of the plurality of predetermined positions of the plungers in accordance with the thus-obtained errors to store the results of the calculation in a memory. When the pump is used, the motor is operated while the speed of the motor is compensated for at each of the plurality of predetermined positions of the plungers in accordance with the speed correction factor stored in the memory, whereby the rate of discharge of pump can be kept substantially constant by preventing speed variation of the plungers due to machining error of the cams.

Claims11

Dependent claims

A method of operating a pump of the type that includes at least one plunger and driving means for reciprocating said plunger so that a liquid is sucked and discharged by the reciprocating movements of said plunger,

said method comprising:
measuring errors in the amount of driving movement per unit of time of said driving means at each of a plurality of predetermined operative positions of said plunger;
calculating a speed correction factor of said driving means for each of said plurality of predetermined operative positions in accordance with the thus measured errors, and then storing results of the calculation in a memory;
and
operating said driving means while the speed of said driving means is adjusted at each of said plurality of predetermined positions of said plunger in accordance with said stored speed correction factor so that said speed of said plunger is compensated substantially to meet a designed value for thereby making the rate of discharge substantially constant.

2 more elements

A low pulsation displacement pump comprising:

at least one plunger;
driving means for reciprocating said plunger;
memory means which stores therein a speed correction factor of said driving means for each of a plurality of predetermined operative positions of said plunger, said speed correction factor having been calculated in accordance with errors in the amount of driving movement per unit of time of said driving means at each of said plurality of predetermined positions of said plunger;
and
control means for controlling the speed of said driving means in accordance with said speed correction factor,
said control means being operative to actuate said driving means so that the speed of said driving means is adjusted at each of said plurality of predetermined positions of said plunger in accordance with said speed correction factor stored in said memory means so that the speed of said plunger is compensated substantially to a designed value and the rate of discharge of said pump is kept substantially constant.

3 more elements

Dependencies are inferred from the claim text.

Low pulsation displacement pump

Life of this patent

Low pulsation displacement pump

Life of this patent

Abstract

Claims11