Metering pump device

Abstract

A metering pump device capable of performing a fixed amount of discharge with a high accuracy even if a pressure difference occurs between outflow side valves. In the metering pump device, two reciprocating pump devices are used. The end and start of the discharge period of one reciprocating pump device are overlapped with the start and end of the discharge period of the other reciprocating pump device. After the inhalation operation and before the discharge period, both the inflow side valves and the outflow side valves are closed to perform a correction operation for eliminating the pressure difference by increasing or decreasing the internal volumes of the pump chambers.

1 . A metering pump device comprising:
 a plurality of reciprocating pump devices each of which is connected with an inflow side valve and an outflow side valve on an inflow side and an outflow side;   a common discharge port which is connected with the plurality of the reciprocating pump devices through the outflow side valves; and   a control part for controlling the inflow side valves, the outflow side valves and the reciprocating pump devices;   wherein the control part sets a discharge period and a waiting period for each of the plurality of the reciprocating pump devices so as to shift timings of the discharge period and the waiting period, and a starting time and an ending time of the discharge period of one of the reciprocating pump devices are superposed on an ending time and a starting time of the discharge period of another reciprocating pump device and, after a suction operation into a pump chamber has been performed in the waiting period and before the discharge period, a correcting operation is performed in which both of the inflow side valve and the outflow side valve are closed and a volume within the pump chamber is expanded or contracted to eliminate a difference in pressure between a pressure within the pump chamber and a common discharge port side.   
     
     
         2 . The metering pump device according to  claim 1 , further comprising a common suction port which is connected with the plurality of the reciprocating pump devices through the inflow side valves. 
     
     
         3 . The metering pump device according to  claim 2 , wherein a drive source for the reciprocating pump device is a stepping motor. 
     
     
         4 . The metering pump device according to  claim 3 , wherein a variation amount of an internal volume of the pump chamber corresponding to one (1) step of the stepping motor is set to be 1/100 or less with respect to an entire internal volume of the pump chamber. 
     
     
         5 . The metering pump device according to  claim 3 , further comprising a monitoring device for directly or indirectly monitoring a difference in pressure between a pressure in an inside of the pump chamber in the reciprocating pump device and a pressure on the common discharge port side,
 wherein the control part performs the correcting operation on a basis of a monitoring result in the monitoring device when a difference in pressure exists between the pressure in the inside of the pump chamber and the pressure on the common discharge port side.   
     
     
         6 . The metering pump device according to  claim 5 , wherein the monitoring device comprises:
 a plurality of first pressure sensors for monitoring respective pressures within the pump chambers of the plurality of the reciprocating pump devices, and
 a second pressure sensor for monitoring a-the pressure on the common discharge port side, 
 wherein the difference in pressure is monitored by comparing a detection result of the first pressure sensor with a detection result of the second pressure sensor. 
   
     
     
         7 . The metering pump device according to  claim 5 , wherein
 the monitoring device comprises a plurality of pressure sensors for monitoring respective pressures within the pump chambers of the plurality of the reciprocating pump devices, and   the difference in pressure is monitored by comparing a detection result of a pressure sensor, which is disposed in the pump chamber of the reciprocating pump device in which the suction operation has been performed, with a detection result of a pressure sensor which is disposed in the pump chamber of the reciprocating pump device whose output side valve is opened.   
     
     
         8 . The metering pump device according to  claim 3 , wherein
 a number of the reciprocating pump device is two, and a control device sets an expanding speed of the pump chamber when the suction operation is performed higher than a contracting speed of the pump chamber in the discharge period.   
     
     
         9 . The metering pump device according to  claim 1 , wherein the reciprocating pump device is provided with a drive source which is one of a stepping motor and an AC synchronous motor. 
     
     
         10 . The metering pump device according to  claim 1 , wherein a drive source for the reciprocating pump device is a stepping motor, and a variation amount of an internal volume of the pump chamber corresponding to one (1) step of the stepping motor is set to be 1/100 or less with respect to an entire internal volume of the pump chamber. 
     
     
         11 . The metering pump device according to  claim 1 , further comprising a monitoring device for directly or indirectly monitoring a difference in pressure between a pressure in an inside of the pump chamber in the reciprocating pump device and a pressure on the common discharge port side,
 wherein the control part performs the correcting operation on a basis of a monitoring result in the monitoring device when a difference in pressure exists between the pressure in the inside of the pump chamber and the pressure on the common discharge port side.   
     
     
         12 . The metering pump device according to  claim 11 , wherein the monitoring device comprises:
 a plurality of first pressure sensors for monitoring respective pressures within the pump chambers of the plurality of the reciprocating pump devices, and
 a second pressure sensor for monitoring the pressure on the common discharge port side, 
 wherein the difference in pressure is monitored by comparing a detection result of the first pressure sensor with a detection result of the second pressure sensor. 
   
     
     
         13 . The metering pump device according to  claim 11 , wherein
 the monitoring device comprises a plurality of pressure sensors for monitoring respective pressures within the pump chambers of the plurality of the reciprocating pump devices, and   the difference in pressure is monitored by comparing a detection result of a pressure sensor, which is disposed in the pump chamber of the reciprocating pump device in which the suction operation has been performed, with a detection result of a pressure sensor which is disposed in the pump chamber of the reciprocating pump device whose output side valve is opened.   
     
     
         14 . The metering pump device according to  claim 1 , wherein
 a number of the reciprocating pump device is two, and   the control device sets an expanding speed of the pump chamber when the suction operation is performed higher than a contracting speed of the pump chamber in the discharge period.   
     
     
         15 . A metering pump device comprising:
 a plurality of reciprocating pump devices each of which is connected with an inflow side valve and an outflow side valve on an inflow side and an outflow side;   a common discharge port which is connected with the plurality of the reciprocating pump devices through the outflow side valves; and   pressure sensors for monitoring respective pressures within a pump chamber of the plurality of the reciprocating pump devices.   
     
     
         16 . The metering pump device according to  claim 15 , further comprising a common suction port which is connected with the plurality of the reciprocating pump devices through the inflow side valves. 
     
     
         17 . The metering pump device according to  claim 16 , wherein the reciprocating pump device is provided with a drive source which is one of a stepping motor and an AC synchronous motor.