Pump for liquid chromatograph

Abstract

A pump device is realized, which accurately detects a flow rate of a pump, performs real-time control of the flow rate, and thus can suppress a flow rate error caused by occurrence of pulsation. Control of a pump rotation speed by a pressure sensor has low responsiveness in a low pressure region, and a correlation between a pressure and a flow rate is incomplete in a high flow rate region. With this taken into consideration, a flow rate sensor 10 is disposed at an outlet port 9 of a second pump 4. A position detection sensor 14 detects a point where a first pump 3 is shifted from a suction mode to a discharge mode. Moreover, the flow rate sensor 10 detects that there is no discharge from the pump 3, and that there is discharge from the pump 4 alone. Accordingly, a controller 15 sets a rotation speed of a motor 12 to a speed double the previous speed (double the normal rotation speed). When the flow rate sensor 10 detects an increase in the flow rate at the outlet port 9 of the second pump 4, the controller 15 returns the rotation speed of the motor 12 to a normal rotation speed. The rotation speed of the motor 12 is controlled by accurate flow rate detection by the flow rate sensor 10. Thus, occurrence of pulsation can be suppressed.

1 . A pump device comprising: 
 a first piston which moves back and forth in a first pump chamber having an inlet port and an outlet port;    a second piston which moves back and forth in a second pump chamber having an inlet port and an outlet port;    a connecting pipe for connecting the outlet port of the first pump chamber to the inlet port of the second pump chamber;    an inlet side valve, connected to the inlet port of the first pump chamber, for allowing a fluid to flow into the first pump chamber, and for checking the fluid from flowing into and out of the first pump chamber;    an outlet side valve, connected to the connecting pipe, for allowing the fluid to flow into the second pump chamber from the first pump chamber through the connecting pipe, and for checking the fluid from flowing into the second pump chamber and flowing out of the first pump chamber;    piston driving means for moving the first and second pistons back and forth;    a position detection sensor for detecting a back-and-forth movement position of the first piston;    a flow rate sensor, disposed at the outlet port of the second pump chamber, for detecting a flow rate of the fluid flowing out of the outlet port; and    control means for controlling a speed of driving the first and second pistons by the piston driving means, based on the back-and-forth movement position of the first piston, which is detected by the position detection sensor, and the flow rate of the fluid flowing out of the outlet port of the second pump chamber, which is detected by the flow rate sensor.    
   
   
       2 . The pump device according to  claim 1 , wherein the control means 
 causes the position detection sensor to detect, that the driving means is in a first region where the fluid flows into the first pump chamber from the inlet port and the fluid flows out of the outlet port of the second pump chamber, and thus causes the first and second pistons to move at a first driving speed in the first region,    causes the position detection sensor to detect, a start point of a second region where the first pump chamber is shifted from a fluid suction mode to a discharge mode, and thus causes the first and second pistons to move at a second driving speed that is a speed double the first driving speed by controlling the driving means when the driving means is in the second region, and when it is concurrently sensed, from the flow rate of the fluid detected by the flow rate sensor, that no fluid flows out of the first pump chamber and the fluid flows out of the second pump chamber alone, and    causes the speed of driving the first and second pistons to return to the first driving speed when the flow rate sensor detects an increase in an amount of the fluid flowing out of the second pump chamber.    
   
   
       3 . The pump device according to  claim 1 , further comprising: 
 a pressure sensor disposed in the outlet port of the second pump chamber, for detecting a pressure of discharging the fluid from the outlet port,    wherein a pressure value detected by the pressure sensor is supplied to the control means.    
   
   
       4 . A pump device comprising: 
 a first piston which moves back and forth in a first pump chamber having an inlet port and an outlet port;    a second piston which moves back and forth in a second pump chamber having an inlet port and an outlet port;    a connecting pipe for connecting the outlet port of the first pump chamber to the inlet port of the second pump chamber;    an inlet side valve, connected to the inlet port of the first pump chamber, for allowing a fluid to flow into the first pump chamber, and for checking the fluid from flowing into and out of the first pump chamber;    an outlet side valve, connected to the connecting pipe, for allowing the fluid to flow into the second pump chamber from the first pump chamber through the connecting pipe, and for checking the fluid from flowing into the second pump chamber and flowing out of the first pump chamber;    piston driving means for moving the first and second pistons back and forth;    a position detection sensor for detecting a back-and-forth movement position of the first piston;    a first flow rate sensor, disposed at the outlet port of the second pump chamber, detecting a flow rate of the fluid flowing out of the outlet port;    a second flow rate sensor, connected to the connecting pipe, for detecting a flow rate of the fluid flowing inside the connecting pipe; and    control means for controlling a speed of driving the first and second pistons by the piston driving means, based on the back-and-forth movement position of the first piston, which is detected by the position detection sensor, the flow rate of the fluid flowing out of the outlet port of the second pump chamber, which is detected by the first flow rate sensor, and the flow rate of the fluid flowing inside the connecting pipe, which is detected by the second flow rate sensor.    
   
   
       5 . The pump device according to  claim 4 , wherein the control means 
 causes the position detection sensor to detect, that the driving means is in a first region where the fluid flows into the first pump chamber from the inlet port and the fluid flows out of the outlet port of the second pump chamber, and thus causes the first and second pistons to move at a first driving speed in the first region,    causes the position detection sensor to detect, a start point of a second region where the first pump chamber is shifted from a fluid suction mode to a discharge mode, and thus causes the first and second pistons to move at a second driving speed that is a speed double the first driving speed by controlling the driving means when the driving means is in the second region, and when it is concurrently sensed from the flow rate of the fluid which is detected by the first flow rate sensor, that no fluid flows out of the first pump chamber and the fluid flows out of the second pump chamber alone, and    causes the speed of driving the first and second pistons to return to the first driving speed when it is detected from the flow rate detected by the second flow rate sensor that the outlet valve is shifted from a closed state to an opened state.    
   
   
       6 . The pump device according to  claim 4 , further comprising: 
 a pressure sensor, disposed at the outlet port of the second pump chamber, for detecting a pressure of discharging the fluid from the outlet port,    wherein a pressure value detected by the pressure sensor is supplied to the control means.    
   
   
       7 . A pump device comprising: 
 a first piston which moves back and forth in a first pump chamber having an inlet port and an outlet port;    a second piston which moves back and forth in a second pump chamber having an inlet port and an outlet port;    a connecting pipe for connecting the outlet port of the first pump chamber to the inlet port of the second pump chamber;    an inlet side valve, connected to the inlet port of the first pump chamber, for allowing a fluid to flow into the first pump chamber, and for checking the fluid from flowing into and out of the first pump chamber;    an outlet side valve, connected to the connecting pipe, for allowing the fluid to flow into the second pump chamber from the first pump chamber through the connecting pipe, and for checking the fluid from flowing into the second pump chamber and flowing out of the first pump chamber;    piston driving means for moving the first and second pistons back and forth;    a position detection sensor for detecting a back-and-forth movement position of the first piston;    a flow rate sensor, disposed at the outlet port of the second pump chamber, for detecting a flow rate of the fluid flowing out of the outlet port;    an opening and closing detection sensor for detecting opened and closed states of the outlet side valve; and    control means for controlling a speed of driving the first and second pistons by the piston driving means, based on the back-and-forth movement position of the first piston, which is detected by the position detection sensor, the flow rate of the fluid flowing out of the outlet port of the second pump chamber, which is detected by the flow rate sensor, and the opened and closed states of the outlet side valve, which are detected by the opening and closing detection sensor.    
   
   
       8 . The pump device according to  claim 7 , wherein the control means 
 causes the position detection sensor to detect, that the driving means is in a first region where the fluid flows into the first pump chamber from the inlet port and the fluid flows out of the outlet port of the second pump chamber, and thus causes the first and second pistons to move at a first driving speed in the first region,    causes the position detection sensor to detect, a start point of a second region where the first pump chamber is shifted from a fluid suction mode to a discharge mode, and thus causes the first and second pistons to move at a second driving speed that is a speed double the first driving speed by controlling the driving means when the driving means is in the second region, and when it is concurrently sensed, from the flow rate of the fluid detected by the flow rate sensor, that no fluid flows out of the first pump chamber and the fluid flows out of the second pump chamber alone, and    causes the speed of driving the first and second pistons to return to the first driving speed when the opening and closing detection sensor detects that the outlet valve is shifted from the closed state to the opened state.    
   
   
       9 . The pump device according to  claim 7 , further comprising: 
 a pressure sensor, disposed at the outlet port of the second pump chamber, for detecting a pressure of discharging the fluid from the outlet port,    wherein a pressure value detected by the pressure sensor is supplied to the control means.    
   
   
       10 . The pump device according to  claim 7 , wherein the outlet side valve and the opening and closing detection sensor are integrally arranged.  
   
   
       11 . A method for driving a pump device including: a first piston which moves back and forth in a first pump chamber having an inlet port and an outlet port; a second piston which moves back and forth in a second pump chamber having an inlet port and an outlet port; a connecting pipe for connecting the outlet port of the first pump chamber to the inlet port of the second pump chamber; an inlet side valve, connected to the inlet port of the first pump chamber, for allowing a fluid to flow into the first pump chamber, and for checking the fluid from flowing into and out of the first pump chamber; an outlet side valve, connected to the connecting pipe, for allowing the fluid to flow into the second pump chamber from the first pump chamber through the connecting pipe, and for checking the fluid from flowing into the second pump chamber and flowing out of the first pump chamber; and piston driving means for moving the first and second pistons back and forth, 
 the method comprising the steps of:    detecting a first region where the fluid flows into the first pump chamber from the inlet port and the fluid flows out of the outlet port of the second pump chamber;    moving the first and second pistons at a first driving speed in the first region;    detecting a start point of a second region where the first pump chamber is shifted from a fluid suction mode to a discharge mode;    moving the first and second pistons at a second driving speed that is a speed double the first driving speed when the second region is detected, and when it is concurrently sensed from the flow rate of the fluid flowing out of the outlet port of the second pump chamber that no fluid flows out of the first pump chamber and the fluid flows out of the second pump chamber alone; and    returning the speed of driving the first and second pistons to the first driving speed upon detection of an increase in an amount of the fluid flowing out of the second pump chamber.    
   
   
       12 . A method for driving a pump device including; a first piston which moves back and forth in a first pump chamber having an inlet port and an outlet port; a second piston which moves back and forth in a second pump chamber having an inlet port and an outlet port; a connecting pipe for connecting the outlet port of the first pump chamber to the inlet port of the second pump chamber; an inlet side valve, connected to the inlet port of the first pump chamber, for allowing a fluid to flow into the first pump chamber, and for checking the fluid from flowing into and out of the first pump chamber; an outlet side valve, connected to the connecting pipe, for allowing the fluid to flow into the second pump chamber from the first pump chamber through the connecting pipe, and for checking the fluid from flowing into the second pump chamber and flowing out of the first pump chamber; and piston driving means for moving the first and second pistons back and forth, 
 the method comprising the steps of:    detecting a first region where the fluid flows into the first pump chamber from the inlet port and the fluid flows out of the outlet port of the second pump chamber;    moving the first and second pistons at a first driving speed in the first region;    detecting a start point of a second region where the first pump chamber is shifted from a fluid suction mode to a discharge mode;    moving the first and second pistons at a second driving speed that is a speed double the first driving speed when the second region is detected, and when it is concurrently sensed, from the flow rate of the fluid flowing out of the outlet port of the second pump chamber, that no fluid flows out of the first pump chamber and the fluid flows out of the second pump chamber alone; and    returning the speed of driving the first and second pistons to the first driving speed when a flow rate of the fluid flowing through the connecting pipe is detected, and when it is concurrently sensed, from the detected flow rate of the fluid flowing through the connecting pipe, that the outlet valve is shifted from a closed state to an opened state.    
   
   
       13 . A method for driving a pump device including: a first piston which moves back and forth in a first pump chamber having an inlet port and an outlet port; a second piston which moves back and forth in a second pump chamber having an inlet port and an outlet port; a connecting pipe for connecting the outlet port of the first pump chamber to the inlet port of the second pump chamber; an inlet side valve, connected to the inlet port of the first pump chamber, for allowing a fluid to flow into the first pump chamber, and for checking the fluid from flowing into and out of the first pump chamber; an outlet side valve, connected to the connecting pipe, for allowing the fluid to flow into the second pump chamber from the first pump chamber through the connecting pipe, and for checking the fluid from flowing into the second pump chamber and flowing out of the first pump chamber; and piston driving means for moving the first and second pistons back and forth, 
 the method comprising the steps of:    detecting a first region where the fluid flows into the first pump chamber from the inlet port and the fluid flows out of the outlet port of the second pump chamber;    moving the first and second pistons at a first driving speed in the first region;    detecting a start point of a second region where the first pump chamber is shifted from a fluid suction mode to a discharge mode;    moving the first and second pistons at a second driving speed that is a speed double the first driving speed when the second region is detected, and when it is concurrently sensed, from the flow rate of the fluid flowing out of the outlet port of the second pump chamber, that no fluid flows out of the first pump chamber and the fluid flows out of the second pump chamber alone; and    returning the speed of driving the first and second pistons to the first driving speed when it is sensed that the outlet valve is shifted from a closed state to an opened state.    
   
   
       14 . A liquid chromatograph apparatus comprising: 
 pump means for feeding a mobile phase;    introduction means for introducing an object to be measured into the mobile phase fed by the pump means;    a separation column for separating components to be measured from the object to be measured, which is introduced by the introduction means; and    detection means for detecting the components to be measured, which are separated by the separation column,    wherein the pump means includes    a first piston which moves back and forth in a first pump chamber having an inlet port and an outlet port,    a second piston which moves back and forth in a second pump chamber having an inlet port and an outlet port,    a connecting pipe for connecting the outlet port of the first pump chamber to the inlet port of the second pump chamber,    an inlet side valve, which is connected to the inlet port of the first pump chamber, for allowing a fluid to flow into the first pump chamber, and for checking the fluid from flowing into and out of the first pump chamber,    an outlet side valve, connected to the connecting pipe, for allowing the fluid to flow into the second pump chamber from the first pump chamber through the connecting pipe, and for checking the fluid from flowing into the second pump chamber and flowing out of the first pump chamber,    piston driving means for moving the first and second pistons back and forth,    a position detection sensor which for detecting a back-and-forth movement position of the first piston,    a flow rate sensor, disposed at the outlet port of the second pump chamber, and for detecting a flow rate of the fluid flowing out of the outlet port, and    control means for controlling a speed of driving the first and second pistons by the piston driving means, based on the back-and-forth movement position of the first piston, which is detected by the position detection sensor, and the flow rate of the fluid flowing out of the outlet port of the second pump chamber, which is detected by the flow rate sensor.    
   
   
       15 . The liquid chromatograph apparatus according to  claim 14 , wherein the control means 
 causes the position detection sensor to detect, that the driving means is in a first region where the fluid flows into the first pump chamber from the inlet port and the fluid flows out of the outlet port of the second pump chamber, and thus causes the first and second pistons to move at a first driving speed in the first region,    causes the position detection sensor to detect, a start point of a second region where the first pump chamber is shifted from a fluid suction mode to a discharge mode, and thus causes the first and second pistons to move at a second driving speed that is a speed double the first driving speed by controlling the driving means when the driving means is in the second region, and it is concurrently sensed, from the flow rate of the fluid detected by the flow rate sensor, that no fluid flows out of the first pump chamber and the fluid flows out of the second pump chamber alone, and    causes the speed of driving the first and second pistons to return to the first driving speed when the flow rate sensor detects an increase in an amount of the fluid flowing out of the second pump chamber.    
   
   
       16 . A liquid chromatograph apparatus comprising: 
 pump means for feeding a mobile phase;    introduction means for introducing an object to be measured into the mobile phase fed by the pump means;    a separation column for separating components to be measured from the object to be measured, which is introduced by the introduction means; and    detection means for detecting the components to be measured, which are separated by the separation column,    wherein the pump means includes    a first piston which moves back and forth in a first pump chamber having an inlet port and an outlet port,    a second piston which moves back and forth in a second pump chamber having an inlet port and an outlet port,    a connecting pipe for connecting the outlet port of the first pump chamber to the inlet port of the second pump chamber,    an inlet side valve, connected to the inlet port of the first pump chamber, for allowing a fluid to flow into the first pump chamber, and for checking the fluid from flowing into and out of the first pump chamber,    an outlet side valve, connected to the connecting pipe, for allowing the fluid to flow into the second pump chamber from the first pump chamber through the connecting pipe, and for checking the fluid from flowing into the second pump chamber and flowing out of the first pump chamber,    piston driving means for moving the first and second pistons back and forth,    a position detection sensor for detecting a back-and-forth movement position of the first piston,    a first flow rate sensor, disposed at the outlet port of the second pump chamber, for detecting a flow rate of the fluid flowing out of the outlet port,    a second flow rate sensor, connected to the connecting pipe, detecting a flow rate of the fluid flowing inside the connecting pipe, and    control means for controlling a speed of driving the first and second pistons by the piston driving means, based on the back-and-forth movement position of the first piston, which is detected by the position detection sensor, the flow rate of the fluid flowing out of the outlet port of the second pump chamber, which is detected by the first flow rate sensor, and the flow rate of the fluid flowing inside the connecting pipe, which is detected by the second flow rate sensor.    
   
   
       17 . The liquid chromatograph apparatus according to  claim 16 , wherein the control means 
 causes the position detection sensor to detect, that the driving means is in a first region where the fluid flows into the first pump chamber from the inlet port and the fluid flows out of the outlet port of the second pump chamber, and thus causes the first and second pistons to move at a first driving speed in the first region,    causes the position detection sensor to detect, a start point of a second region where the first pump chamber is shifted from a fluid suction mode to a discharge mode, and thus causes the first and second pistons to move at a second driving speed that is a speed double the first driving speed by controlling the driving means when the driving means is in the second region, and when it is concurrently sensed, from the flow rate of the fluid detected by the first flow rate sensor, that no fluid flows out of the first pump chamber and the fluid flows out of the second pump chamber alone, and    causes the speed of driving the first and second pistons to return to the first driving speed when it is detected from the flow rate detected by the second flow rate sensor that the outlet valve is shifted from a closed state to an opened state.    
   
   
       18 . A liquid chromatograph apparatus comprising: 
 pump means for feeding a mobile phase;    introduction means for introducing an object to be measured into the mobile phase fed by the pump means;    a separation column for separating components to be measured from the object to be measured, which is introduced by the introduction means; and    detection means for detecting the components to be measured, which are separated by the separation column,    wherein the pump means includes    a first piston which moves back and forth in a first pump chamber having an inlet port and an outlet port,    a second piston which moves back and forth in a second pump chamber having an inlet port and an outlet port,    a connecting pipe for connecting the outlet port of the first pump chamber to the inlet port of the second pump chamber,    an inlet side valve, connected to the inlet port of the first pump chamber, for allowing a fluid to flow into the first pump chamber, and for checking the fluid from flowing into and out of the first pump chamber,    an outlet side valve, connected to the connecting pipe, for allowing the fluid to flow into the second pump chamber from the first pump chamber through the connecting pipe, and for checking the fluid from flowing into the second pump chamber and flowing out of the first pump chamber,    piston driving means for moving the first and second pistons back and forth,    a position detection sensor for detecting a back-and-forth movement position of the first piston,    a flow rate sensor, disposed at the outlet port of the second pump chamber, for detecting a flow rate of the fluid flowing out of the outlet port,    an opening and closing detection sensor for detecting opened and closed states of the outlet side valve, and    control means for controlling a speed of driving the first and second pistons by the piston driving means, based on the back-and-forth movement position of the first piston, which is detected by the position detection sensor, the flow rate of the fluid flowing out of the outlet port of the second pump chamber, which is detected by the flow rate sensor, and the opened and closed states of the outlet side valve, which are detected by the opening and closing detection sensor.    
   
   
       19 . The liquid chromatograph apparatus according to  claim 18 , wherein the control means 
 causes the position detection sensor to detect, that the driving means is in a first region where the fluid flows into the first pump chamber from the inlet port and the fluid flows out of the outlet port of the second pump chamber, and thus causes the first and second pistons to move at a first driving speed in the first region,    causes the position detection sensor to detect, a start point of a second region where the first pump chamber is shifted from a fluid suction mode to a discharge mode, and thus causes the first and second pistons to move at a second driving speed that is a speed double the first driving speed by controlling the driving means when the driving means is in the second region, and when it is concurrently sensed, from the flow rate of the fluid detected by the flow rate sensor, that no fluid flows out of the first pump chamber and the fluid flows out of the second pump chamber alone, and    causes the speed of driving the first and second pistons to return to the first driving speed when the opening and closing detection sensor detects that the outlet valve is shifted from the closed state to the opened state.    
   
   
       20 . The liquid chromatograph apparatus according to  claim 14 , wherein 
 the pump means is formed of pump means for feeding two different mobile phases,    the apparatus further comprises mixing means for mixing the mobile phases fed from the two pump means, and for thus supplying the mixed mobile phases to the introduction means, and    a mixture ratio of the two different mobile phases mixed by the two pump means varies with time.