JPH02206467A - Pumping apparatus - Google Patents

Abstract

PURPOSE:To reduce the number of the mechanism elements of the title apparatus and the volume of said apparatus by using a liquid pump driven by a linear motor having a magnetic field generating means generating the moving force in a forward/rearward direction corresponding to a positive/reverse current supply direction in an electric coil. CONSTITUTION:A liquid pump 12 driven by a linear motor alternately gives high discharge pressure and low suction pressure to the operation chamber of an artificial heart through a non-compressible liquid. This operation is performed by alternately supplying positive and reverse current to the electric coil 30 of the liquid pump 12 by current supply means 33-35 equipped with current supply direction control means 43 each indicating the reversal of a current supply direction. By this method, the rising and falling of pressure at the time of the change-over from suction to discharge as well as at the time of the change-over from discharge to suction are rapid and the absorption of pressure by a hydraulic fluid is eliminated and the discharge flow amount of a liquid can be also adjusted. Therefore, an accumulator or a high and low pressure electromagnetic opening and closing valve is omitted and the number of the mechanism elements of a pumping apparatus can be reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a liquid pump in which a reciprocating member is driven by a linear motor.

(Prior art) For example, in an artificial heart, a diaphragm is housed in a working chamber inside an outer container, and the diaphragm separates the blood chamber from the working chamber, and the working chamber has high pressure (high pressure air) and low pressure (suction pressure). The blood chamber is connected to the suction port via the first check valve and communicated with the discharge port via the second check valve. When high pressure is applied to the working chamber, the diaphragm is pressurized to try to contract the blood chamber, thereby causing fluid (blood) in the blood chamber to be discharged to the discharge port via the second check valve. When the working chamber is switched to low pressure,
The diaphragm is sucked into the working chamber and attempts to expand the blood chamber, which causes fluid (blood) to be sucked into the blood chamber from the suction port via the first check valve. Therefore, by alternately applying positive and negative pressure to the working chamber of the artificial heart,
The artificial heart inhales fluid (blood) into an inlet port and expels it out an outlet port. An artificial heart is driven by alternately applying high and low pressure (air) to its working chamber.

Conventionally, this high/low pressure (air) supply is performed using an air pumping device. This pumping device includes an electric motor, an air pump driven by the electric motor, a high-pressure accumulator to which the discharge pressure of the air pump is applied, a low-pressure accumulator to which the suction pressure of the air pump is applied, and a high-pressure accumulator and a low-pressure accumulator that are connected to the air pump of an artificial heart. It consists of a high-pressure electromagnetic on-off valve and a low-pressure electromagnetic on-off valve that are selectively connected to the chamber (for example, Japanese Patent Application Laid-Open No. 58-999
67, Japanese Patent Application Laid-open No. 58-169460), by closing the low-pressure solenoid on-off valve and opening the high-pressure solenoid on-off valve, high-pressure air is supplied to the air chamber of the artificial heart, and the high-pressure solenoid on-off valve is closed. Low pressure (suction pressure) is applied to the air chamber of the artificial heart by opening the low-pressure electromagnetic opening valve.

(Problem to be solved by the invention) For example, a pumping device of this type is an electric motor.

There are many single equipment elements, including an air pump, an accumulator, and high and low pressure electromagnetic on-off valves. Also, accumulators etc. occupy a relatively large space.

The entire device is relatively large. For example, if you try to omit the accumulator and directly apply high pressure (discharge pressure)/low pressure (suction pressure) to the artificial heart using a reciprocating pump, since the working fluid air is compressible, the volumetric contraction of the working fluid and Due to expansion, the amount of air pressure rise and fall relative to the reciprocating stroke of the pump is small, and the rise in pressure when switching from suction to discharge is delayed, and the fall in pressure when switching from discharge to suction is delayed. , it is necessary to make the air pump relatively large and high output.

The invention aims at reducing the equipment elements of a pumping device and reducing the device volume.

[Structure of the invention]

(Means for Solving the Problems) The pumping device of the present invention has a reciprocating motion that reduces/enlarges a fluid space (50) that communicates with a fluid output port (15) and stores an incompressible liquid (silicone oil). Parts (18,
19), an electric coil (30) for reciprocating the reciprocating member (18, 19), and an electric coil (30) for reciprocating the reciprocating member (18, 19);
A magnetic field generating means (2) for applying a magnetic field to the electric coil (30) in a direction perpendicular to the extending direction of the electric coil (30) and generating a moving force in the reciprocating direction corresponding to the forward/reverse energization direction in the electric coil (30).
5-28), a linear motor-driven liquid pump (
12); Energizing means (33-36) for forward/reversely energizing the electric coil (30); Current detecting means (37-41) for detecting the energizing current of the electric coil (30); Integrating means (43) for integrating the applied current
; and li? energization direction control means (43) that instructs the energization means (33 to 36) to reverse the energization direction when the integral value of the integration means (43) reaches the set value (Lp);
Equipped with Note that symbols in parentheses indicate corresponding elements in the embodiments shown in the drawings and described later.

(Function) When this pumping device is used, for example, to drive the artificial heart described above, the linear motor-driven liquid pump (12) is incompressible into the working chamber of the artificial heart through its fluid volume capos 1 to (15). High pressure (discharge pressure) and low pressure (suction pressure) are applied alternately through the liquid (silicone oil). this is,
The energization means (33 to 36) alternately energizes the electric coil (30) of the liquid pump (12) in forward and reverse directions. Since the liquid pump (12) supplies incompressible working fluid to the artificial heart, the pressure rises quickly when switching from suction to ejection, and the pressure rises quickly when switching from ejection to suction. Since the flow rate is fast and there is no pressure absorption by the working fluid, the accumulator and high and low pressure electromagnetic on-off valves that are the components of conventional pumping equipment can be omitted, which means that the mechanical elements of the pumping equipment can be reduced and the volume of the equipment can be reduced. .

By the way, an artificial heart needs to be driven in synchronization with the pulsation of the biological heart to which it is connected, or set at a required cycle, and must be driven to produce the required flow rate. It is determined by the reciprocating stroke of the reciprocating body of the liquid pump (12). Therefore, when trying to adjust the discharge flow rate when using the above-mentioned liquid pump (12), a position sensor such as a linear potentiometer is coupled to the linear motor to obtain a position detection signal, and the position detection signal is referred to. When the set stroke is reached, it is conceivable to switch from discharge to suction, but since the slider of the linear potentiometer reciprocates like the reciprocating body of the liquid pump, there is a problem that its durability is low.

However, in the present invention, as described above, the current of the linear motor is integrated to obtain the amount of movement (integral value) of the reciprocating body, and when this reaches a set value (set stroke), the energizing means (33 to
36) to reverse the energization direction (that is, the direction of movement of the reciprocating body).
There is no need for a movable body such as a linear potentiometer for position feedback of the reciprocating body, and there is no problem with its durability.

Here, it will be explained that the stroke is determined by integrating the current of the linear motor. When a voltage is applied to the electric coil of a linear motor, a current flows through the electric coil according to its electric resistance value and the voltage, and the electric coil starts moving in a direction determined by the magnetic field and the direction of the current. However, when an electric coil moves in a magnetic field, an induced back electromotive force is generated to hinder the movement of the electric coil. Therefore, the current flowing through the coil is the value obtained by subtracting the current flowing due to the back electromotive force from the current determined by the voltage commanded from the control unit and the coil resistance. However, this back electromotive force is proportional to the strength of the magnetic field and the moving speed of the coil.

Therefore, if the back electromotive force and the strength of the magnetic field are known, it is possible to calculate the moving speed of the coil.

By the way, since the strength of the magnetic field is maintained approximately equal in the range in which the coil moves, the moving speed can be detected only from the back electromotive force. Therefore, by calculating the moving speed and integrating it, the stroke amount can be determined.

When the length of the coil is L (m) and the magnetic flux density of the magnetic field acting on the coil is B (T), the induced back electromotive force Vr (V)
becomes Vr=−B−L·(dX/dt). Note that (dX/dt) is the coil moving speed. Therefore, if the resistance of the coil is R (Ω), then the current due to the back electromotive force 1 (
A) is Ir=Vr/R=-B-T- (dX/d t)/R
becomes. Furthermore, if the voltage output by the energizing means (33 to 36) is V (V), the current that actually flows through the coil is
(A) becomes Ic=(V-Vr)/(R+, R37). Note that R37 is the resistance value of a coil current detection resistor (37) connected in series with the coil.

Therefore, the moving speed of the coil (dX/dt) is (dX
/dt)=(R/(BL))・(re Io
). Here, IO is the current flowing through the coil when the moving speed of the coil is zero (current value immediately before the coil starts moving). In other words, the moving speed of the coil (dX/
dt) is proportional to the value obtained by subtracting the current Ic flowing through the moving coil from the current Ic flowing during stopping. In this way, the moving speed (dx/dt) of the coil can be calculated by detecting the coil current.

By integrating this moving speed (dX/dt), the moving amount X of the coil is obtained as follows.

x=4 (R/(B-L))・(Ic-Io)・dt
That is, by detecting the coil current Ic and integrating it as shown in the above equation, the amount of movement of the coil, that is, the stroke can be determined.

Incidentally, among the proportional coefficients in the above equation, the coil resistance R depends on the temperature and therefore changes over time during operation of the linear motor. Therefore, if the stroke is calculated using the above formula with the coil resistance R constant, the calculated stroke will deviate from the actual stroke.

Therefore, in a preferred embodiment of the present invention, the coil current is detected by a resistor (37) connected in series with the coil, and the coil applied voltage (V - Ic - R37) and coil current (I c
) is calculated from the relationship (R=V/IcR37), and the stroke (X) is calculated by updating the coil resistance R in the above integral equation to this calculated value. In the embodiment of the artificial heart drive mode described later, the voltage applied to the electrical coil of the near motor during the systolic phase (ejection phase) of the artificial heart is kept constant,
During the diastolic phase (inhalation phase), the voltage is set lower than that.

Therefore, the coil speed (dX/dt) becomes the lowest when the current value is maximum during the systolic phase (exhalation phase). At this time, the resistance value R3 of the current detection resistor is calculated from the value (R+R37) obtained by dividing the output voltage Vo of the energizing means (33 to 36) by the coil current.
The value obtained by subtracting 7 is used as the coil resistance R. In this way, the current coil resistance R is calculated for each cycle of the reciprocating member (the ejection period of the artificial heart), and the coil resistance R in the above integral formula for calculating the stroke amount (X) is set to the current value. By updating, fluctuations in the stroke (flow rate of the artificial heart) due to temperature changes during operation of the linear motor (low at the start of operation, increasing as the operation time elapses) are prevented.

Other objects and features of the invention will become apparent from the following description of an embodiment with reference to one drawing.

(Embodiment) FIG. 1 shows five embodiments of the present invention coupled to an artificial heart. The artificial heart 1 houses a diaphragm 2 in a working chamber 3 in an outer container, communicates with the inner space 4 of the diaphragm 2 via a suction check valve 5, and has a discharge check valve 6. It has a known structure in which the second cannula 8 is in communication with the second cannula 8 through a
is connected to the aorta 11. The working chamber 3 of the artificial heart 1 containing the silicone oil 3 is connected to the working chamber 3 via the tube 9.
It is connected to an output port 15 of a fluid pump 12 driven by a linear motor. In Figure 1, another set of artificial hearts 10
1 is connected to a living heart. The working chamber of this artificial heart IQ 101 is connected via a tube 9 to an output port 15o1 of another fluid pump 1201.

Fluid pump 1201 has exactly the same structure and dimensions as fluid pump 12.

FIG. 2a shows an enlarged vertical section of the linear motor-driven fluid pump 12, and FIG. 2b shows the TIB-IIB of FIG. 2a.
A line cross section is shown. Referring to these figures, an end member 14 having a fluid output port 15 formed therein is secured to the ring 13 along with an outer case 16. The right end of a substantially cylindrical bellows 19 is fixed to the ring 13. A partition member 17 is fixed to the left end of the bellows 19. These end members 14. With the bellows 19 and the partition member 17,
A fluid space 50 communicating with the output port 15 is defined.

A right end of a rod 18 is fixed to the center of the partition member 17. By driving this rod 18 back and forth to the right/left, the fluid space 50 is contracted/expanded, and the output port 15
The silicone oil in the fluid space 50 is then supplied to the working chamber 3 of the artificial heart 91, and the silicone oil in the working chamber 3 is sucked into the fluid space 50 through the output port 15.

An end plate 51 of the linear motor is fixed to the left end wall of the outer case 16, and the center point of the end plate 51 is placed in between.
The right ends of the two opposing magnetic support plates 21 and 22 are fixed to the magnetic end plate 51. Support plate 21.2
The left end of 2 is fixed to another end plate 52 of magnetic material. Support plates 21.22 support between them first and second bearings 20A and 20B, through which the rod 18 passes. A permanent magnet plate 25 is fixed to the upper surface of the support plate 21, and a permanent magnet plate 26 is fixed to the lower surface of the support plate 22.

A magnetic support plate 23 is provided at the upper end of the end plates 51 and 52, and a magnetic support plate 23 is provided at the lower end of the end plates 51 and 52.
A permanent magnet plate 27 is fixed to the lower surface of the support plate 23, and a permanent magnet plate 28 is fixed to the upper surface of the support plate 24. Between the permanent magnet plates 25 and 27 and between the permanent magnet plates 26 and 28, there is a space through which the coil bobbin 29 passes, and the coil bobbin 29 is disposed therein. This coil bobbin 29 is attached to the permanent magnet plate 25. Support plate 21° rod 18. A support plate 22 and a permanent magnet plate 26 penetrate therethrough. An electric coil 30 is wound around the coil bobbin 29. Moreover, as shown in FIG. 2b, this coil bobbin 29 is integrated with an arm 29A that passes through the gap between the support plates 21 and 22, and the rod 18 is fixed to this arm 29A. Therefore, the coil bobbin 29
moves to the right and left, the rod 18 moves to the right and left, the partition member 17 is driven right and left, the fluid space 50 contracts/expands, and the silicone oil in the fluid space 50 is released from the output port 15 to operate the artificial heart ffa 1. The air in the working chamber 3 is supplied to the fluid space 5 through the output port 15.
Inhaled to 0.

The permanent magnet plate 25 is uniformly permanently magnetized so that the upper surface becomes the N pole and the lower surface becomes the S pole, and the permanent magnet plate 27 is
It is uniformly permanently magnetized so that the upper surface is N t4 and the lower surface is S pole, and in the space between permanent magnet plates 25 and 27, that is, the space in which the electric coil 30 moves, A substantially uniform magnetic field (parallel magnetic field) is formed, with the north pole being the south pole and the permanent magnet plate 27 side being the south pole. The magnetic flux is: the upper surface of the permanent magnet plate 25 - the lower surface of the permanent magnet plate 27 - the upper surface of the permanent magnet plate 27 - the one end plate 51, 52 of the support plate 23 - the support plate 21
- The lower surface of the permanent magnet plate 25 - The upper surface of the permanent magnet plate 25.

The permanent magnet plate 26 is uniformly permanently magnetized so that the lower surface becomes the N pole and the upper surface becomes the S pole.
It is uniformly permanently magnetized so that the upper surface becomes the S pole and the lower surface becomes the N pole, and the space between the permanent magnet plates 26 and 28, that is, the space where the electric coil 30 moves, is
A substantially uniform magnetic field is formed with the north pole on the side and the south pole on the permanent magnet plate 28 side. The magnetic flux is: the lower surface of the permanent magnet plate 26 - the upper surface of the permanent magnet plate 28 - the lower surface of the permanent magnet plate 28 - the support plate 24 one end plate 51.52 - the support plate 22 - the permanent magnet plate 26
It flows along a path from the upper surface to the lower surface of the permanent magnet plate 26.

Now, if a current (positive direction current) flows through the electric coil 30 between the permanent magnets 25 and 27 in the direction of passing from the front to the back of the paper in Figure 2a, then according to Fleming's left hand rule, the electric current An electromagnetic force directed to the right acts on the portion of the coil 3o between the permanent magnets 25 and 27 and between the permanent magnets 26 and 28, causing the electric coil 30, that is, the coil bobbin 29 to move to the right in FIG. 2a. The rod 18 is moved to the right (discharge). When a current in the opposite direction to the above (reverse direction current) flows through the electric coil 30, the coil bobbin 29
moves to the left and the rod 18 is driven to the left (inhalation)
.

The iU air coil 30 is connected to the motor driver 31. FIG. 3 shows the configuration of the motor driver 31 and the pumping controller 42 that controls the energization of the motor driver 31. Referring to FIG. 3, the electric coil 3 of the linear motor described above
0 is connected to the power supply contact of the 1 energization direction switching relay 33. The coil of the relay 33 is connected to a relay driver (amplifier) 34. When the coil of the relay 33 is not energized (the signal S to the relay driver 34 is at low level 0=L), the relay contact is positioned as shown in FIG. is positive direction energization (discharge). When the signal S becomes high level 1=H, the relay driver 34 energizes the coil of the relay 33,
The relay contact is switched, and the electric coil 30 is energized in the reverse direction (suction).

The electric coil 30 has a constant voltage coil driver (a constant voltage amplifier that outputs a voltage at a specified level) 35 that connects the D/
A voltage at a level corresponding to the output signal of the A converter 36 is applied. A resistor 37 with a low resistance value for current detection is connected to the electric coil 30 via a relay 33, and the voltage of this resistor 37 (coil current signal: current I of the electric coil 30) is connected to the electric coil 30 via a relay 33.
(a voltage proportional to c) is applied to an amplifier 39 through a low-pass filter 38, where the level is calibrated and applied to a hold circuit 40. The holding voltage of the hold circuit 40 is converted into digital data by the A/D converter 41, and the microprocessor (
(hereinafter referred to as CPU) 43. In addition, relay 3
3 switching signal S and data V specifying the voltage to be applied to the electric coil 30. is given to the motor driver 31 by the CPU 43.

The pumping controller 42 includes a CPU 43 and an operation board 42. Although not shown, the operation board 42 is equipped with a large number of key switches for instructing adjustment of various drive parameters, and various indicators for displaying the values of each parameter at that time. The adjustable parameters include the force (positive and reverse current values) for driving the driving liquid (silicon oil) applied to the artificial heart Ika1, the period for applying positive pressure, and the pulsation cycle. Also, in this example,
The timing for applying positive pressure and the timing for applying negative pressure to the artificial heart 1 are generated within the CPU 43 (internal synchronization), or synchronization signals are applied from outside ("external synchronization" in FIG. 3). It is possible to switch whether to synchronize with The configuration of the motor driver 3101 shown in FIG. 1 is also the same as that of the motor driver 31, and the configuration of the pumping controller 4201 is also the same as that of the pumping controller 42.

FIG. 4 shows an overview of the control operation of the CPU 43 shown in FIG.
Do 2). In other words, the contents of the internal memory are cleared, the output signal level at the specified time is output to the output port, and the predetermined initial value (standard value) is set in the area (register) in which various parameter values of the internal memory are written. (write).

In this initialization (2), the standard value Vps is written in the register Vp in which the voltage data VP applied to the electric coil 30 during the discharge period is written, and the standard value Vps is written in the register LP in which the discharge period stroke (discharge period) data Lp is written. Lps, the standard value Vns to the register Vn which writes the voltage data Vn applied to the electric coil 30 during the inhalation period, the standard value Tcs to the register Tc which writes the pulse cycle data Tc in the case of internal synchronous drive, and the electric coil 30. Coefficient data A (A=R
/Rs; R is the instantaneous coil resistance, Rs is the coil resistance at standard temperature). The standard value As (As
= 1) above the current value immediately before the electric coil 30 starts moving. (The maximum current value at which the coil 30 remains stopped when the energization level is gradually increased) is written in the register I. The standard value Ios is set to R/(B - L) in the stroke calculation formula.
Standard value Ds=R is written in register D to which data D representing
s/(BL).

Further, the standard value R37s is written in the register R37 in which the resistance value R37 of the coil current detection resistor 37 is written.

After completing the initialization (2), the CPU 43
The operation board 4 reads the input operations of the various key switches provided on the board, changes the setting values (contents of the above-mentioned various registers) according to the input, and changes the setting values of various parameters at that time.
2 (4).

When the start key switch on the operation board 42 is operated, the CPU 43 sets the content of the register P for counting the number of beats to 1 (6), and first converts the voltage Vp in the ejection period (the content of the register Vp) to the D/A converter. 36 (at this point, it is outputting S20 due to initialization), but if the output is instantaneously switched from 0 to VP, the transient rush current to the electric coil 30 will be too large, so Increase the output data VO by a predetermined step every time the time elapses,
At the end of the transient entry period t1, the output data vo is set to VP (7). As a result, the voltage VP during the exhalation phase is applied from the coil driver 35 to the electric coil 30, and a positive current flows through the electric coil 30 (the fluid space 50 in FIG. 2a is reduced and high voltage is applied to the artificial heart 1). .

The CPU 43 outputs the ejection phase voltage Vp (7).

In order to take the timing of the minute time dt, start the timer dt (8), wait for the time to elapse (9), and when the time elapses, read the current value Ic of the electric coil 30 (
10). This first instructs the hold circuit 40 to hold to hold the current detection signal at that point, instructs the A/D converter 41 to perform digital conversion, and reads the digital data output by the A/D converter 41. Do it by doing this. The read current value data Ic is stored in register RIc.
write to.

Next, the CPU 43 calculates the amount of movement D・(Rlc Io)・A−dt of the electric coil 30 (rod 18) during dt, adds it to the contents of the register X (integrates it),
The added sum is updated and written to the register X (11). That is, the amount of movement of the rod 18 is calculated, and the contents of register X are updated to the calculated value.

Note that D, Rlc, IO, and A are the contents of the aforementioned registers D, R1c, IO, and A, respectively, and RIc
indicates the coil current value 1c at this point.

Next, the contents of register X (rightward movement af of rod 18)
i) is equal to or greater than the content Lp of the register LP (rightward drive stroke setting value of the rod 18; discharge period) (12), and if not, the timer dt
Start (18).

In this way, step 8-9-10-11-12-
8, when X≧LP (after the start instruction, the ejection period of the first beat ends), the current flowing through the electric coil 30 is reduced to zero (13), the relay 33 is switched, and the electric coil 3
Reverse the energization direction of 0 and set the reverse direction energization14),
At this point (first beat), the content P of register P is 1 (I5), so the content of register P is set to 2 (16),
This time, in order to apply the inhalation phase voltage of the first beat, the output data ■o is increased by a predetermined step every minute time elapses, and when the transient rush period t2 ends, the output data V
Let O be Vn (17). As a result, the voltage Vn during the inhalation phase
is applied to the electric coil 30 from the coil driver 35, and a reverse current flows through the electric coil 30 (the fluid space 50 in FIG. 2a is expanded and negative pressure is applied to the artificial heart 1).
.

After outputting the inhalation phase voltage Vn (17), the CPU 43 waits for the switching timing from the inhalation phase to the exhalation phase (
18). That is, when external synchronization is set, the system waits for the arrival of an external synchronization signal pulse (a signal that is generated one pulse per beat of the living heart and is assigned to the start point of the ejection period of the artificial heart). , when internal synchronization is set, an internal timer (program timer that takes a time limit of Tc) set by the pulsation setting flow (not shown) is used.
wait for timeout.

When the timing for switching from the inhalation period to the exhalation period comes, the current in the electric coil 30 is reduced to zero (19), the relay 33 is switched to positive direction energization (20), the register X is cleared (21), and the process proceeds to step 7.

With the above, the control of the exhalation/inhalation process for one beat from the start is completed. Immediately after the start, the position of the rod 18 is unknown, so if the initial position of the rod is on the right side, the bellows 19 will be excessively compressed during forward energization (discharge phase energization) and the rod 18
may stop moving to the right and continue to be energized in the forward direction, or conversely, if the initial position of the rod 18 is to the left, the discharge period will end before the bellows 19 is compressed excessively, and the compression may still continue. Even though it is possible to do so, the forward current supply may be stopped. Therefore, since it is expected that there will be variations in the load and moving speed of the electric coil 30 during the ejection period of the first beat immediately after the start, the detected current (
Calculation of the resistance value R of the electric coil 30 based on RIc) (
22) and the change to the correction coefficient based on the resistance value (23) are not executed. Note that at the time when control of one or more first beats is completed, the contents of register P are 2 due to execution of step 16.

The processing of the CPU 43 during the ejection period of the second beat is also the same as the processing of steps 7 to 14 described above, but when this is finished,
Since the content of the register P is 2, the CPU 43 proceeds from step 15 to 622 and calculates the resistance value R of the electric coil 30.
Calculate it. That is, R=Vo/RIc-R37 is calculated. Note that vo is the voltage applied to the electric coil 30, RIc is the content of the register RIc, the current value Ic of the electric coil 30 before the ejection period, and R37 is the register R
37, which is the resistance value of the current detection resistor 37. Next, the CPU 43 calculates the correction coefficient A=R/Rs and updates it in the register A.

Rs is the standard resistance value of the electric coil 3o. The correction coefficient A updated in this way is the stroke X of the next discharge period.
is used in the calculation (step 11).

After updating the correction coefficient A, the CPU 43 executes the processes (17 to 21) for the inhalation period of the second beat. This content is similar to the content of the process during the inhalation period of the first beat described above.

Thereafter, the processing for the third beat, fourth beat, fifth beat, etc. is executed in the same manner. Calculation of stroke X during the exhalation period of the third beat (11
), the correction coefficient A calculated (23) is used based on the resistance value R of the electric coil 30 calculated (22) after the processing of the exhalation period of the second beat ends and before proceeding to the processing of the inhalation period. Similarly, in calculating the stroke of the ejection period of the fourth beat, the correction coefficient A calculated immediately after the end of the ejection period of the third beat is used.
is used. The same applies below.

In this way, the current value Ic of the electric coil 30 is integrated (
11) When the stroke X of the rod 18 is calculated and it reaches the set value Lp, the discharge is switched to suction. , that is, the discharge flow rate of the artificial heart 1.

is adjusted. In this embodiment, this adjustment is performed by operating the keys on the operation board 44 to register Lp and/or Vp.
This is possible by changing the contents of . in this way,
The discharge flow rate can be adjusted without using a position detection means such as a potentiometer.

In addition, since the resistance value R of the electric coil 30 is detected and the correction coefficient A of the stroke calculation formula (integral formula) is updated accordingly, the variation in the resistance value R of the electric coil 30 (
Since the stroke calculation formula is corrected in response to changes in temperature (mainly caused by temperature changes), an accurate stroke, that is, a discharge flow rate, is maintained even if there is a change in resistance value due to a change in temperature of the electric coil 30.

In the above embodiment, the rising characteristics of the discharge pressure and suction pressure are fixed, but as described above, the moving speed dX/dt can be calculated by detecting the current value 1c of the electric coil 30. Therefore, it is also possible to control the rising and/or falling speeds of the discharge pressure and/or suction pressure.

That is, the current flowing through the electric coil 30 is controlled in a predetermined rising and falling pattern (this is done by the D/A converter 3).
Data V given to 6. This is achieved by outputting the data in a time-series manner in a predetermined rising and falling pattern.

Further, although the liquid pump 12 of the above embodiment uses the rod 18 and the bellows 19 as reciprocating members, the outer case 16 may be made into a cylinder and the bellows 19 may be replaced with a piston.

〔Effect of the invention〕

As described above, the pumping device of the present invention can significantly reduce the number of lateral elements per machine, and the space occupied by the device can be made extremely small. Not only potentiometers, etc.
The sensor for 1i feedback can be omitted, and the problem of sensor durability can also be improved.

[Brief explanation of the drawing]

FIG. 1 is a side view showing the appearance of an embodiment of the present invention. FIG. 2a is an enlarged longitudinal sectional view of the fluid pump 12 shown in FIG. FIG. 2b is a sectional view taken along line IIB-11B in FIG. 2a. FIG. 3 is an electric circuit diagram showing a 41+1g configuration of the motor driver 31 and pumping controller 42 shown in FIG. 1. FIG. 4 is a flowchart showing an overview of the control operation of the microprocessor 43 shown in FIG. 1.101: Artificial heart 2: Diaphragm 3
: Working chamber 4: Inner space 5.6: Check valve 7, 8: Cannulation! It, 901
:Tube 12.1201 :Liquid pump (liquid pump) 13:Ring 14:End member 15:Output port 16:Outer case 17
: Partition wall member ]8: Rod 19: Bellows (18, +9: Reciprocating member) 20A, 20 ports: Bearing 21, 22, 23.2/I: Support plate 2
5.26, 27, 28: Permanent magnet plate (magnetic field generation means)
29: Coil bobbin 29A: Arm 30: Electric coil (electric coil) 31: Motor driver 33: Relay 34 for switching current direction = Relay driver 35: Coil driver 36: D/A converter (33 to 36: Current supply means)
37: Resistor for current detection 38 Two low-pass filter 39: Amplifier 40: Hold circuit 41: A/D converter (37-41: Current detection means) 42.4201: Pumping controller 43:
Microprocessor (integration means 2 energization direction control means) 4
4: Operation board 50: Fluid space (fluid space) 51.52: End plate

Claims (1)

[Claims] A reciprocating member communicating with a fluid output port and contracting/expanding a fluid space containing an incompressible liquid, an electric coil for reciprocating the reciprocating member, and the electric coil. A liquid pump driven by a linear motor, comprising: magnetic field generating means for applying a magnetic field to the electric coil in a direction perpendicular to the direction in which it extends, and generating a moving force in the forward/backward direction corresponding to the forward/reverse energization direction in the electric coil; An energizing means for energizing the electric coil in the forward/reverse direction; a current detecting means for detecting the energizing current of the electric coil; an integrating means for integrating the energizing current detected by the current detecting means; and an integral value of the integrating means is set. A pumping device comprising: energization direction control means for instructing the energization means to reverse the energization direction when the value is reached.