JPH01227882A - Slight flow rate pump - Google Patents

Abstract

PURPOSE:To offer a small and high precision pump by arithmetically operating the findings from time comparison of the detected value with the set value for pump flow rate, amplifying the findings from the arithmetical operation to control the driving of the pump, and integrating the flow rate sensor, a computing element and an amplifier. CONSTITUTION:A pump 21 driven by an actuator 29 using a bymorf diaphragm sucks fluid into a pump chamber and discharges it into the sensor chamber of a flow rate sensor 13. The detected value of the flow rate sensor 13 is sent to a computing element 17a to compute an error between the value and the set value in a flow rate setter 36. The voltage corresponding to the error is amplified by an amplifier 17b and then applied to an actuator 29. The pump 21 is driven to ensure the flow rate corresponding to the set value. Thus the flow rate of fluid may be controlled at high precise level by a pump of such simple and small constitution.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a microflow pump that can control fluid flow rate with high precision in liquid and gas supply devices for oil stoves, chemical equipment, medical equipment, etc. be.

[Conventional technology] Conventionally, the smallest fluid can be processed at a high flow rate of 11! In order to discharge at 1 degree, the components of the pump had to be highly precise and operated at 1 degree, which meant that the pump had a complex and large structure. In addition, the conventional method only commands the value of the discharge flow rate, which changes depending on the actual temperature, specific gravity, viscosity, etc. of the discharge body, so in order to obtain a highly accurate and stable flow rate, these conditions must be met. It had to be kept constant. In addition, in large-scale fluid supply equipment for general industrial use, such as in chemical plants, the discharge F & amount of the pump is measured with a flow meter, and this is converted into an electrical signal to control the pump, or the control valve is
1110, but these are used exclusively for large-scale and large-flow applications.

[Problem to be Solved by the Invention] An object of the present invention is to provide a microflow pump that is simple in construction and is composed of parts that do not require high precision, but that can control the flow rate with high precision.

Means for Solving Problem E] In order to achieve the above object, the configuration of the present invention includes a pump that suctions and discharges fluid, a flow sensor that electrically detects the discharge flow rate from the pump, and a flow rate sensor that electrically detects the discharge flow rate from the pump. It consists of a driver that compares and calculates an output signal and a signal of a flow rate setting value, and an amplifier that amplifies the output of the driver nB and uses it as a driving power source for the pump.

[Function] The flow m of the fluid discharged from the pump 21 is detected by the flow sensor 13.
The deviation from the set value set by the flow rate setting device 36 is calculated, and the actuator 2
9) Supply the corrected drive power. In other words, pump 2
The pump 21 feeds back the discharge flow rate of 7 to the pump 29 to improve the accuracy of the discharge flow, and it is not necessary for the pump 21 alone to discharge the flow rate corresponding to the set value, so it is not necessary to use high-precision parts or high-precision operation. is not required.

Since a bimorph imaging plate is used as the actuator 29, the configuration is simple and small, no mechanical coupling mechanism is required, the operation is stable, and a stable flow rate can be obtained.

[Embodiments of the invention] FIG. 5 shows a schematic configuration of a microflow pump according to the present invention.

A diaphragm type pump 21 driven by an actuator 29 sucks fluid into the pump chamber when the pump chamber is expanded, and discharges it into the sensor chamber of the flow rate sensor 13 when the pump chamber is contracted. Since the outflow port of the sensor chamber is equipped with a restriction,
A pressure change in the sensor chamber is detected by a flow rate sensor 13 consisting of a differential transformer or the like, and this detection signal is applied to a computing unit 17a. Detected value and 81m setting device 36 with sieve device 17a
The deviation from the flow rate setting value is determined and added to the amplifier 17b. The voltage corresponding to the deviation is amplified by the amplifier 17b and applied as alternating current to the actuator 29, causing a current m
The actuator 29 of the pump 21 is controlled in order to obtain a flow rate corresponding to the set value.

Figure 1.2 shows the specific configuration of the microflow pump.

The pump 21 has a main body 33 overlaid with a clamping plate 32 sandwiching an elastic plate made of rubber or the like, which is made by cutting out the check valves 25 and 2.
The peripheral edge of the diaphragm 24 is pressed onto this by a presser plate 19, and a cup-shaped cover 31 is further placed on top of the diaphragm 24, which is then connected with a plurality of bolts 22. cover 31
In the atmospheric chamber 40 covered by the diaphragm 24, the actuator 29 is stacked and bonded to the diaphragm 24, and its center portion is sandwiched between the protrusion 28 of the holding plate 32 and the cushion 27 provided on the protrusion 26 of the cover 31.

The actuator 29 has electrode plates 29 made of piezoelectric ceramic on both upper and lower surfaces of a circular electrode plate 29a made of conductive metal.
conductors 23 and 30 connected to these electrode plates are connected to the amplifier 17. A pump chamber 39 defined between the diaphragm 24 and the clamping plate 32 is communicated with the inlet 18 via the check valve 25 and the passage 35 . Further, the pump chamber 39 communicates with the sensor chamber 4 of the VTM sensor 13 via the check valve 2 and the passage 20.

The flow layer sensor 13 has a diaphragm 3 sandwiched between a housing 7.9 consisting of two parts, and a sensor chamber 4 and an atmospheric chamber 1.
2 is divided into sections. The sensor chamber 4 is communicated with an outlet 8 through a diaphragm 6. A presser plate 5 is superimposed on the diaphragm 3, and a spring 16 is interposed between the housing 9 and the presser plate 5. A movable core 14 is supported by the holding plate 5, and a differential transformer 15 surrounding the movable core 14 is supported by a cover 38 on the wall of the housing 9. Housing 7.9 and cover 38
are connected by a plurality of bolts 10, and further connected to the main body 33 with an O-ring 34 interposed in the passage 20.

The operational amplifier 17 coupled to the main body 33 is a sieve 17a.
It has a generally known circuit configuration including an amplifier 17b and an FItl setting device (knob) 36 to set the discharge flow rate.

Although the flow rate sensor 13 is of a differential pressure detection type, other flow rate sensors may be used.

Next, the operation of the microflow pump according to the present invention will be explained. As shown in FIG. 4, when AC power is applied between the central electrode plate 29a of the bimorph diaphragm that constitutes the actuator 29 and the electrode plates 29b on both sides, a flat disk-like shape is normally observed. Things become curved and deformed. That is, since the center of the bimorph diaphragm is restrained by the protrusions 26 and 28, the peripheral edge deforms vertically into a bowl shape. When the bimorph imaging plate deforms upward into a bowl shape, the pump chamber 39 expands, and fluid is sucked into the pump chamber 39 from the inlet 18 through the passage 35 and the check valve 25.

On the other hand, when the bimorph diaphragm deforms downward into a bowl shape, the pump chamber 39 contracts, so fluid pushes open the check valve 2 and flows into the sensor chamber 4 through the passage 20. The fluid sequentially discharged into the sensor chamber 4 by such a pumping action exerts a pressure on the diaphragm 3 that is approximately proportional to the discharge flow rate due to a fluid resistance of 6. This pressure causes a displacement of the movable core 14 against the force of the spring 16, causing the movable core 1
The displacement of 4 is detected as a voltage change of the differential transformer 15. This voltage is applied to the flow rate setting device 36 in the W4 bullet amplifier 17.
The voltage corresponding to the polarization is amplified and applied to the actuator 29 as an alternating current voltage. In this way, the amplitude of the actuator 29 is controlled to obtain the discharge flow rate set by the flow rate setting device 36.

Instead of varying the amplitude of the actuator 29 by changing the voltage ilJ'wJ, the voltage may be kept constant and the frequency of the actuator 29 may be varied by controlling the power supply frequency.

Furthermore, if the measurement time of the discharge flow l measured by the flow rate sensor 13 is instantaneous, a so-called hunting phenomenon may occur in the discharge flow l of the pump 21. It is preferable to calculate this and then operate the actuator 29 based on this.

In the embodiment shown in FIG. 3, a pillar 24a is integrally formed at the center of the diaphragm 24, which is bonded to the bimorph rjA#J plate constituting the actuator 29 by bonding with an adhesive or the like. At the same time, the cushion 27 that presses the upper side of the actuator 29 is also fitted and supported in a hole provided in the protrusion 26 of the h-bar 31. This suppresses misalignment of the actuator 29.

[Effects of the Invention] As described above, the present invention includes a pump that suctions and discharges fluid, a sensor that electrically detects the discharge flow rate from the pump, and an output signal from the flow rate sensor and a signal of the flow rate setting value. Since we have integrated a compensator that performs comparison calculations between the
Changes in fluid pressure due to changes in the pump's discharge flow rate are converted to mechanical displacement of the diaphragm, and this mechanical displacement is electrically detected and input to the operational amplifier, so it corresponds to the deviation from the set flow rate. voltage is applied to the actuator of the pump, thus ensuring reliable operation and maintaining the pump delivery flow rate at the set value with precision.

Since a bimorph diaphragm is used as the pump actuator, the configuration is simple, and by combining the flow rate sensor and operational amplifier, the overall size is small.
Get a precision pump.

[Brief explanation of the drawing]

FIG. 1 is a front sectional view of the Efl pump according to the present invention, FIG. 2 is a side view of the same, FIG. 3 is a side sectional view showing another embodiment of the main part of the actuator, and FIG. 4 is the operation of the actuator. FIG. 5, a front view showing the principle, is a schematic configuration diagram of a microflow pump. 3.24: Diaphragm 4: Sensor chamber 6: Aperture 1
3: R1 sensor 14: Movable iron core 17: Fraud amplifier
29: Actuator 36: Flow rate setting device 39: Pump chamber

Claims (1)

[Claims] A pump that suctions and discharges fluid, a flow sensor that electrically detects the flow rate discharged from the pump, and a calculator that compares and calculates an output signal from the flow sensor and a signal of a flow rate setting value,
A microflow pump characterized by comprising an amplifier that amplifies the output of a computing unit and uses it as a driving power source for the pump, and is configured in an integrated manner.