JPH0380961A - Apparatus for preventing liquid dripping - Google Patents

Abstract

PURPOSE:To automatically hold suction quantity to a desired value by a method wherein the actual deformation quantity of a diaphragm is detected to be fed back to an operation apparatus and subjected to the comparative operation with a set value and a servo valve is controlled by an order apparatus so that the detected value approaches the set value. CONSTITUTION:A suction valve 6 is interposed between a pressure feed source 10 of a liquid to be discharged and a downwardly opened nozzle 7 so that the volume of a flow chamber 18 through which the liquid to be discharged flows is increased and decreased by the pressure of the pilot fluid supplied to the pressure chamber 34 demarcated from the chamber 18 by a diaphragm 26. The liquid to be discharged in the nozzle 7 after the pressure feed of the liquid to be discharged is stopped is sucked by the increase of the volume of the chamber 18 to prevent liquid dripping. At this time, the suction quantity of the liquid to be discharged is set by a data setting apparatus and the deformation quantities of diaphragms are detected by a detector 8. In an operation apparatus 2, the set signal of the apparatus 1 is compared with the detection signal of the detector 8 to perform operation and the pressure of the pilot fluid is controlled by a servo valve 5 and the operation result of the apparatus 2 is input to the valve 5 by an order apparatus 3.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention provides a method for discharging a liquid such as a reagent from a nozzle that opens downward, when the liquid to be ejected is stopped from discharging the liquid to be ejected from the nozzle. The present invention relates to a drip prevention device that prevents the liquid to be ejected from dripping after the ejection is stopped by suctioning the liquid inward.

Conventional techniques and problems to be solved by the invention Conventionally, as such a drip prevention device, the volume of a distribution chamber through which the liquid to be discharged flows is divided by the distribution chamber and a diaphragm in the distribution path in front of the nozzle. A suction valve is installed that increases or decreases depending on the pressure of the pilot fluid supplied to the pressure chamber.
There is a device that prevents dripping by sucking the liquid to be discharged in the nozzle after the pressure feeding of the liquid to be discharged is stopped due to an increase in the volume of the circulation chamber of the suction valve. Since it is an open control that controls the movement and cannot directly measure the amount of suction, it is necessary to adjust the suction valve itself by trial and error in order to set and adjust the amount of suction. The disadvantage is that it takes a long time to carry out.

Means for Solving the Problems The present invention provides a data setting device for setting the amount of suction of the liquid to be ejected, a detection device for detecting the amount of deformation of the diaphragm, and a data setting device for setting the suction amount of the liquid to be ejected. A calculation device that compares and calculates the setting signal of the setting device and the detection signal of the detection device, a servo valve that controls the pressure of the pilot fluid, and a command device that inputs the calculation results of the calculation device to the servo valve are provided. The configuration was as follows.

Functions and Effects of the Invention The present invention has the above configuration, detects the actual amount of deformation of the diaphragm, feeds it back to the calculation device, compares it with the set value, and then uses the command device to make the detected value approach the set value. Since the servo valve is controlled, the suction amount can be automatically maintained at a desired value, and remote control is also possible, which has the effect of significantly improving work efficiency.

EXAMPLE Hereinafter, an example of the present invention will be described based on the accompanying drawings.

In FIG. 1, 1 is a data setting device for setting the desired suction amount and suction time as digital values manually input using keys or analog values input using a dial, and the set values are input to the calculation device 2 for detection as described below. Device! The data on the suction amount and suction time of the suction valve 6 fed back from the suction valve 8 are compared and calculated. In addition, when the input to the data setting device at is an analog value by dial input, it is converted into a digital value and calculation is performed. The results of the comparison calculation performed by the arithmetic device 2 are input to the command device 3, and a digital value corresponding to the voltage supplied to the electro-pneumatic proportional valve 5 and its supply time, which will be described later, is output. This digital value is converted into an analog value by the digital-to-analog converter 4 and input to the electropneumatic proportional valve 5, and pilot air at a pressure corresponding to the input voltage is supplied to the suction valve 6 for a time corresponding to the voltage application time. After the supply of the liquid to be ejected from the supply source IO is stopped, suction of an amount corresponding to the pressure fluctuation of the pilot air is performed at the nozzle 7 for a time corresponding to the fluctuation time. The suction of the suction valve 6 is performed by the fluctuation of the diaphragm 16, which will be described later.The amount of deformation and the time required for deformation are detected as an analog value by the detection device 8, and this is converted into a digital value by the analog-to-digital converter 9. It is input to the arithmetic unit 2.

As shown in FIG. 2, the suction valve 6 of this embodiment has a flow channel chamber 18 between the inlet 14 and the outlet 15 of the main body 13, the upper surface of which is airtightly partitioned by a first diaphragm I6. The inlet 14 is connected to the supply source 10 of the liquid to be discharged, and the outlet! 5 are respectively connected to the nozzle 7,
A lifting rod 20 whose lower end surface is in contact with the diaphragm 16 is disposed in the accommodation chamber 9 formed above the first diaphragm I6, and two discs 2 are mounted in the upper small diameter portion 2I of the lifting rod 20.
3.24 is fitted across the second diaphragm 26,
By caulking the protrusion 22 of the small diameter portion 2I, the discs 23, 24 and the second diaphragm 26 are integrally fixed to the lifting rod 20, and the peripheral edge of the second diaphragm 26 is attached to the body 13. A pressure chamber 34 is formed between the second diaphragm 26 and the cover 25 by pressing the cover 25ζ, and a coil spring is installed between the lower step 27 of the accommodation chamber 19 and the lower disc 24. 28 is attached to urge the second diaphragm 26 upward, and the storage chamber 19 is communicated with the outside air through the ventilation hole 29. A pilot air port 30 connected to the air supply port of the electropneumatic proportional valve 5 is formed at an eccentric position on the cover 25, and a direct detection device 8 is formed around the through hole 31 formed at the center position. The dynamic potentiometer is airtightly attached to prevent the air in the pressure chamber 34 from leaking, and the detection pin 33 passes through the through hole 3I and comes into contact with the protrusion 22 of the small diameter portion 21 of the lifting rod 2o.

Next, to explain the operation of this embodiment, while the liquid to be discharged is being supplied, the pressure in the pressure chamber 34 supplied from the electropneumatic proportional valve 5 to the pilot air port 30 is high, and the second diaphragm 2
6 elastically compresses the coil spring 28 and is in the lower position shown by the chain line in FIG.
The diaphragm I6 is also in the lower position shown by the chain line, and the volume of the flow chamber 18 is small. The discharge pressure of the pilot air is reduced by a certain value for a certain period of time, and the pressure in the pressure chamber 34 decreases, causing the first diaphragm 16 to rise together with the second diaphragm 26 and the lifting rod 20 as shown by the solid line in the figure. - Distribution room! The volume of the nozzle 8 increases and the liquid to be ejected from the nozzle 7 is suctioned. The deformation of the diaphragm 16 corresponds to the vertical movement of the lifting rod 20.
This is detected as a movement of the detection pin 33 of the direct-acting potentiometer, which is the detection device 8, and as described above, the amount of variation and the variation time are fed back to the calculation device 2, and the settings are input to the data setting device 1. The value that is compared with the value and calculated so that the difference becomes zero is input to the command device 3,
The electropneumatic proportional valve 5 is controlled by the command device, and the lifting rod 2
The zero variation, ie the deformation of the first diaphragm 16, is automatically controlled to match the input value of the setting device I.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2 is a sectional view of a suction valve. l: Data setting device 2: Calculation bag w 3: Command device 5
: Electro-pneumatic proportional valve (servo valve) 6: Suction valve 7: Nozzle
8: Detection device lO: Supply source of liquid to be discharged 14: Inlet IS: Outlet 16: First diaphragm IS: Distribution chamber 20: Lifting rod 26: Second diaphragm 33
:Detection pin 34:Pressure chamber

Claims (1)

[Scope of Claims] The volume of a flow chamber through which the liquid to be discharged flows is supplied to a pressure chamber partitioned by the flow chamber and a diaphragm between a pressure source of the liquid to be discharged and a nozzle opening downward. A suction valve that increases or decreases depending on the pressure of the pilot fluid is interposed, and by increasing the volume of the circulation chamber of the suction valve, the liquid to be discharged in the nozzle is sucked after the pressure feeding of the liquid to be discharged is stopped, thereby preventing liquid dripping. A data setting device for setting a suction amount of the liquid to be discharged;
a detection device that detects the amount of deformation of the diaphragm, a calculation device that compares and calculates a setting signal of the data setting device and a detection signal of the detection device, and a servo valve that controls the pressure of the pilot fluid; A drip prevention device characterized in that the servo valve is provided with a command device for inputting the calculation results of the calculation device.