JPH0777285A - Retraction valve - Google Patents

Abstract

PURPOSE:To provide a retraction valve which is directly controlled on the basis of an electric signal. CONSTITUTION:When a pulse signal is inputted to a stepping motor 5, an output shaft 16 is precisely rotated in the normal/reverse direction according to the signal. As the output shaft 16 is screwed up with a nut 24 fixed in the stepping motor 5, the output shaft 16 advances/retracts according to the rotation. In this way, a diaphragm 7 is actuated via an actuator 8, and the volume of a flow chamber 6 is varied. Therefore, the diaphragm 7 is advanced so as to reduce the volume of the flow chamber 6 during the flow of liquid, while the diaphragm 7 is retracted according to a stop of discharge from a nozzle B so as to increase the volume of the flow chamber 6, and consequently, the retraction occurs in the tip of the nozzle B. In this way, advance/retraction of the diaphragm 7 is carried out by directly driving the stepping motor 5 on the basis of the electric signal, so that precise control with high responsiveness is carried out.

Description

Detailed Description of the Invention

[0001]

[Industrial application] When a liquid that is susceptible to deterioration when exposed to air is accurately discharged from a nozzle that opens downward by a fixed amount, if the liquid is left as it is after it has stopped discharging, it will collect at the tip of the nozzle. Since the liquid touches the air and deteriorates, it is necessary to suck back a certain amount into the nozzle.If the sucking back speed is not appropriate, the liquid may drop along the inner wall of the nozzle and accumulate at the tip of the nozzle. There is.

According to the present invention, when the liquid to be ejected is ejected from a nozzle having a downward opening, when the ejection of the liquid to be ejected is stopped, the liquid to be ejected is sucked into the nozzle by a desired amount at a desired speed. Regarding the suck back valve.

[0003]

2. Description of the Related Art In such a suck-back valve, the volume of the circulation chamber is expanded by the retraction of a diaphragm defining one surface of the circulation chamber in which the liquid flows, so as to suck back the liquid. In this case, the electric signal was input to the electropneumatic proportional valve to be converted into air pressure, and the diaphragm was operated by that air pressure, so the responsiveness was low due to the compressibility of air, and the control accuracy was insufficient. There was a drawback.

[0004]

SUMMARY OF THE INVENTION The problem to be solved by the present invention is to provide a suck-back valve which is directly controlled by an electric signal.

[0005]

Means for Solving the Problems As a means for solving the above problems, the present invention provides a diaphragm that defines one side of a flow chamber in which a liquid flows, and a diaphragm that is attached in a direction in which the volume of the flow chamber increases. A stepping motor having a biasing actuating body and an output shaft that pushes the actuating body in a direction against the biasing force is slidable in the axial direction, and is formed on the output shaft by being fixed to the stepping motor. It is configured to include a nut that is screwed into the male screw.

[0006]

The present invention has the above-mentioned structure, and when a pulse signal is input to the stepping motor, the output shaft rotates accurately in the forward and reverse directions according to the signal. Since the output shaft is screwed into a nut fixed to the stepping motor, it moves forward and backward as it rotates. This allows
The diaphragm operates via the actuating body, and the volume of the flow chamber changes.

Therefore, during the flow of the liquid, the diaphragm is advanced to reduce the volume of the flow chamber, and when the discharge from the nozzle is stopped, the diaphragm is retracted to increase the volume of the flow chamber. Causes suction back at the nozzle tip. Here, since the diaphragm is moved forward and backward by directly driving the stepping motor by an electric signal, there is an effect that the response is high and precise control is performed.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below with reference to the drawings.

In the figure, A is an on-off valve for the liquid to be ejected, and B is
Is a nozzle for ejecting the liquid to be ejected downward, and C is a suction valve according to the present invention interposed therebetween.

The suction return valve C is a stepping body mounted through a lower body 1 having a flow passage 2 connecting the opening / closing valve A for the liquid to be discharged and the nozzle B, an upper body 3 fitted to the lower body 1 and a support 4. It consists of a motor 5.

The lower body 1 has a flow chamber 6 connected to the flow passage 2.
Is formed, the upper surface of which is covered by the diaphragm 7, and the peripheral edge of the diaphragm 7 is the lower body 1.
It is sandwiched between the upper body 3 and the upper body 3, and the central portion is the actuation body 8
Is screwed to the lower surface of the.

A small-diameter portion 10 of the actuating body 8 is tightly and slidably fitted in a central hole 9 formed in the upper main body 3, and a pin is formed in a lateral hole 11 formed in the upper portion of the small-diameter portion 10. 12 is inserted, one end of which protrudes from the lateral hole 11 and is fitted into the groove 13 formed in the upper body 3 to disable the rotation of the operating body 8. The operating body 8 expands the elastic force of the coil spring 14. Is pushed up by and is in contact with the output shaft 16 of the stepping motor 5. The upper main body 3 is formed with a vent hole 15 for allowing the actuator 8 to move up and down freely.

In the stepping motor 5, a coil 18 is arranged on a substrate 17, and a rotor 19 having a synthetic resin core body 20 filled in the center of a permanent magnet 21 is rotatably arranged therein. The center hole 22 of the core body 20 has a truncated circular shape only at the upper end thereof, and the output shaft 16 fitted to this also has a truncated circular upper half, and the nut 24 is fixed to the center of the board 17, A male screw 23 formed on the lower portion of the output shaft 16 is screwed into a nut 24, and the rotor 1
When the output shaft 16 rotates by the rotation of 9, the output shaft 16 moves upward or downward according to the rotation direction by being screwed with the nut 24. Reference numeral D denotes a suck-back control device which controls how much and how fast the valve is sucked back after the on-off valve A is closed.

E is a pulse transmission device, which is adapted to input a pulse signal to the pulse motor 5 in response to a command from the suck-back control device D.

Next, the operation of this embodiment will be described.

While the on-off valve A is opened and the liquid to be ejected is ejected from the nozzle B, a positive pulse signal is issued from the pulse transmission device E in response to a command from the suck-back control device D and the rotor of the pulse motor 5 is rotated. 19, the output shaft 16 is moved downward by screwing with the nut 24, and the operating body 8 is pushed down, the diaphragm 7 is pushed down, and the volume of the flow chamber 6 is reduced.

Here, when the on-off valve A is closed, the suck-back control device D is actuated and a negative pulse signal is issued from the pulse transmission device E, so that the rotor 19 of the pulse motor 5 is rotated.
Is reversed. Then, the output shaft 16 is moved upward by screwing with the nut 24, the actuating body 8 is pushed up by the elastic force of the coil spring 14, and the diaphragm 7 screwed to this is pulled up, whereby the volume of the flow chamber 6 increases. Then, the liquid to be ejected in the nozzle B is sucked back.

In the present embodiment, the sucked back liquid is sucked back by driving the diaphragm 7 by the pulse motor 5, so that the sucked back amount can be arbitrarily set and the sucking start can be controlled at the beginning. The suck-back speed can be arbitrarily controlled so that the suck-back is performed rapidly, and then slowly, so that the suck-back can be performed under optimum conditions.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment of the present invention.

[Explanation of symbols]

 2: Flow path 5: Stepping motor 6: Flow chamber 7: Diaphragm 8: Actuator 14: Coil spring 16: Output shaft 19: Rotor 23: Male screw 24: Nut A: Open / close valve B: Nozzle

Claims (1)

[Claims] 1. A diaphragm that defines one surface of a flow chamber in which liquid flows, an actuating member that biases the diaphragm in a direction in which the volume of the flow chamber increases, and a resisting force of the actuating member. A stepping motor having an output shaft that is pressed in the axial direction slidable in the axial direction, and a nut that is fixed to the stepping motor and that is screwed into a male screw formed on the output shaft. Suck back valve.