JPH08173885A - Fluid supplying device - Google Patents

Abstract

PURPOSE: To provide a liq. supplying device capable of very small amount, high speed and high accurate intermittent discharging, capable of transporting a high viscosity fluid and powder and also eliminating dripping, dropping, etc. CONSTITUTION: The device is provided with a fluid transporting part formed between an intake hole and a discharge nozzle 27 of a liq. and a rotor 25 and a fixed member 19 housing this rotor 25 and a shaft 10 connected with the rotor. Therefore, ultra-high speed intermittent discharge, achievement of ultra- high accuracy and achievement of ultra-fine flow rate for a feed rate are contrived by constituting the device of an actuator 31 for giving a relative revolving motion and a rocking motion between this shaft 10 and the fixed member and a compressed gas supply part provided in the vicinity of a controlling part being its driving source and a discharge nozzle and supplementing a discharge function of the liq. linked with a discharge from the discharge nozzle of the liq.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention quantitatively discharges and supplies various liquids such as adhesives, cream solders, greases, paints, hot melts, chemicals and foods in the production process in the fields of electronic parts, home appliances and the like. The present invention relates to a fluid supply device.

[0002]

2. Description of the Related Art Liquid ejecting apparatuses (dispensers) have been used in various fields, but with the recent needs for miniaturization and high recording density of electronic parts, the supply amount of fluid materials can be controlled with high accuracy. In addition, stable control technology is required.

Taking the field of surface mounting (SMT) as an example, for example, speeding up of mounting, miniaturization, high density, high quality,
In the trend of unmanned operation, the problems of dispensers can be summarized as high-accuracy coating amount, shortening of discharge time, and miniaturization of coating amount per time. As a conventional liquid ejecting apparatus, an air pulse type dispenser as shown in FIG. 10 has been widely used from the past. For example, “Automation Technology '93 .25 Vol. 7”
The technology is introduced in. The dispenser according to this method uses a fixed amount of air supplied from a constant pressure source in the container 1
It is applied in a pulsed manner in 50 (cylinder), and cylinder 1
A certain amount of fluid corresponding to the increase in the pressure in 50 is discharged from the nozzle 151.

As an alternative to the above-mentioned air pulse system, a dispenser using a rotary positive displacement uniaxial eccentric pump, which is commonly called a Mono pump, has been put into practical use. Since the mono pump has a snake-like movement, it is also called a snake pump, and the details of the technique are introduced in, for example, "Piping Technology, '85 .7 July". FIG. 9 shows an example of the structure.

100 is a main shaft (drive shaft), 1
01 is a ball bearing, 102 is a snake pump rotor, 10
3 is a stator. The rotor 102 and the coupling rod 106, and the coupling rod 106 and the drive shaft 100 are connected by a universal joint. The rotor 102 is a so-called male screw having a perfect circular cross section, and the stator 103 as a female screw corresponding to this male screw has a hole having an oval cross section.

When the rotor 102 is fitted into the stator 103 and the rotor 102 is rotated about the eccentric shaft center, the rotor 102 swings while rotating inside the stator 103. As a result, the rotor 102 and the stator 10
The fluid contained between the three is continuously sent out from the suction side to the discharge side by the infinite piston movement without breaks.

[0007]

However, these types of dispensers have the following problems.

[1] Problems of dispenser of air pulse system (1) Dispersion of discharge amount due to pulsation of discharge pressure (2) Dispersion of discharge amount due to head difference (3) Change of discharge amount due to change of liquid viscosity In the above (1) The phenomenon is more remarkable as the tact time is shorter and the ejection time is shorter. Therefore, various measures have been taken, such as providing a stabilizing circuit for equalizing the height of the air pulse.

In the above (2), since the volume of the cavity 152 in the cylinder varies depending on the remaining amount H of the liquid, when a constant amount of high pressure air is supplied, the degree of pressure change in the cavity 152 depends on the H. The reason is that it will change significantly. If the remaining amount of liquid decreases, the coating amount will decrease by, for example, 50 to 60% compared to the maximum value. Therefore, measures such as detecting the liquid remaining amount H for each ejection and adjusting the time width of the pulse so that the ejection amount becomes uniform are taken.

The above item (3) occurs, for example, when the viscosity of a material containing a large amount of solvent changes with time. As a measure for this, a measure has been taken in which the tendency of the viscosity change with respect to the time axis is programmed in the computer in advance and, for example, the pulse width is adjusted so as to correct the influence of the viscosity change. None of the measures against the above problems has become a drastic solution because the control system including the computer becomes complicated and it is difficult to cope with irregular environmental conditions (temperature, etc.).

[2] Problems of Dispenser by Snake Pump In the case of this snake pump, since it is a positive displacement type in which a fluid is contained in a closed space of a constant volume and is transported, a viscosity change and a pump It has a constant flow rate characteristic that is unlikely to be affected by changes in the load on the discharge side. Therefore, we will try to apply this snake pump as a dispenser for high-speed intermittent application instead of the conventional air pulse method. However, even if the main shaft of the snake pump is driven to rotate intermittently, it is difficult to intermittently discharge the transport fluid. The reason is that the fluid inside the pump enclosed between the rotor 102 and the stator 103 and the fluid outside the pump discharged from the nozzle are continuous continuums, and there is no mechanism for interrupting this continuous continuum. Is.

[0012]

In order to solve the above problems, in a liquid supply apparatus according to the present invention, a liquid suction hole and a discharge nozzle are formed between a rotor and a fixing member for housing the rotor. A liquid transporting section, a shaft connected to the rotor, a means for imparting a relative rotational movement and a swinging movement between the shaft and the fixed member, a control section which is a drive source thereof, and the discharge A compressed gas discharge part provided in the vicinity of the nozzle to assist discharge of the liquid in cooperation with discharge of the liquid from the discharge nozzle, and a supply source for supplying the compressed gas to the discharge part. It is a feature.

[0013]

The high-pressure gas is supplied to the tip of the discharge nozzle of the positive displacement type micro pump (liquid supply unit) having the function of reliably transporting a certain amount of liquid so as to flow along the streamline direction.
At this time, the micro pump is simultaneously driven to allow a minute amount of liquid to flow out from the discharge nozzle. If no high-pressure gas is supplied, the liquid discharged from the nozzle adheres to the outer wall of the nozzle in a spherical shape due to the effect of surface tension, and does not easily separate from the nozzle until the weight of the liquid overcomes the surface tension. The high-pressure gas imparts momentum to the liquid flowing out of the nozzle and cuts off the effect of surface tension, so that the liquid can be smoothly separated from the nozzle and can fly to a distance.

A high-speed intermittent coating dispenser can be realized by intermittently driving the micro pump and supplying high pressure air to the tip of the discharge nozzle.

Further, it is more effective if the high-pressure air of the pulse train is applied in a state synchronized with the intermittent driving of the micropump.

If a uniaxial eccentric snake pump is used for the micropump which is the liquid supply device of the present invention, and the rotor and the stator of the snake pump are housed near the inner wall of the discharge nozzle, the performance as a dispenser is improved. It will be dramatically improved. The reason is that, in addition to the inherent characteristics of the snake pump, that is, it does not depend on the temperature change (viscosity change) that allows powder transport suitable for transporting highly viscous fluids, the following effects can be obtained.

The above-described effect capable of preventing dripping and dropping of the nose is that the snake pump also functions as a valve for blocking the upstream side and the downstream side of the liquid flow path. Further, if the snake pump is stopped and then reversed a little, the pump chamber becomes a little under negative pressure, so that the fluid is sucked again from the tip of the nozzle and the dripping can be completely avoided. Furthermore, paying attention to the fact that the movement of the snake pump rotor is a combined regular movement of rotation and oscillation,
For example, the rotors can be driven in a non-contact manner with respect to the stator by synchronously operating them by independent actuators. If the present invention is applied to such a non-contact drive snake pump, in addition to the above effects, highly accurate intermittent discharge can be achieved for the following reasons. Due to the non-contact drive, the clearance between the rotor and the stator has a constant change characteristic at any place, and the influence of the internal leak on the discharge flow rate is also constant. As a result, even if the clearance between the rotor and the stator is a little large, it is possible to obtain the discharge amount without variation as predicted in advance.

[0018]

EXAMPLE An example in which the present invention is applied to a dispenser for supplying a liquid at a minute flow rate will be described below.

In FIG. 1, 10 is a main shaft, 11 is a rotary actuator, and a motor rotor 12 is a motor stator, 13 to 19 are fixing members, and 20 and 21 are fixing members 1.
3, 14, 15, 16, 17, 18, 19 and upper thrust fluid bearings and lower thrust fluid bearings formed between the spindle 10, 22 is a flange-shaped seal portion, 23 is a suction hole, and 24 is the spindle 10. The screw groove pump formed in step 1, 25 is a snake pump rotor, 26 is a snake pump stator, and 27 is an upstream discharge nozzle. In the figure, only the rotor 25 and the stator 26 of the snake pump are exaggerated in their amplitude shapes. 28 is a rotor of a magnetic bearing which is a swing actuator, 29 is a stator of the magnetic bearing, 30a and 30b are X-axis displacement sensors for detecting the radial position of the main shaft 10, 30c (not shown),
30d (chain line) is a Y-axis displacement sensor.

The X-axis displacement sensors 30a and 30b and the Y-axis displacement sensors 30c and 30d are provided so as to be orthogonal to each other.
The Y-axis sensor 30d arranged on the back side of the drawing is shown by a chain line. The rotor 28, the stator 29, the X-axis displacement sensors 30a and 30b, and the Y-axis displacement sensors 30c and 30d determine the radial position of the axis O ₁ of the main shaft 10 and generate a regular swinging motion on the axis O _1. The magnetic bearing actuator 31 is configured. Further, 32 is a rotor of an encoder for detecting the rotation angle and rotation speed of the main shaft 10, and 33 is a stator, which is provided between the main shaft 10 and the fixing member 13. A rotary actuator 35 that regularly rotates the main shaft 10 is configured based on the rotational position information obtained by the encoder.

36 is a spacer, 37 is a downstream nozzle, 3
8 is an air flow passage formed between the stator 26 and the spacer 36, 39 is an air supply hole, and 40 is a screw portion for fastening the spacer 36 to the fixing member 19. FIG. 2 shows an enlarged view of the tips of the nozzles 27 and 37.

The high-pressure air is discharged from the downstream nozzle 37 together with the liquid flowing in from the supply hole 39, flowing out of the upstream discharge nozzle 27 through the flow passage 38.

The snake pump, which is the object of the present invention, causes the drive-side main shaft connected to the rotor to move eccentrically (oscillate) in order to reciprocate the rotor linearly within the stator having an oval cross section. However, it is a publicly known one that is rotated at the center of the eccentric shaft. FIG. 3 shows the operating principle of the snake pump, where 1 is the basic circle and 2 is the inscribed circle. O ₁ is the center of the inscribed circle 2, O ₂ is the center of the eccentric movement of the rotor, and 3 is the main axis centered on O ₁ . When the inscribed circle 2 rotates while rolling inside the basic circle 1 at the rotation speed ω, the inscribed circle center O ₁ swings around the center O ₂ at the rotation speed ω. Therefore, the main shaft 3 of the snake pump oscillates around the center O ₂ with the eccentricity ε while rotating at the rotation speed ω.

Also, the rotor of the pump portion for transporting the fluid
(Not shown in FIG. 3; 25 in FIG. 2) is a circle of the inscribed circle 2
It is a perfect circle formed around the circumference. This rotor is inside
Is a stator having an oval cross section (not shown in FIG. 1.
It is stored in 6) and the origin O ₂A linear motion passing through
I do.

In the fluid supply device to which the present invention is applied, the swing motion and the rotary motion are simultaneously applied to the main shaft 3 by two independent actuators. In the rotary actuator unit, the AC servomotor, the pulse motor, or the like makes a rotational motion of the rotational speed ω. On the other hand, the oscillating actuator section makes a regular oscillating motion by a combination of micro-actuator sine wave drive having a phase shift of 90 ° on the X axis and the Y axis, for example. This swinging motion is a turning motion that rotates around the origin O ₂ at the rotation speed ω.

The two movements, the rotation and the swing, are synchronously controlled so that the mutual phase difference is kept constant. For example, the phases of the swing motion and the rotary motion are determined based on one reference signal. By this synchronous control, the main shaft 3 makes a composite motion peculiar to the mono pump. As a result, the closed space formed between the rotor and the stator moves sequentially from the suction side to the discharge side, and a continuous pumping action is obtained. FIG.
A block diagram of the swing motion control unit 81 for driving the magnetic bearing actuator 31 is shown in FIG. This swing motion control unit 8
In No. 1, each shaft of the magnetic bearing is driven in synchronization with the rotational movement. The structural model of the magnetic bearing is shown in the figure, and the stator 29 is the X-axis stators 29a and 29b.
And Y-axis stators 29c and 29d. In order to give a swinging motion to the main shaft 10, a sine wave having a phase difference of 90 ° is given to the drive circuits of the X-axis stator and the Y-axis stator.

FIG. 5 is a block diagram of the entire control circuit of this embodiment. The rotation signal generator 82 outputs a frequency (pulse train) that determines the rotation speed and rotation position. One of the outputs is input to the rotary motion control unit 83. The rotary motion control unit 83 produces a signal for controlling the drive of the rotary actuator 35. On the other hand, in the swing motion control section 81, the pulse train obtained from the rotation signal generator 82 is sent to the X-axis and Y-axis signal processing section (FIG. 4) of the magnetic bearing actuator 31.
In FIG. 4, if the output from the encoder is fed back to the swing motion controller as shown by the chain line, the phase between the rotary motion and the swing motion can be controlled more accurately. In FIG. 2, the thrust fluid bearings 20 and 21 are known hydrodynamic bearings in which a shallow groove 32, commonly called a herringbone (fish bone), is formed on the surface of the collar. Fluid bearing 2
Lubricating oils 33 and 34 are enclosed between 0 and 21 and the fixing member. Due to the pumping effect of the shallow groove 32, the lubricating oils 33 and 34 do not flow out.

The main shaft 10 has two thrust fluid bearings 2 as described above.
Since it is supported by 0 and 21, it does not incline and its axial position is restricted. Therefore, due to the driving force of the magnetic bearing actuator 31, the main shaft 10 can perform the swinging motion while maintaining the vertical state.

The collar-shaped seal portion 22 is provided in order to prevent the transport fluid from entering the fluid bearing portion and the magnetic bearing portion, and the clearance between the collar and the axially opposed surfaces thereof is sufficient. It is set small. The thread groove pump 24 is formed in order to facilitate the inflow of the transport fluid into the snake pump portion in the embodiment.

The conventional snake pump using the universal joint has the following problems regarding the flow rate accuracy. In the case of the conventional method shown in FIG. 9, the rotor 102 basically has a cantilever support structure, and the stator 103 also functions as a bearing for supporting the rotor 102. Therefore, for example, the number of rotations of the spindle 100 is increased,
When the pressure on the discharge side increases due to the increase in the load on the pump,
The movement of the rotor 102, which does not have a sufficient positioning and holding function, tends to be unstable. As a result, the clearance between the rotor 102 and the stator 103 fluctuates, and the amount of internal leak fluctuates, resulting in poor flow rate accuracy. In addition, the secular change of the flow rate characteristic due to the uneven wear of the stator 103 and the rotor 102 is also a big problem. Therefore, since the Suinex pump is used as a dispenser, when the diameter of the rotor is reduced, the accuracy of the total discharge flow rate is limited to ± 10 to 20% due to the reason described above. Also, the flow rate of the dispenser has been made extremely small (for example, Q = 10 ^-5 cm ³ /
In order to meet the requirement of (sec or less), for example, the rotor diameter: D
When attempting to reduce the diameter to 0.5 mmφ or less, the conventional structure involving metal contact between the rotor and stator causes elastic deformation, oscillating wear, damage, etc. due to rotor strength deterioration, making it extremely difficult to put into practical use. Met. In the embodiment of FIG. 1 to which the present invention is applied, the movement of the rotor 25 and its absolute position are completely restricted by the magnetic bearing actuator 31. Therefore, the rotor 25 having a complicated snake shape can be kept in non-contact with the stator 26 during operation. The clearance between the rotor 25 and the stator 26 in one cycle of motion has a constant change characteristic at any place because the motion trajectory of the main shaft 10 is constant. Therefore,
The effect of the internal leak on the discharge flow rate is also constant, and even if the clearance between the rotor 25 and the stator 26 is slightly large, the discharge flow rate without variation can be obtained as predicted in advance.

In the pump of the present invention, the conventional universal joint (1 in FIG. 8) is provided between the rotor 25 and the main shaft 10.
04, 105) does not impede the flow of the transport fluid. Therefore, the snake pump for achieving a small flow rate is downsized, and even if the opening portion of the inlet is small, the transport fluid can smoothly flow into the snake pump.

As an application example of the present invention, the case where two independent actuators are used to obtain a combined motion of swing and rotation has been described above. A case will be described below where the present invention is applied to a fluid supply device that constitutes a non-contact type snake pump with one actuator (motor). Studies on levitation rotary motors that simultaneously have the two functions of a magnetic bearing and a motor have been made. For example, Oishi et al., Proceedings of the Japan Society of Mechanical Engineers (Vol. 58, No. 556, 199).
2 years). FIG. 8 shows an example of the above report. Two
00 is a rotor composed of four-pole permanent magnets, 201 is a stator composed of 12 poles, and 202 and 203 are displacement sensors. In this way, it is theoretically proved that rotation control and levitation control do not interfere with each other by combining a permanent magnet rotor and a multi-pole stator and applying rotating magnetic fields with different phase differences for rotation control and levitation control. Has been done. (Details omitted) The rotary levitation motor is known in this way, but it requires a displacement sensor and a control circuit for detecting the position of the rotor 200, like the conventional magnetic bearing.

FIG. 6 shows a second application example of the present invention.
Reference numeral 0 is a main shaft, 201 is a rotor of a motor that also serves as a rotary actuator and a swing actuator, 202 is a stator, 203
˜210 is a fixing member, 211 is a case for accommodating the fixing member, 212 is a suction hole, 213 is a thread groove pump formed on the main shaft 200, 214 is a snake pump rotor,
Reference numeral 15 is a snake pump stator, 216 is an upstream discharge nozzle, 217 is an upper thrust bearing, 218 is a lower thrust bearing, 219 is a seal portion, 220 is a radial displacement regulation rotor mounted on the main shaft 200, and 221 is 208 and 2
Lubricating oil enclosed in 20 gaps. The fixing member 208 also functions as a radial displacement regulation stator.

221 is a spacer, 222 is a downstream nozzle, 223 is the stator 215 and the spacer 221.
An air flow passage 224, an air supply hole 224, and a screw portion 225 for fastening the spacer 221 to the fixing member 210. Here, attention is paid to the following.

In the case of the minute flow rate dispenser, the eccentricity ε of the swinging motion is extremely small, and ε = 0.1 to 0.5 mm.
The degree is enough.

The movement of the main axis draws a constant locus (hypocycloid curve). In the present embodiment utilizing the above, the radial position of the main shaft 200 is, as shown in FIG.
Restrained by 08. Therefore, it is not necessary to control the axial position of the spindle 10 even if the spindle 200 is subjected to a combined motion of rotation and swing using the principle of the rotary levitation motor.
It suffices to press the radial displacement regulation rotor 220 against the inner surface of the radial displacement regulation stator 208 as shown in FIG. Therefore, the control system can be simplified and the radial displacement sensor can be omitted. Of course, as the magnetic levitation motor used in the present invention, a step motor, a reluctance motor, an induction motor or the like can be applied.

FIG. 7 shows, as a third embodiment of the present invention, an example in which the electrostatic attraction action is added to the present invention to further speed up and improve the accuracy of intermittent coating. When the liquid is held in the discharge nozzle so as to face the electrode and a potential difference is provided between the liquid in the discharge nozzle and the electrode, the liquid in the discharge nozzle is charged and the charged liquid is discharged between the discharge nozzle and the electrode. Due to the action of the generated electric field, the effect of being sucked in the direction of the electrode and flying is obtained. In FIG. 9, reference numeral 300 denotes a bias electrode provided at the tip of the downstream discharge nozzle 27, 301
Is a control electrode provided in the upstream discharge nozzle. By utilizing both the air flow and the electrostatic force, it is possible to draw out the liquid by the voltage applied between both electrodes and further accelerate it by the air flow to effectively fly the liquid.

In the present invention, since the positive displacement micro snake pump is used, it is possible to easily discharge the high-viscosity fluid, which was difficult with the conventional ink jet system.

As an auxiliary function of liquid ejection, an ink jet type heater may be provided instead of the electrodes.

[0040]

EFFECTS OF THE INVENTION According to the present invention, the original characteristics of the snake pump, that is, it is suitable for transporting a high-viscosity fluid, the discharge flow rate is hardly affected by changes in environmental conditions such as temperature (viscosity change), etc. It is possible to realize a high-speed, high-precision intermittent discharge device having many features that could not be realized by the conventional snake pump system or the air pulse system without losing the above.

When the present invention is used, for example, as a dispenser in the field of surface mounting, it can make full use of its excellent features in response to demands for high-speed mounting, miniaturization, and high quality of mounting, and the effect is great. is there.

[Brief description of drawings]

FIG. 1 is a front sectional view showing a first embodiment of the present invention.

FIG. 2 is an enlarged view of the nozzle tip.

FIG. 3 is a diagram showing a driving principle of a snake pump used in this embodiment.

FIG. 4 is a block diagram of a swing motion control unit according to the present invention.

FIG. 5 is a block diagram showing the entire control circuit of the present invention.

FIG. 6 is a front sectional view showing a second application example of the present invention.

FIG. 7 is a view showing a radial direction regulating means of a second embodiment.

FIG. 8 is an enlarged view of a discharge portion of the third embodiment.

FIG. 9: Principle diagram of a conventional levitating rotary motor

FIG. 10 is a front sectional view of a known snake pump.

FIG. 11 is a configuration diagram showing an air pulse dispenser.

[Explanation of symbols]

 10 Spindle 11 Rotor 12 Stator 23 Suction Hole 27 Discharge Nozzle 28 Rotor

Claims (7)

[Claims] 1. A liquid transporting portion formed between a liquid suction hole and a discharge nozzle, a rotor and a fixing member that houses the rotor, a shaft connected to the rotor, and a space between the shaft and the fixing member. In a liquid supply device, the liquid supply device is provided with a means for imparting a relative rotational movement and a swinging movement to each other, and a control unit which is a drive power source for the liquid supply nozzle. A fluid supply device comprising: a compressed gas discharge part that assists the discharge action of the liquid in conjunction with discharge from the liquid; and a supply source that supplies the compressed gas to the discharge part. 2. The fluid supply device according to claim 1, wherein the fluid transport section is a uniaxial eccentric screw pump. 3. A rotary actuator for imparting a relative rotary motion between the shaft and the fixing member, a rotary motion control section which is a driving power source for the rotary actuator, and a rotary actuator between the shaft and the fixing member. 3. The fluid supply device according to claim 2, wherein the fluid supply device comprises an oscillating actuator for giving an oscillating motion, and an oscillating motion control section which is a driving power source for the oscillating actuator. 4. The rotary motion control unit and the rocking motion control unit are synchronously controlled so that the rotary motion and the rocking motion are combined and a regular revolution motion is performed. The fluid supply device described. 5. The fluid supply device according to claim 3, wherein the swing actuator is a magnetic bearing. 6. The fluid supply apparatus according to claim 1, wherein the rotary actuator and the swing actuator are provided with the same motor. 7. The discharge nozzle or the compressed gas discharge part is provided with an electrode for electrostatic suction or charge control or a heater for a bubble jet, and is interlocked with the discharge of the liquid from the liquid transport part. The fluid supply device according to claim 1, wherein the fluid supply device is configured to operate the electrode, the heater, or the like.