JPH07308619A - Fluid feed device - Google Patents

Abstract

PURPOSE:To provide a fluid feed device which has pulsation-free continuous flux characteristics and constant flux characteristics independent of environmental conditions, and further, ensures super-high precision and super-micro flow feed. CONSTITUTION:A fluid feed device consists of a fluid suction hole 23 and a fluid discharge hole 27, a fluid transport part formed between a rotor 25 and a fixed member 19 for storing this rotor 25, a shaft 10 connected to the rotor, a rotary actuator 35 for giving a relative rotating motion to the shaft 10 between the shaft 10 and the fixed member, and a rotating motion control part which is a drive power supply for the actuator. In addition, the device is composed of a fluctuation actuator 31 for giving a relative fluctuation motion to the rotary member between the rotary member and the fixed member, and a fluctuation motion control part which is a drive power supply for the actuator 31. Thus it is possible to ensure the super-high precision and super-micro feed flux of a fluid under a simple structure.

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, clean 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, fluid materials can be made highly accurate and stable. The technology to control it is being demanded.

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 device, an air pulse type dispenser as shown in FIG. 12 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. 11 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, 104 and 105 are universal joints, and rotor 102 and coupling rod 106
Also, the coupling rod 106 and the drive shaft 100 are connected. 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 1
02 moves up and down while rotating inside the stator 103. The fluid contained between the rotor 102 and the stator 103 is continuously sent out from the suction side to the discharge side by an infinite piston movement without breaks.

[0006]

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 viscosity of liquid 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] Problem 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 are provided as compared with the above air pulse type dispenser. It has a constant flow rate characteristic that is unlikely to be affected by changes in the load on the discharge side. However, inside the stator 103, the rotor 10
This type of pump, in which a pumping action is obtained by performing a reciprocating linear motion while the 2 rotates, is a rotor 102.
Is basically a cantilever support structure, and the stator 103 also functions as a bearing for supporting the rotor 102.
Therefore, for example, when the rotation speed of the main shaft 100 is increased or the pressure on the discharge side is increased due to an increase in the load of the pump, the motion of the rotor 102 that does not have a sufficient positioning and holding function is likely to be unstable. As a result, the clearance between the rotor 102 and the stator 103 fluctuates, and the internal leak amount 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 snake pump is used as a dispenser, when the rotor has a smaller diameter, the accuracy of the total discharge flow rate is limited to ± 10 to 20% at most due to the reason described above. Also,
Ultra-small flow rate of dispenser (eg Q = 10 ^-5 cm
³ / sec or less), for example, rotor diameter:
If you tried to reduce the diameter to less than D = 0.5 mmφ,
In the conventional structure involving metal-to-metal contact between the stators, elastic deformation, sliding wear, damage, etc. occur due to the reduction in strength of the rotor.
Practical application was extremely difficult.

[0011]

In order to solve the above-mentioned problems, in a fluid supply apparatus according to the present invention, it is formed between a fluid suction hole and a fluid discharge hole, and a rotor and a fixing member for accommodating the rotor. Fluid transport part, a shaft connected to the rotor, a rotary actuator for providing a relative rotary motion between the shaft and the fixed member, a rotary motion control part which is a driving power source for the rotary actuator, and the shaft. A swing actuator for providing relative swing motion between the sleeves,
It is characterized in that it is composed of a swing motion control section which is the drive power source.

[0012]

The snake pump which is the object of the present invention has a sectional length of
To reciprocate the rotor linearly inside the circular stator
Eccentric movement of the drive side main shaft connected to this rotor
At the center of the eccentric shaft while making (oscillating motion)
It is intended to rotate. Figure 1 shows the movement of the snake pump
It shows the working principle, 1 is the basic circle, 2 is the inscribed circle
It O₁Is the center of the inscribed circle 2 and O₂Is the eccentric motion of the rotor
The center of 3 and O is 3₁Is the main axis around. here
The inscribed circle 2 rolls inside the basic circle 1 at the rotation speed ω
When rotated from the center O₁Is the center O₂Spinning around
It oscillates at a number ω. So the main axis of the snake pump
3 is center O while rotating at the rotation speed ω ₂Eccentric around
The amount of ε will cause oscillating motion.

The rotor (not shown in FIG. 1; 25 in FIG. 2) of the pump portion for transporting the fluid is a true circle centered on the circumference of the inscribed circle 2. This rotor is housed in a stator (not shown in FIG. 1; 26 in FIG. 2) having an oval cross section, and makes a linear motion passing through the origin O ₂ .

In the fluid supply device to which the present invention is applied, the main shaft 3 is simultaneously given a swinging motion and a rotary motion 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.

It should be noted that, in the case of a minute flow rate dispenser having an extremely small discharge flow rate, the rotor diameter of the snake pump and the eccentric amount of the swinging motion (ε in FIG. 1) may be extremely small. In this case, as the swing actuator, it is possible to apply a magnetic bearing, a piezo actuator or the like that can obtain a displacement of, for example, about 0.1 to 0.5 mm.

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.

[0017]

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. 2, 10 is a main shaft, 11 is a rotor of a motor which is a rotary actuator, 12 is a stator of a motor, 13 to 19 are fixing members, and 20 and 21 are fixing members 13, 14, 15, and 1.
6, 17, 18, 19 and the upper thrust fluid bearing and the lower thrust fluid bearing formed between the main shaft 10, 22 is a flange-shaped seal portion, 23 is a suction hole, and 24 is the main shaft 10.
The screw groove pump formed in the above, 25 is a snake pump rotor, 26 is a snake pump stator, and 27 is a 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 an oscillating 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 orthogonally 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 constituted. 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. In addition, the rotor 11, the stator 12,
The rotor 32 and the stator 33 constitute a rotary actuator 35 that regularly rotates the main shaft 10 based on the rotational position information obtained by the encoder. FIG. 3 shows a block diagram of the swing motion control unit 81 that drives the magnetic bearing actuator 31. In the swing motion control section 81, each shaft of the magnetic bearing is driven in synchronization with the rotary motion. A structural model of a magnetic bearing is shown in the drawing, and the stator 29 is composed of 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. 4 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, the swing motion control section 81 sends the pulse train obtained from the rotation signal generator 82 to the X-axis and Y-axis signal processing section (FIG. 3) 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. Figure 2
In the above, the thrust fluid bearings 20 and 21 are known dynamic pressure bearings in which a shallow groove 32, which is commonly called a herringbone (fish bone), is formed on the surface of the brim, and an example of the shape is shown in FIG. Lubricating oils 33 and 34 are enclosed between the fluid bearings 20 and 21 and the fixing members. 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
Since it is supported by 0 and 21, the axial position is regulated without tilting. 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 to prevent the transport fluid from invading the fluid bearing portion and the magnetic bearing portion, and the clearance between the collar and the axially opposed surface 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.

In the conventional snake pump using the universal joint (FIG. 11), if there is a clearance between the rotor 102 and the stator 103, the rotor 102 floats within the clearance range. As a result, the amount of internal leak fluctuates under the influence of the unstable behavior of the rotor 102, causing variation in flow rate accuracy. In the embodiment of FIG. 2 to which the present invention is applied, the movement of the rotor 25 and its absolute position are completely regulated by the main shaft 10 on the upper drive side. Therefore, the rotor 25 having a complicated snake shape can be kept in non-contact with the stator 26 during operation. Rotor 25 in one cycle of motion
Since the movement trajectory of the main shaft 10 is constant, the clearance between the stator 26 and the stator 26 always has a constant synchronous change characteristic at any position. Therefore, the influence 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 as predicted in advance can be obtained.

In the pump of the present invention, there is nothing between the rotor 25 and the main shaft 10 that obstructs the flow of the transport fluid, unlike the conventional universal joints (104 and 105 in FIG. 11). Therefore, even if the snake pump is downsized in order to achieve a minute flow rate and the opening portion 36 at the inlet becomes small,
The transport fluid can smoothly flow into the snake pump.

FIG. 6 shows a second embodiment of the present invention in which a dispenser is constituted by a 5-axis control magnetic bearing and a motor. Reference numeral 50 is a main shaft, 51 is a rotor of a pulse motor which is a rotary actuator, 52 is a stator of the pulse motor, 53 is a fixed sleeve, 54 is a suction hole, 55 is a thread groove pump formed on the main shaft 50, 56 is a snake pump rotor, Reference numeral 57 is a snake pump stator, and 58 is a discharge nozzle. Reference numeral 59 is an upper magnetic bearing rotor, 60 is a stator, 61 is a lower magnetic bearing rotor, 62 is a stator, 63 is a thrust magnetic bearing rotor, and 64a and b are stators. Reference numerals 65, 66 and 67 denote displacement sensors for the upper magnetic bearing, the lower magnetic bearing and the thrust bearing, respectively. Since the main shaft 50 is supported by the two radial bearings and the thrust bearing, it is possible to maintain a completely non-contact state regardless of the operating state or the stationary state.

FIG. 7 shows a third application example of the present invention in which a piezoelectric element is used as a swing actuator.

Reference numeral 150 is a main shaft, 151 is a rotor of a motor which is a rotary actuator, 152 is a stator of the motor, 1
53 is a swing sleeve, 154 is a suction hole, and 155 is the main shaft 1.
Thread groove pump formed on 50, 156 is a snake pump rotor, 157 is a snake pump stator, 158
Is a discharge nozzle. 159 is a fixed sleeve, 160
Reference numerals a and 160b denote piezoelectric actuators 161 and 1 provided between the fixed sleeve 159 and the swing sleeve 153.
Reference numeral 62 is a bearing for supporting the main shaft 150 in the swing sleeve 153. Reference numerals 163 and 164 are guide portions for allowing the swinging sleeve 153 to move only in the radial direction.

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. An application example of the present invention in which a non-contact type snake pump is configured by one actuator (motor) will be described below. Magnetic bearing and motor 2
A levitating rotary motor having two functions at the same time has been studied in the past, and is reported in, for example, Oishi et al., Transactions of the Japan Society of Mechanical Engineers (Vol. 58, No. 556, 1992).
FIG. 10 shows an example of the above report. Reference numeral 200 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 possible that the rotation control and the levitation control do not interfere with each other by combining the permanent magnet rotor and the multi-pole stator and applying the rotating magnetic fields with different phase differences for the rotation control and the levitation control. Proven. (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. 8 shows a fourth application example of the present invention, 20
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 a discharge nozzle, 217 is an upper thrust bearing, 218 is a lower thrust bearing, 219 is a seal portion, 220 is a radial displacement regulating rotor mounted on the main shaft 200, and 221 is 208 and 220.
It is the lubricating oil contained in the gap. The fixing member 208 also has a function as a radial displacement regulation stator. 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 using the above, the radial position of the main spindle 200a 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 reactance motor, an induction motor or the like can be applied.

[0031]

EFFECTS OF THE INVENTION According to the present invention, the pulsating continuous flow rate characteristic originally possessed by the snake pump, the constant flow rate characteristic proportional to the number of revolutions, and the discharge flow rate are less susceptible to environmental conditions such as temperature and viscosity changes. It is possible to realize a fluid supply device having many features that cannot be realized by the conventional snake pump system or the air pulse system without losing the features such as. That is, ultra-high accuracy of flow rate can be achieved, and ultra-fine flow rate can be achieved. Flow rate control range can be expanded. If the present invention is used as a dispenser in the field of surface mounting, for example, in response to demands for high-speed mounting, miniaturization, and high quality of mounting. Therefore, it is possible to take advantage of its excellent features, and the effect is enormous.

[Brief description of drawings]

FIG. 1 is a diagram showing a driving principle of a snake pump which is an object of the present invention.

FIG. 2 is a front sectional view showing a first embodiment of the present invention.

FIG. 3 is a block diagram of a swing motion control unit according to the present invention.

FIG. 4 is a block diagram showing the entire control circuit of the present invention.

FIG. 5 is a diagram showing a thrust fluid bearing.

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

FIG. 7 is a front sectional view showing a third application example of the present invention.

FIG. 8 is a front sectional view showing a fourth application example of the present invention.

9 is a configuration diagram showing a radial displacement restricting portion of FIG.

FIG. 10 is a principle diagram of a known rotary levitation motor.

FIG. 11 is a front sectional view of a known snake pump.

FIG. 12 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 (6)

[Claims] 1. A fluid transport portion formed between a fluid suction hole and a fluid discharge hole, 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. A rotary actuator for providing a relative rotary motion to the shaft, a rotary motion control unit that is a driving power source for the rotary actuator, and a swing actuator for providing a relative swing motion between the shaft and the fixing member, and A fluid supply device comprising a swing motion control unit which is a drive power source. 2. The fluid supply device according to claim 1, wherein the fluid transport section is a uniaxial eccentric screw pump. 3. 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 to perform a regular revolution motion. The fluid supply device described. 4. The fluid supply device according to claim 3, wherein the swing actuator is a magnetic bearing. 5. The fluid supply device according to claim 3, wherein the swing actuator is a piezoelectric element. 6. The fluid supply apparatus according to claim 1, wherein the rotary actuator and the swing actuator are provided with the same motor.