JPH05138087A - Coating flow control device - Google Patents

Abstract

PURPOSE:To detect the presence of bubbles in a tube and thereby make a paint ed film uniform by forming a constitution where a coating feed means is con trolled by 'feed forward' action without activating a feed back, if a bubble detection signal is output from a bubble detection means. CONSTITUTION:If a coating in a tube 8 contains no bubbles, it is entirely liquid or semi-kneaded, so that almost no volume change takes place under pressure. On the other hand, if the coating contains bubbles, the gas changes its volume significantly under pressure, and subsequently, only the volume of coating equal to reduction in the volume due to pressure flows in, resulting in the generation of a comparatively large flow in a flow meter 3. Thus the presence of bubbles in the tube 8 is determined by detecting a difference in the flow. Activating the detection of bubbles is performed prior to the initiation of coating a next work, as said action operates valves 5a, 6a. If the presence of bubbles is detected, the flow meter 3 is rendered impossible to measure accurately, and subsequently, the flow of coating is controlled only by a feed forward action instead of a feed back action.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a paint flow rate control device, and is applied to a paint supply device for a painting robot or the like used for painting automobiles, household electric appliances, furniture, etc., which require particularly high painting quality. Coating material flow control device.

[0002]

2. Description of the Related Art Due to recent advances in electronics technology, industrial robots have become popular. In the field of coating, automation is being promoted for the purpose of environmental improvement, labor saving, and improvement of coating quality.

In the automation of the painting, a high degree of workability of the painting robot relating to the actual painting is required, and a high flow rate control performance of the paint feeding device for feeding the paint to the painting robot is required.

A paint flow rate control device disclosed in Japanese Patent Application Laid-Open No. 3-25514 has been proposed in response to such a demand. This paint flow rate control device uses a mass flowmeter as a flowmeter for comparing and measuring the paint flowrate, and improves the accuracy of flowrate measurement by providing a timer corresponding to the response delay time of the flowmeter. Further, the control for this delay time is performed based on the stored value of the control signal in the previous painting operation, thereby realizing highly accurate flow rate control.

[0005]

However, in the conventional paint supply device, the flow meter is inaccurately measured due to the inclusion of air bubbles in the paint tube for supplying the paint, and the uniformity of the coating film is deteriorated. There were cases. Also, when feedback control is performed during flow rate control for a short-term intermittent command flow rate, water hammer due to paint in the tube and expansion and contraction of the resin tube cause inaccurate measurement of the flow meter and mass flow meter. Due to the delay in measurement, the flow rate control became unstable, and hunting or overshoot sometimes occurred. For example, although the flow rate is actually zero, a small amount of paint flows to the flow meter in a short time due to the expansion of the resin tube, so that a flow rate signal is output and the response of the flow rate measurement is poor. Furthermore, since control is performed by changing the rotational speed of the pump based on the flow rate signal that is output with a delay relative to the actual flow rate change, in extreme cases, the flow rate control pump can be reversed to remove the paint. There is a possibility that the phenomenon of pumping in the reverse direction may occur.

The present invention has been made in view of the above problems, and avoids a delay in response in flow rate control, detects air bubble mixing in a tube to achieve uniformity of a coating film, and provides a short-term intermittent command flow rate. It is an object of the present invention to provide a paint flow rate control device that can perform stable flow rate control.

[0007]

The invention according to claim 1 is
Paint delivery means for delivering the pressurized paint, a paint pipeline for supplying the paint delivered by the paint delivery means to a coating gun, and the interior of the paint pipeline provided in the paint pipeline A flow rate measuring means for measuring the flow rate of the paint, a feedforward operation for forming a control signal according to a flow rate value of a preset command flow rate, and a flow rate value of the command flow rate and a flow rate measurement value from the flow rate measuring means. A control means for supplying a control signal to the paint delivery means by a feedback operation for forming a control signal based on the difference to control the flow rate of the paint supplied through the paint conduit, and the inclusion of air bubbles in the paint conduit. And a bubble detection unit that outputs a bubble detection signal to the control unit when the mixture of air bubbles is detected, and the control unit outputs the bubble detection signal from the bubble detection unit. The feedforward operation without performing the feedback operation when it is characterized in that it comprises a structure for controlling the paint delivery means.

According to a second aspect of the invention, the control means comprises:
A zero cut means for outputting a zero cut command for controlling the paint delivery means so that the flow rate of the paint in the paint pipe becomes zero when the flow rate of the command flow rate is below a predetermined value. It is characterized by

According to a third aspect of the invention, the control means comprises:
A storage unit that stores an error signal that is a difference between the flow rate value of the command flow rate and the flow rate measurement value output from the flow rate measurement unit, and a flow rate value of the command flow rate based on the error signal stored in the storage unit. And a correction means for outputting a correction signal for correcting

According to a fourth aspect of the present invention, the bubble detecting means is provided in two valves provided in a predetermined portion in the paint pipeline and in a portion of the paint pipeline isolated by the two valves. Bubble mixture determining means for determining that bubbles are mixed in the paint pipe when a predetermined flow rate signal is output from the flow rate measuring means when the paint sent out through the flow rate measuring means is supplied. It is characterized by having and.

[0011]

According to the first aspect of the present invention, by providing the control means for controlling the flow rate by the feedback operation and the feedforward operation, the hunting, the overshoot, etc. which occur only in the feedback operation are reduced, and the feedforward operation is performed. It is possible to eliminate the steady error that occurs in the case of only. Further, since the control unit does not perform the feedback operation when the bubbles are mixed in the paint pipe, the erroneous flow rate signal of the flow rate measuring unit caused by the bubbles does not affect the flow rate control.

According to the second aspect of the present invention, the zero cut means cuts off the command flow rate equal to or less than the predetermined flow rate value.

According to the third aspect of the invention, the flow rate control signal is corrected by the correction signal from the correction means, so that the flow rate control is performed in consideration of the past actual flow rate.

According to the fourth aspect of the present invention, when air bubbles are mixed in a predetermined portion in the paint pipe, the volume of the air bubbles is compressed by supplying the pressurized paint, so that the predetermined flow rate signal is output from the flow rate measuring means. Is output.

[0015]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a system diagram of a paint flow rate control apparatus according to an embodiment of the present invention. The paint flow rate control device shown in FIG. 1 includes a color change valve 1 for switching paint colors or a thinner for cleaning and paint, cleaning air, a regulator 2a for setting the flow rate and pressure of fluid, and a Coriolis mass. A flow meter 3 (a flow rate measuring means) configured to measure an instantaneous flow rate and an integrated flow rate of a fluid, a gear pump 4a (a paint delivery means) for feeding paint at a pressure corresponding to the flow rate, and an opening / closing by supplying an air signal. Valve 5
A paint gun 7 for spraying a, 6a and paint onto the object to be painted is connected by a paint tube 8 (the paint conduit).

Further, the paint flow rate control device includes a converter 2b,
A control circuit 9 (the control means) for controlling the regulator 2a and the valves 5a, 6a through the controllers 5b and 6b and the controller 4b, and a memory 1 connected to the control circuit 9.
0 (storage means), a residual bubble determination circuit 11 (bubble inclusion determination means) and a zero cut circuit 12 (zero cut means).

The valve 6a provided at the tip of the tube 8 is referred to as a trigger valve, and is provided for the purpose of preventing the elasticity of the tube 8 from deteriorating the rise at the time of spraying the paint and the break at the time of the stop. Has been. Further, the valve 6a is actually built in the coating gun 7, and is shown adjacent to the coating gun in FIG. 1 for convenience of explanation.

In the paint flow rate control device having the above structure, the paint, thinner or air of each color supplied to the color change valve 1 is color-changed by the control of the control circuit 9 which is supplied with the command signal by the setting of the host computer (not shown). It is properly selected by the valve 1. Further, the flow rate and pressure of paint and the like are set by the regulator 2a, and the flow rate is measured by the flow meter 3. Further, fine flow rate control is performed by controlling the rotation speed of the gear pump 4a, and the paint is sent to the coating gun 7 by opening the valves 5a and 6a. The tube 8 to which the paint, thinner and the like are conveyed is generally made of a flexible resin such as Teflon so that the coating gun 7 can easily move according to the coating location.

A control circuit 9 according to the flow rate signal from the flow meter 3
Thus, the regulator 2a or the gear pump 4a is controlled. As the regulator 2a, a so-called air-operated regulator used for controlling the flow rate of a general paint is used, but the regulator 2a is not limited to this, and an electric control valve may be used.

The converters 2b, 5b and 6b are for converting the electric signals output from the control circuit 9 into air signals. For example, 4 to 20 mA electric signal 0 to 2 kg / cm
Convert to ² air signal. However, the converter 6b may be a simple electromagnetic valve, and the pressure of the air may be turned on and off by opening and closing the electromagnetic valve.

FIG. 2 is a perspective view of a painting robot apparatus to which the paint flow rate control apparatus according to one embodiment of the present invention is applied.
In the figure, a work 21 as an object to be coated is a conveyor device 2.
In the coating process that is conveyed in the direction of arrow X by 2,
A painting robot 23 is installed in the vicinity of the conveyor device 22, and each moving part of the painting robot 23 is drive-controlled by a control device 38, and a predetermined teaching that has been taught while the work 21 passes through a painting work position. Perform the painting work of.

In FIG. 2, a turning drive unit 25 is provided on the base 24. A swivel base 26 is provided on the swivel drive unit 25 to rotate around an axis A fixed to the base 4. A bracket 26 a on the swivel base 26 is provided with a first arm 27 that rotates about an axis B orthogonal to the axis A of the swivel base 26. In addition, the bracket 6a on the swivel base 26
The first arm drive unit 28 is provided in the.

At the upper end of the first arm 27, the first arm 27
A second arm 29 that rotates about an axis C parallel to the axis B of the arm 27 is rotatably provided. A second arm driving unit 30 is provided at a connecting portion between the second arm 29 and the first arm 27. Also, the second arm 2
A wrist drive unit 31 is provided at the rear of the unit 9. Further, a wrist mechanism 32 is provided at the tip of the second arm 29. The wrist mechanism 32 is provided with cases 33 and 34 and a mounting shaft 35. The case 33 is configured to rotate about an axis D parallel to the axis C of the first arm 29. The case 34 is configured to rotate about an axis E orthogonal to the axis D of the case 33.
The mounting shaft 35 is a mounting portion of the coating gun 7, and is provided with a case 34.
It rotates around an axis F that is orthogonal to the axis E.

The coating gun 7 sprays the paint by the above-mentioned mechanism while freely moving according to the teaching data inputted in advance, and sprays the paint having a predetermined color onto the work 21.

FIG. 3 is a block diagram of the command portion of the control circuit 9 shown in FIG. The command portion in the figure is entirely configured by a microcomputer called a sequencer. In the figure, reference numeral 41 designates a microprocessor, which instructs the type of fluid such as paint and thinner and the flow velocity from a host computer (not shown), and outputs a flow velocity command signal via the digital-analog converter 42 in accordance with the parallel input / output. A zero cut signal, a feedback on / off signal, an integrator on / off signal, and a valve control signal, which will be described later, are output via the ports 43 and 44.

FIG. 4 shows a circuit block diagram of the flow velocity control circuit in the control circuit 9. In the figure, the flow velocity command signal is amplified by the amplifier 46 and added by the adder 47 with the feedback signal supplied via the switch 48. Further, the output of the rotation speed detector 50 is subtracted from this signal by the subtracter 49 via the switch 51, and is supplied to the servo motor 53 corresponding to the controller 4b of FIG. The servomotor 53 drives the gear pump 4a according to this signal. The output of the servo motor 53 is detected by the rotation speed detector 50 and fed back to the subtractor 49. By this feedback operation, the operation of the gear pump 4a is accurately controlled.

Further, a small flow rate of a predetermined value or less by the zero cut signal supplied from the parallel input / output port 43 of FIG.
That is, for the flow velocity command signal corresponding to the flow rate in the zero cut region (for example, 20% of full scale), the servo motor 5
3 is controlled not to operate. The signal amplified by the amplifier 46 is delayed by the delay device 54 by a time equal to the operation delay time of the flowmeter 3 and supplied to the subtractor 55. In addition, the flow rate value supplied from the flow meter 3 is converted into a flow rate value and is subtracted as a flow rate detection signal of an analog signal by the subtractor 55.
Is supplied to.

Here, the flow velocity detection signal is subtracted from the flow velocity command signal output from the delay device 54 to generate a difference between the command flow velocity and the actual flow velocity value, that is, an error signal. This delay device 5
Since the delay time is equal to the operation delay time of the flow meter 3 in 4, the flow rate of the paint is controlled by the flow rate command signal via the gear pump 4a, and the result is detected and fed back by the flow meter 3, especially The error due to the time delay due to the operation delay of the flow meter 3 is removed.

The error signal from the subtractor 55 is sent to the amplifier 5
It is supplied to the adder 47 via 6 and the switch 48.
Here, the flow velocity command signal directly supplied via the amplifier 46 and the error signal are added, whereby the flow velocity command signal is corrected by the error signal.

Further, when a feedback on / off signal is output from the parallel input / output port 43 or a bubble detection output is output from the flowmeter 3, the switch 48 is opened by the output from the OR circuit 59. However, the flow rate command signal is not corrected by the error signal. Therefore, the flow rate detection signal from the flow meter 3 in a state where correct measurement cannot be performed due to inclusion of bubbles is not used for feedback control, and the feedback control is prevented from being disturbed by an erroneous flow rate detection signal. The flowmeter 3 of the mass flowmeter has a gas-liquid discrimination output circuit 3a for detecting bubbles by detecting the amplitude of the sensor tube. From the gas-liquid discrimination output circuit 3a, the bubble detection output is ORed. It is output to 59.

When a flow rate integration ON / OFF signal is supplied from the parallel input / output port 43, the switch 57 is closed, and the pulsed flow rate output from the flow meter 3 is output by the integrator 5.
It is supplied to 8 and integrated.

As described above, the flow control circuit having the above-described structure eliminates the adverse effect of the inaccurate measurement value of the flow meter due to the operation delay of the flow meter 3 and the inclusion of bubbles, and the accurate flow control can be realized. ..

FIG. 5 shows a time chart of the operation pattern of the paint flow rate control device when the work 21 of FIG. 2 is painted. As shown in the figure, at the time of painting on the work, the feedback on / off signal is supplied and the flow rate integrated on / off signal is supplied. In addition, at the time of color change, the paint 1 of the previously used color is supplied and then thinner and air are alternately supplied to clean the passage of the paint, and then the paint 2 to be used next is supplied. During such a color change, neither the feedback on / off signal, the flow rate integrated on / off signal, nor the zero cut signal is output, and the flow rate control for thinner, air, etc. is not performed.

FIG. 6 shows a modification in which the feedback loop portion of the amplifiers 46 and 52, the delay device 54, the subtractor 55, the switch 48, and the adder 47 of FIG. 4 is configured by a microcomputer. Further, FIG. 7 shows a diagram of the operation time chart of FIG. In the figure, the trigger valve signal TV
Is a signal for opening the valve 6a in FIG.
Further, the mass flow velocity command signal FC corresponds to the flow velocity command signal of FIG.

The microprocessor 61 issues a selection signal to the multiplexer 62 by the function of the timer 61d. The mass flow rate command signal FC and the mass flow rate feedback signal FB supplied to the multiplexer 61 are selected by the multiplexer 62 which receives the selection signal issued from the microprocessor 62 at every sampling time T _S , and both are at each sampling time T _S. To the microprocessor 62. In this way, the signals FC and FB are sampled by the microprocessor 61 at the sampling time T _S.

The mass flow rate command signal FC is supplied to the feedback loop having the above-mentioned structure with a slight delay from the time point τ _V when the trigger valve signal TV is supplied. Time τ when the mass flow velocity designation signal FC exceeds the zero cut region
After the delay time τ _FB of the flow meter 3 has elapsed from _FF, sampling of the mass flow rate command signal FC and the mass flow rate feedback signal FB corresponding to the flow rate detection signal of FIG. This sampling is continued until the time of the fall.

The signals FC and FB sampled by the microprocessor 61 are supplied to the analog / digital converter 61a. Each signal FC converted into a digital value by the analog / digital converter 61a,
FB is the difference between the two in the microprocessor 61,
That is, the error signal is calculated. Further, the microprocessor 61 internally has a zero cut function corresponding to the zero cut means, and when the error signal is a minute value equal to or less than a predetermined value, the value is forcibly set to zero. This prevents erroneous control due to measurement error of the flow meter. That is, for example, the resin tube 8 swells instantaneously due to the pressure of the fluid, and although the flow rate is actually zero, a small amount of the mass flow velocity feedback signal FB is supplied from the flow meter 3, and the mass flow velocity command signal is thereby generated. When a difference with FC is generated, if it is small, it is forcibly set to zero, and erroneous correction is prevented.

Further, this error signal is temporarily stored in the memory 61c corresponding to the storage means, and the average of a predetermined time (for example, averaging four sample values) is calculated by the function corresponding to the correction means. .. The average value of the error signal is converted into an analog value via the digital / analog converter 61b at each sample time T _S and is output as a signal corresponding to the correction signal. Further, this output value is added to the adder 6
In step 3, the mass flow rate command signal FC is added and the corrected mass flow rate command signal is output. The corrected mass flow velocity command signal is used as a flow velocity command signal by the servo motor 51.
Is supplied to. The above configuration corresponds to the correction means, delays the operation delay time of the flow meter 3, compares the mass flow rate feedback signal FB with the mass flow rate command signal FC, and calculates the error signal of the difference between them. Further, the error signal of the past is stored in the memory 6
1c, and the average of them is taken and added as a correction signal to the mass flow rate command signal. By performing such control, sampling is started after the delay time τ _FB of the flow meter has elapsed even when a short intermittent flow rate is supplied, so that the accurate command signal FC and the feedback signal FB are compared. Is possible. Further, since the command signal FC is sequentially corrected by the average value of the error signals calculated by this comparison, highly accurate flow rate control becomes possible.

FIGS. 8A, 8B and 8C are time charts showing the response of the control circuit having the configuration shown in the block diagram of FIG. As described above, in the present embodiment, the flow rate is controlled by the gear pump 4a. In this case, the servomotor 5 that drives the gear pump 4a is used.
The response delay time of 1 is about 20 msec, whereas the response delay of the flowmeter 3 is about 100 msec, which is a relatively large value.

For this reason, in this embodiment, a feedforward, which is a response delay time of 20 msec of the servomotor 4a, that is, an open loop control system is applied to the response, and a steady error is avoided in the control accuracy. By applying a feedback control method that can be applied, both advantages are achieved.

FIG. 8A shows the response when feedback is not applied, that is, when the switch S _{1 in} FIG. 4 is in the open state. This is the case where the control method is applied by the above feedforward. In this case, the actual flow velocity FA rises with a delay of 20 msec of the response delay time of the servo motor 4a with respect to the pulsed command signal FC, and further, the flow velocity conversion value FD of the output of the flowmeter gradually rises. Here, in the case of feedforward control, since there is no feedback of the output result, a steady error EC occurs due to wear of the blades of the gear pump 4a, variation in the viscosity of the fluid, or the like.

On the other hand, in the case of only the feedback control shown in FIG. 8B, the loop gain of the feedback loop needs to be increased in order to obtain sufficient control accuracy. Since the response delay is large, overshoot and hunting occur as shown in the figure.

By applying the control circuit having the configuration shown in FIG. 6 to these, as shown in FIG. 8C, the rising edge is fast, that is, the responsiveness is good, and the command signal FC can be output without overshoot. It is possible to perform highly precise control that follows. This is because the command signal FC is compared with the flow velocity detection signal FD supplied from the flow meter 3, that is, the feedback signal FB after the lapse of the response delay τ _FB by the flow meter 3 described above, and the resulting error signal is errored. This is performed by adopting a configuration in which the signal is amplified by an amplifier and added to a feedforward circuit as a correction signal.

Although it has been described here that the configuration related to the feedback loop of the flow rate control circuit is realized by the microcomputer, the configuration is not limited to this, and the entire configuration shown in FIGS. 3 and 4, and further for coating in FIG. Needless to say, it can be realized by a microcomputer including control of the robot.

The air bubbles in the tube 8 are detected by the gas-liquid discrimination output circuit 3a of the flowmeter 3 as described above.
Apart from this, there is a method of detecting by the operation of the valves 5a and 6a and the change of the flow rate detection output of the flow meter 3. FIG. 9 (A)
Shows the relationship between the flowmeter 3, the valves 5a and 6a, and the tubes 8a and 8b in FIG.

Further, FIGS. 9B, 9C and 9D respectively show a state where the coating operation is completed and only the valve 6a is closed, a state where only the valve 6a is closed, and a valve. A tube 8a between the flow meter 3 and the valve 5a in each state in which 6a is closed and the valve 5a is opened.
The changes in the internal pressure and the internal pressure of the tube 8b between the valve 5a and the valve 6a are shown. Residual bubbles are detected by operating the valves 5a and 6a so as to sequentially realize the above states (B) to (D).

FIG. 10 shows a time chart of the operation of the valves 5a and 6a and the flow rate measurement output value of the flow meter 3 which changes accordingly. That is, only the valve 6a of FIG. 9B is closed, and the paint in the tube 8a is pressed between them. In the state B to (C), the valve 5a is first closed, and then the valve 6a is opened. During that time, the paint in the tube 8a is in a non-pressurized state C, and the valve 6a in (D) is closed and then the valve 5a is opened to pressurize the paint in the tube 8a again. The state changes to D.

Here, the tube 8a between the two valves 5a and 6a is once brought into a non-pressurized state when shifting from the state B to the state C, and again brought into a pressurized state when shifting from the state C to the state D. Therefore, at this time, when the paint in the tube 8a does not contain air bubbles, the paint is almost liquid or semi-torsional, so that the volume hardly changes due to pressurization. Therefore, the flow rate of the flow meter 3 in FIG. 10 hardly flows as indicated by Q ₂ , and the flow rate becomes almost zero.

On the other hand, in the case of containing air bubbles, the volume of the gas largely changes due to pressurization, so that the paint flows in as much as the volume is reduced by pressurization, and a relatively large flow rate is generated as indicated by Q _1. .. Bubbles in the tube 8 can be detected by detecting the difference between the flow rates of Q ₁ and Q ₂ .

The bubble detecting operation is performed by the valve 5a,
Since 6a is opened and closed, this is performed before the next coating of the work 21 is started. If air bubbles are detected here, the flow meter 3
Since the measurement of is inaccurate, the paint flow rate is controlled only by the feedforward operation without performing the feedback operation.

Further, it goes without saying that each circuit configuration in the control circuit 9 is not limited to the configuration shown in this embodiment, and may be another circuit configuration having substantially the same function.

Although the flow rate is controlled by controlling the rotation speed of the gear pump 4a in the present embodiment, the flow rate may be controlled by applying a flow rate adjusting valve or the like without being limited to this configuration.

[0053]

As described above, according to the first aspect of the present invention, there are advantages of both good response of the feedforward operation and controllability of the feedback operation with high accuracy, and hunting of the flow rate by the feedback control, Since there is no overshoot, the water hammer of the pipeline and the expansion and contraction of the resin pipeline do not occur even when painting is performed intermittently, and feedback operation is performed when bubbles are detected in the pipeline. Since this is not done, an error in the flow rate measurement value caused by the inclusion of bubbles can be removed, and highly accurate flow rate control can be realized.

According to the second aspect of the invention, since the flow rate control is prevented from becoming unstable with respect to the command flow rate of the minute flow rate, the minute flow rate generated by the expansion and contraction of the resin pipe line or the like. Also, the flow rate control is not adversely affected, and stable flow rate control can be performed.

According to the third aspect of the present invention, the command flow rate is constantly corrected by the correction means in accordance with the actual flow rate performance, so that stable flow rate control can be performed even for short-term intermittent command flow rates. It can be done.

According to the invention as set forth in claim 4, since it is possible to reliably detect the bubbles in the pipe line with a simple structure, erroneous control due to the bubbles is prevented and highly accurate flow rate control is realized. it can.

[Brief description of drawings]

FIG. 1 is a system diagram of an embodiment of the present invention.

FIG. 2 is a perspective view of a main part of the painting robot according to the embodiment of the present invention.

3 is a block diagram of the control circuit of FIG. 1. FIG.

FIG. 4 is a circuit block diagram of a flow rate control circuit in the control circuit of FIG.

FIG. 5 is a diagram showing an operation time chart of one embodiment of the present invention.

FIG. 6 is a circuit block diagram of a flow rate control circuit of another embodiment of the control circuit of FIG.

FIG. 7 is a diagram showing an operation time chart of FIG. 6;

FIG. 8 is a time chart showing the response of FIG.

FIG. 9 is a diagram illustrating an operation of detecting bubbles.

FIG. 10 is a diagram of an operation time chart of FIG. 9;

[Explanation of symbols]

 3 flow meter (flow rate measuring means) 4a gear pump (paint delivery means) 5a, 6a valve (pressurized paint supply means) 8 tube (paint line) 9 control circuit (control means) 10 memory (memory means) 11 residual bubble discrimination Circuit (Air bubble inclusion judgment means) 12 Zero cut circuit (Zero cut means)

 ─────────────────────────────────────────────────── ─── Continuation of front page (72) Inventor Junichi Ikeda 1-3-6 Fujimi, Kawasaki-ku, Kawasaki-shi, Kanagawa Tokiko Corporation (72) Makoto Nishimura 1-3-6 Fujimi, Kawasaki-ku, Kawasaki-shi, Kanagawa Issue Tokiko Co., Ltd.

Claims (4)

[Claims] 1. A paint delivery means for delivering pressurized paint, a paint pipeline for supplying the paint delivered by the paint delivery means to a coating gun, and an interior of the paint pipeline provided in the paint pipeline. Flow rate measuring means for measuring the flow rate of the paint to be fed, a feedforward operation for forming a control signal according to the flow rate value of the preset command flow rate, and the flow rate value of the command flow rate and the flow rate measuring means from the flow rate measuring means. Control means for supplying a control signal to the paint delivery means by a feedback operation for forming a control signal based on a difference from the flow rate measurement value and controlling the flow rate of the paint supplied through the paint pipe line; And a bubble detection unit that outputs a bubble detection signal to the control unit when detecting the inclusion of bubbles in the road, and the control unit receives the bubble detection signal from the bubble detection unit. Out Paint flow control device, wherein said by the feed-forward operation without performing a feedback operation to become a structure for controlling the paint delivery means when it is. 2. The control means issues a zero cut command for controlling the paint delivery means so that the flow rate of the paint in the paint conduit becomes zero when the command flow rate is equal to or less than a predetermined value. The paint flow rate control device according to claim 1, further comprising a zero-cut means for outputting. 3. The storage means for storing an error signal, which is a difference between a flow rate value of the commanded flow rate and a flow rate measurement value output from the flow rate measurement means, and an error stored in the storage means. The paint flow rate control device according to claim 1, further comprising a correction unit that outputs a correction signal that corrects the flow rate value of the command flow rate based on a signal. 4. The bubble detecting means includes two valves provided at a predetermined portion in the paint pipeline, and the flow rate measuring means at a portion of the paint pipeline separated by the two valves. And a bubble mixture judging means for judging that bubbles are mixed in the paint pipe when a predetermined flow rate signal is outputted from the flow measuring means when the paint sent out is supplied. The paint flow rate control device according to claim 1, wherein: