JPH039044Y2 - - Google Patents

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to an apparatus for automatically correcting changes in viscosity due to temperature of a fluid and transferring the fluid at a constant flow rate.

Conventional technology For example, in the painting process, paint is pumped,
This paint is sprayed from a paint gun, but the amount of paint discharged changes due to changes in outside temperature, and the quality of the paint is often unstable. This is because the viscosity of the paint changes depending on the temperature, which changes the pressure loss in piping, etc. Conventionally, known methods for solving this problem include a method of force feeding using a constant displacement pump, a method of controlling the pumping pressure using a flow rate detection device, and a method of controlling the temperature of the entire paint circulation system.

Problems to be Solved by the Invention In all of the above methods, the devices are complicated and expensive, and are not often used as general equipment. Currently, work is being done to make adjustments and stabilize the flow rate.

The present invention attempts to eliminate these drawbacks.

Means for Solving the Problems In order to solve the above-mentioned drawbacks, the present invention, as shown in FIG. a temperature sensor that directly detects temperature and outputs a temperature signal; a memory means that stores temperature-viscosity data of the fluid in advance; and a device that calculates the current fluid viscosity from the data and the temperature signal and uses the calculated value as the value. arithmetic means for outputting a corresponding control signal;
A pressure regulator is provided which adjusts the fluid pressure according to the magnitude of the control signal and continuously transfers the fluid at a constant flow rate.

Operation When the temperature sensor detects the fluid temperature, the calculation means calculates the fluid viscosity at that time from the temperature signal and the temperature-viscosity data stored in the memory means,
The discharge pressure of the fluid to provide a predetermined constant flow rate at this viscosity is calculated, and this is sent to the pressure regulator as a control signal. The pressure regulator adjusts the discharge pressure of the fluid according to a control signal sent from the calculation means. As a result, even if the fluid viscosity changes, the discharge pressure of the fluid is automatically adjusted accordingly, and the fluid is always transferred at a constant flow rate regardless of the change in viscosity.

Embodiments Hereinafter, embodiments of the present invention will be described based on the drawings. FIG. 2 shows an embodiment in which the present invention is applied to a coating device, in which the paint in the paint tank 1 is sucked into the pump 3 via the pipe 2, passes through the pipe 4,
The air is fed under pressure to an air-driven regulator 5, which is a pressure regulator for adjusting the discharge pressure. The paint pressure is regulated by an air-driven regulator 5, and the regulated paint passes through a pipe 6 and is ejected from a paint gun 7, which is a fluid output device. On the other hand, air supplied from the industrial air source 8 passes through piping 9 and enters the electro-pneumatic converter 10 . The electro-pneumatic converter 10 converts the current input of the present invention into air pressure. A current signal input to the electro-pneumatic converter 10 via the wiring 13 is output by the microcomputer 12. Therefore, air pressure corresponding to this current signal is supplied from the electro-pneumatic converter 10 to the air drive regulator 5 through the piping 11. In the air-driven regulator 5, paint is sent to the piping 6 according to the supplied air pressure. To explain the principle, a signal from a temperature sensor 14 that detects the paint temperature is inputted to the microcomputer 12 via a wiring 15. The microcomputer 12 is
From pre-stored temperature-viscosity data,
Wire 13 transmits a current signal to calculate the current viscosity and make the pressure commensurate with the pressure loss of the paint in piping 6 and paint gun 7 when spraying the paint at a certain flow rate.
Output to. In this way, even if the temperature of the paint changes, the flow rate is controlled to be constant.

FIG. 3 shows a detailed circuit example of the microcomputer 12, temperature sensor 14, and electro-pneumatic converter 10, and FIG. 4 shows its flowchart. When the required discharge amount Q is input from the setting device 204, it is stored in the RAM 201 via the digital input port 203 (step S ₁ ), and the temperature signal of the paint is input from the temperature sensor 14 using the resistance temperature detector 207 and the thermometer 206. is converted into a digital signal by the A/D converter 205 and then read into the CPU 200 (step S ₂ ). If this read paint temperature differs from the previous read value, the paint viscosity at that temperature is referred to from the temperature-viscosity table in the ROM 202 (steps _S3 , _S4 ), and based on that viscosity,
The CPU 200 has a discharge pressure P that provides a predetermined discharge amount Q.
(Step _S5 ). This calculation is performed using the formula P=C ₁ λQ ₂ λ=64Re ⁻¹ (for laminar flow) λ=0.3164Re ^−0.25 (for turbulent flow). Here, λ is the friction coefficient between the fluid and the pipe 6, Re is the Raynozzle number,
C ₁ represents a constant.

Then, the discharge pressure P obtained by the above calculation is
It is converted into a current by the D/A converter 208 and outputted (step S ₆ ), which drives the electro-pneumatic converter 210 via the amplifier 209 and the air-driven regulator 5.
The discharge pressure (FIG. 2) is controlled.

FIG. 5 is a sectional view illustrating the air drive regulator 5 in FIG. 1 in detail. When air enters at a higher pressure than the air inlet 50, the diaphragm 55 is pressed downward, and the needle valve 53 attached to the diaphragm holding members 56, 57 with nuts 58 moves downward. The gap between the paint inlet 51 and the sheet 54 is widened, so that a large amount of paint that enters the paint inlet 51 passes through this and exits from the paint outlet 52. Conversely, when only air at a lower pressure enters the air inlet 50, the gap between the needle valve 53 and the seat 54 becomes narrower, and only a small amount of paint comes out from the paint outlet 52. By using the air-driven regulator 5 having such a structure, the flow rate can be maintained constant under the control of the microcomputer 12 as described above.

FIG. 6 shows another embodiment of the present invention, in which the same symbols as in FIG. 2 indicate the same devices. In addition to detecting the temperature of the paint in FIG. 2, FIG. 6 also detects the fluid pressure on the output side of the air drive regulator 5 with a pressure sensor 16, and inputs that value to the microcomputer 12 via the wiring 17. It also allows pressure feedback control. This enables highly accurate flow rate control.

Effects of the invention According to the invention, the following effects can be obtained. That is, (1) Even if the viscosity of the fluid changes depending on the temperature, a constant flow rate can be ensured.

(2) The device can be simplified and inexpensive.

(3) Even if you change to a fluid with different temperature-viscosity characteristics,
The equipment can easily handle this.

(4) Since there are no rotating parts such as flowmeters, the device does not wear out and can therefore maintain stable performance over a long period of time.

It exhibits excellent effects such as.

[Brief explanation of the drawing]

Figure 1 is a block diagram showing the configuration of the present invention;
The figure is a block circuit diagram showing one embodiment of the present invention applied to a coating device, Figure 3 is a detailed circuit diagram of a microcomputer, temperature sensor, and electro-pneumatic converter, Figure 4 is a flowchart, Figure 5 is the first
6 is a sectional view of the air drive regulator 5 in the figure, and FIG. 6 is a block circuit diagram of a second embodiment of the present invention. 1: paint tank, 3: pump, 5: air driven regulator, 7: paint gun, 8: industrial air source,
10: Electropneumatic converter, 12: Microcomputer, 14: Temperature sensor, 16: Pressure sensor.

Claims (1)

[Scope of utility model registration request] In a flow rate control device for a fluid transfer device that pumps fluid in a tank to a fluid output device,
A temperature sensor that directly detects the fluid temperature and outputs a temperature signal, a memory means that stores temperature-viscosity data of the fluid in advance, and calculates the current fluid viscosity from the data and the temperature signal. A calculation means that outputs a control signal according to the value, a pneumatic control means that controls the discharge pressure of the fluid according to the control signal, and a pressure regulator that continuously transfers the fluid at a constant flow rate according to the controlled discharge pressure. A flow rate control device characterized by being provided with.