JPH0617084U - Flow switch - Google Patents

Abstract

(57) [Abstract] [Purpose] To provide a flow switch with a high response speed. [Structure] Cylinder hole 22 formed in housing 20
A piston 3 which is slidably supported in the cylinder hole 22 by communicating an inlet port 27 and an outlet port 23 with each end of the piston 3
0 is urged by the spring 36, and the tip end surface 32 thereof abuts on the seat surface 26 formed on the inner end surface of the cylinder hole 22 on the inlet port 27 side. The piston 30 uses the spring 3 when there is no fluid flow from the inlet port side to the outlet port side.
The tip surface 32 is brought into contact with the seat surface 26 by 6 to close the communication between both ports, and when there is the flow of the fluid, it moves against the spring 36 to open the communication between both ports. The movement of the piston 30 actuates the proximity switch 40 provided outside the housing 20.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a flow switch for detecting a flow of a fluid, and more particularly to a flow switch having a high response speed suitable for use in controlling a paint pump by air for spraying in a coating apparatus using high viscosity paint.

[0002]

[Prior art]

 In a coating device using high-viscosity paint, the paint cannot be sprayed only by the pressure of the paint pump. Therefore, as shown in FIG. 3, the spray gun 14 has an air compressor in addition to the paint from the paint pump 10. The air for spraying from 13 is supplied. In this type of coating apparatus, the operation of the paint pump 10 is remotely controlled by operating the spray gun 14. Specifically, when the spray gun 14 is stopped, the flow of the spray air is stopped by a flow switch. It is detected by FS, and the electric motor 11 of the paint pump 10 is stopped by the control device 17.

Conventionally, as such a flow switch FS, a diaphragm type switch as shown in FIG. 5 has been used. This separates a chamber 2 formed in the housing 1 into two working chambers 2a and 2b by a diaphragm 3, and one of the first working chambers 2a is provided with an inlet port 4a and an outlet port 4b so as to blow air. A throttle 4c for detecting an air flow is formed between the first working chamber 2a and the outlet port 4b while allowing the air to pass therethrough. A movable plate 6 and a magnet 8 are provided at the center of the diaphragm 3 on the side of the second working chamber 2b, and the reed switch is actuated by the magnet 8 on the housing 1 while being biased by the spring 7 toward the first working chamber 2a. 9 is attached. The downstream side of the throttle 4c is communicated with the second working chamber 2b by the passages 5a and 5b, and when the blowing air is flowing, a pressure drop is generated by the throttle 4c so that the two working chambers 2a and 2b are generated. Due to the pressure difference, the magnet 8 is moved against the spring 7 and the reed switch 9 is closed to detect the flow of the blowing air.

[0004]

[Problems to be solved by the device]

 However, such a conventional flow switch converts a change in the air flow into a pressure change by the throttle 4c and operates the diaphragm 3 by this pressure change, so that the response speed is slow and the spray gun is closed before the paint is closed. There is a delay of about 2 to 3 seconds until the pump stops, and about 1 second until the paint pump starts operating after the spray gun is opened. For this reason, the paint is fed into the pressure-resistant hose 15 from the time when the spray gun 14 is closed until the paint pump 10 is stopped, and the pressure rises and accumulates as compared with that during the spraying work. There is a problem in that the paint that has accumulated at high pressure spouts at the moment when the is opened and a so-called spit phenomenon occurs, causing the pattern on the painted surface to collapse locally.

The present invention aims to increase the response speed of a flow switch in order to solve such a problem.

[0006]

[Means for Solving the Problems]

 To this end, the flow switch according to the present invention, as illustrated in FIGS. 1 to 4, communicates with a housing 20 having a cylinder hole 22 whose both ends are closed, and each end of the cylinder hole 22. The inlet port 27 and the outlet port 23, a seat surface 26 coaxially formed on the inner end surface of the cylinder hole 22 on the inlet port 27 side, and slidably supported in the cylinder hole 22 in the axial direction. The flow of the fluid from the inlet port 27 side to the outlet port 23 side has a tip surface 32 that is elastically urged toward the inlet port 27 side by a spring 36 and can abut against the seat surface 26. If not, the tip end surface 32 is brought into contact with the seat surface 26 by the spring 36 to close the communication between the ports 27 and 23, and when the fluid flows, the spring 36 A piston 30 that moves against the opening to open the communication between the ports 27 and 23, and a proximity switch 40 that is provided outside the housing 20 and detects the movement of the piston 30 depending on the presence or absence of the fluid flow. Be prepared.

[0007]

When there is a fluid flow from the inlet port 27 toward the outlet port 23, the piston 30 moves against the spring 36, and the tip end surface 32 thereof is separated from the seat surface 26, and the piston 30 of both ports 27 and 23 is moved. Although the communication between the ports is open, when the flow of the fluid is eliminated, the piston 30 abuts the tip surface 32 of the piston 30 against the seat surface 26 by the spring 36 to close the communication between the ports 27 and 23. The opening and closing of the communication and the associated movement of the piston 30 are performed in direct response to the fluid flow itself from the inlet port 27 toward the outlet port 23, and the proximity switch 40 detects the movement of the piston 30. Detects the fluid flow.

[0008]

[Effect of device]

 As described above, according to the present invention, the movement of the piston is performed in direct response to the fluid flow itself from the inlet port to the outlet port, so that the delay in response is extremely small and the presence or absence of fluid flow. The detection speed of is significantly faster than the conventional one. Therefore, if the flow switch of the present invention is used to control the paint pump by the air for spraying in the coating equipment using high-viscosity paint, the pressure inside the pressure hose that sends the paint when the spray gun is stopped The climb will be slight and the spit phenomenon will not occur the next time the spray gun is opened.

[0009]

【Example】

 The present invention will be described below with reference to the embodiments shown in the accompanying drawings.

First, the entire coating apparatus using the flow switch of the present invention will be described. Mainly, as shown in FIG. 3, the coating pump was fed from the coating pump 10 to the spray gun 14 through the pressure-resistant hose 15. The high-viscosity paint is sprayed onto the coating surface (not shown) such as the outer wall of the building in a relatively large particle state by the compressed air sent from the air compressor 13 through the air hose 16. The electric motor 11 that drives the paint pump 10 receives signals from the pressure sensor 12 that detects the pressure of the paint passing through the pressure-resistant hose 15 and the flow switch FS that detects the air flow in the air hose 16. It is controlled by the control device 17 which operates as follows. The control device 17 is connected with a thermal switch 11a for detecting the temperature of the electric motor 11 and a pressure regulator (variable resistor for pressure regulation) 17b for regulating the pressure of the paint passing through the pressure-resistant hose 12, and is also detected by the pressure sensor 12. A pressure display device 17a for displaying the discharged paint pressure is connected.

Next, the structure of the flow switch FS, which is the main part of the present invention, will be described with reference to FIGS. 1 and 2. The housing 20 of the flow switch FS is composed of a switch case 21 having a cylinder hole 22 having one end opened, and a case cap 25 attached to the switch case 21 to hermetically close one end of the cylinder hole 22. Made of aluminum. On the side opposite to the case cap 25, the switch case 21 has an outlet port 23 communicating with the inside of the other end of the cylinder hole 22. A concave conical seat surface 26 is coaxially formed on the end surface of the case cap 25 that forms the inner end surface of the cylinder hole 22 in the case cap 25, and the cylinder hole 22 is inserted through the center portion of the seat surface 26. An inlet port 27 communicating with the inside is formed. The housing 20 is fixed to the machine frame 19 (only part of which is shown) of the coating device by four mounting screws 29, and the flow switches FS are attached to the ports 27 and 23 respectively in the middle of the air hose 16. Two unions 28 (only one shown) are screwed in.

The piston 30 slidably supported in the cylinder hole 22 of the housing 20 is made of structural synthetic resin, and is elastically biased toward the case cap 25 by a spring 36. As a result, the conical tip end surface 32 formed on the small diameter portion 31 of the piston 30 on the inlet port 27 side is airtightly contacted with the seat surface 26 via the O-ring 35. A hollow portion is formed on the outlet port 23 side of the piston 30, and two communication holes 33 communicating with the hollow portion are opened in the small diameter portion 31. Therefore, as shown in the figure, the communication between the inlet port 27 and the outlet port 23 is closed when the tip end surface 32 of the piston 30 is in contact with the case cap 25 through the O-ring 35 by the spring 36 as shown in the figure. When the piston 30 retracts against the spring 36 and the O-ring 35 separates from the seat surface 26, the inlet port 27 and the outlet port 23 are communicated with each other through the communication hole 33. In the present embodiment, the seat surface 26 and the tip surface 32 are conical, but they may be planar, and the O-ring 35 is not always necessary.

As shown in FIGS. 1 and 2, a reed switch 41 is attached to the center of the rear surface of the housing 20 through a bracket 45 having an L-shaped cross section and mounting screws 46 and 47. A magnet 42 magnetized in the axial direction is held in an annular groove 34 formed on the outer periphery of 30. The reed switch 41 and the magnet 42 form a proximity switch 40 that operates by the movement of the piston 30. The proximity switch 40 is not limited to the magnetic type as in this embodiment, but may be another type such as a high frequency type or a capacitive type.

As shown in FIG. 4, the relay 170 included in the control device 17 has the coil 170 a connected in series with the reed switch 41 of the proximity switch 40 and connected to the AC power supply 18. The contact point 170b of the relay 170 is connected in series with the electric motor 11 of the paint pump 10 and is connected to the AC power supply 18. Therefore, when the reed switch 41 is opened and closed, the contact point 170b is also opened and closed, and the paint pump 10 is also stopped or operated. A varistor 171 for absorbing surge is connected in parallel to the coil 170a.

When the spray gun 14 is closed and spraying of the paint is stopped, air does not flow to the air hose 16, so that the flow of air from the inlet port 27 to the outlet port 23 of the flow switch FS is reduced. Therefore, the piston 30 is biased by the spring 36 to the forward position where the tip end surface 32 is abutted against the seat surface 26 through the O-ring 35, as shown in the figure, and the piston 30 is moved between the inlet port 27 and the outlet port 23. Communication is closed. However, when the spray gun 14 is opened to start spraying the paint, air flows through the air hose 16 to generate a flow of air from the inlet port 27 toward the outlet port 23, which causes the piston 30 to resist the spring 36. Then, the front end surface 32 is separated from the seat surface 26 to open the communication between the ports 27 and 23. When the spray gun 14 is closed to stop spraying the paint, the spring 36 causes the piston 30 to return to the illustrated position. The magnet 42 provided on the piston 30 has a positional relationship in which the lead switch 41 is not closed in the forward position of the piston 30 and closes the reed switch 41 in the retracted position. Therefore, the reed switch 41 is opened when there is no air flow from the inlet port 27 toward the outlet port 23, and is closed when this air flow occurs.

As described above, since the movement of the piston 30 is directly performed in response to the flow of the fluid itself from the inlet port 27 toward the outlet port 23, the delay of the response to the presence or absence of the air flow is extremely small. Therefore, the detection speed of the fluid by the reed switch 41 is significantly faster than the conventional one. Thus, for example, when the length of each hose 15 and 16 is about 30 meters, the time from closing the spray gun 14 to stopping the electric motor 11 via the relay 170 is 0.5 seconds or less. During this time, the pressure rise in the pressure-resistant hose 15 becomes small, and the next time the spray gun 14 is opened, the spit phenomenon that may locally break the pattern on the painted surface does not occur.

[Brief description of drawings]

FIG. 1 is a longitudinal sectional view of an embodiment of a flow switch according to the present invention.

FIG. 2 is a right side view of the embodiment shown in FIG.

FIG. 3 is an overall configuration diagram of a coating apparatus having a flow switch according to the present invention.

FIG. 4 is a diagram showing a part of a control circuit of the coating apparatus shown in FIG.

FIG. 5 is a cross-sectional view of an example of a conventional flow switch.

[Explanation of symbols]

20 ... Housing, 22 ... Cylinder hole, 23 ... Exit port, 26 ... Seating surface, 27 ... Inlet port, 30 ... Piston,
32 ... Tip surface, 36 ... Spring, 40 ... Proximity switch.

Claims (1)

[Scope of utility model registration request] 1. A housing having a cylinder hole, the ends of which are closed, an inlet port and an outlet port which communicate with each end of the cylinder hole, and a coaxial inner end surface of the cylinder hole on the inlet port side. A seat surface that is formed in an axial direction and a tip surface that is supported in the cylinder hole so as to be slidable in the axial direction and is elastically urged toward the inlet port by a spring and that can abut the seat surface. When there is no fluid flow from the inlet port side to the outlet port side, the tip end surface is brought into contact with the seat surface by the spring to close the communication between the both ports, and when the fluid flow is present, A piston that moves against the spring to open communication between the two ports and a proximity switch that is provided outside the housing and that detects the movement of the piston depending on the presence or absence of the flow of the fluid. A flow switch equipped with a switch.