JPH0513425Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] This invention relates to an automatic flow rate adjustment device for a flow gun that automatically adjusts the flow rate of a liquid, particularly a high viscosity liquid.

[Prior Art] As a manual flow gun for applying high viscosity liquids such as sealants and adhesives, the one shown in FIG. 4 is conventionally known.

To explain this simply, pressurized high viscosity liquid is supplied from the joint 5 side to the fluid supply side channel 6 formed in the flow gun main body G via a conduit (not shown).

When the trigger 4 is operated in this state, the on-off valve 1 separates from the valve seat 2 against the spring 3 and becomes open, allowing the high-pressure liquid in the fluid supply channel 6 to pass through the valve gap. The fluid flows into the fluid discharge side channel 7 and is applied from the discharge nozzle 8 to the member to be coated.

[Problem that the invention attempts to solve]

However, in such a conventional flow gun, when the on-off valve 1 is opened by operating the trigger 4 in the illustrated state where it is seated on the valve seat 2 due to the biasing force of the spring 3, water is supplied to the flow path 6. A large amount of high-pressure, high-viscosity liquid is discharged from the discharge nozzle 8 through the on-off valve 1 provided at the connection between the fluid supply channel 6 and the fluid discharge channel 7.

As a result, a pressure loss occurs that is proportional to the discharge flow rate, and the pressure of the pressurized liquid acting on the valve portion decreases rapidly, causing a large change in the flow rate of the liquid.

In other words, when attempting to apply a high viscosity liquid in the form of a bead of the required thickness by operating the trigger 4 at a constant speed, the applied portion expands into a ball shape immediately after discharge begins and then converges to a constant thickness, so that after application, the excess expanded portion of the initial discharge portion must be removed by hand, etc.

In addition, in order to avoid this phenomenon, an operation method has been attempted in which the operating speed of the trigger 4 is adjusted depending on the flow rate to always obtain a constant flow rate, but this requires skill on the part of the operator. Also, even with this method, it is extremely difficult to obtain a constant flow rate throughout.

This invention was made in view of such conventional problems, and an object thereof is to provide an automatic flow rate adjustment device for a flow gun that can adjust the discharge amount.

[Means for solving problems]

In order to achieve this object, the present invention forms a fluid supply side flow path and a fluid discharge side flow path in the flow gun main body, and a flow path is formed at a connecting portion between the fluid supply side flow path and the fluid discharge side flow path. In an automatic flow rate adjustment device for a flow gun, the flow gun body is provided with an on-off valve that opens and closes, and a discharge nozzle that communicates with the fluid discharge side flow path is provided in the flow gun body, wherein a piston in which a communication hole is formed is inserted into the fluid discharge side flow path. The piston is provided with a tapered part that is slidably mounted in the axial direction and changes the opening area of the throat part provided in the fluid discharge side flow path as the piston slides in the axial direction, This automatic flow rate adjustment device for a flow gun is characterized in that the piston is provided with a spring member that applies an elastic force in a direction that increases the opening area of the throat portion.

[Function] With the above configuration, when the pressure of the fluid supplied to the discharge nozzle is high and the flow rate exceeds the set value, the piston provided on the upstream side of the discharge nozzle closes the fluid discharge side flow path. The opening area of the throat portion is narrowed, flow path resistance increases, and the flow rate decreases.
Conversely, when the pressure of the fluid becomes low and the flow rate becomes less than the set value, the spring member increases the opening area of the throat part and increases the flow rate.
The flow rate never exceeds the set value, and the flow rate is automatically adjusted.

[Embodiment] Hereinafter, an embodiment of this invention will be described with reference to FIGS. 1 to 3 of the accompanying drawings, and parts corresponding to FIG. 4 are designated by the same reference numerals.

FIG. 1 is a diagram showing the main parts of an automatic flow rate adjustment device for a flow gun according to an embodiment of the invention, and FIG.
The figure shows the overall structure. As shown in FIG. 3, this flow rate automatic adjustment device has a fluid supply side flow path 6 and a fluid discharge side flow path 7 in this flow gun main body G.
High viscosity liquid is supplied to the fluid supply side channel 6 from the joint 5 side, and an on-off valve 1 is provided at the connecting portion between both channels 6 and 7 as shown in the figure. It is provided.

This on-off valve 1 causes fluid from a fluid supply side flow path 6 to flow into a fluid discharge side flow path 7 by operating a trigger 4 against the elastic force of a spring 3. As shown in FIG. 1, an adapter 14 is attached to the tip of the flow gun body G.
An outer cylinder 11 is screwed to the tip of the cylinder 11 and sealed with an O-ring 12. Inside this outer cylinder 11 is a discharge nozzle 15 sealed by an O-ring 13.
are screwed together. The discharge port 15a at the tip of the discharge nozzle 15 is connected to the discharge nozzle 15 and the adapter 1.
It communicates with a fluid discharge channel 7 formed in 4. At the rear end of the discharge nozzle 15 is a cylinder 15b.
A slit 15c is formed along the axial direction in this cylinder 15b.

A throat portion 20 is formed at the rear end of the discharge nozzle 15 so as to be located within the fluid discharge side flow path 7, and a free piston 16 having a tapered portion 16c that changes the opening area of the throat portion 20 is axially moved. It is slidably attached. A plurality of communication holes 16a are formed in the free piston 16 to communicate the upstream side and the downstream side of the fluid discharge side flow path 7.

A spring member 17 is attached within the outer cylinder 11 to apply a resilient force in a direction that increases the opening area of the throat portion 20 with respect to the piston 16, that is, in the right direction (upstream direction) in the figure.

The free piston 16 has a tapered portion 16c at its tip and is integrated with a plunger portion 16b that loosely fits into the cylinder portion 15b of the nozzle 15. This plunger portion 16b and the discharge nozzle 15
A pressure compensation type flow control valve 18 is constituted by the cylinder portion 15b, the spring member 17, and the like.

Next, the operation of the embodiment thus constructed will be described, but first, with reference to FIG. 2, the operating principle of this invention will be explained with reference to a conventional poppet type flow control valve.

When pressurized liquid is supplied from the direction of arrow A,
A part of it flows from the upstream side to the downstream side through the communication hole 16a of the free piston 16, causing a pressure loss proportional to the flow rate. This pressure loss causes
The free piston 16 is pushed downstream against the spring 17, and the free piston 16 reaches a position where the pushing force is balanced with the biasing force of the spring 17 toward the upstream side.
Move 6.

When the position of the free piston 16 changes, the resistance of the throat portion 20 of the fluid discharge side channel 7 changes,
When the flow rate increases, the valve gap narrows and the flow path resistance increases, reducing the flow rate. When the flow rate decreases, the valve gap widens, the flow path resistance decreases, and the flow rate increases, keeping the flow rate at a constant value. .

In the embodiment shown in FIG. 1, the flow rate control valve 18 is replaced with the poppet type flow control valve shown in FIG. The flow rate is adjusted by opening and closing a slit 15c provided in the cylinder portion as a valve, thereby making it possible to precisely adjust the flow rate in proportion to the amount of movement of the free piston 16.

Figure 3 shows an application example of this invention in which such an automatic liquid flow rate adjustment mechanism is incorporated into a manual flow gun to automatically adjust the flow rate. Even if large pressure fluctuations occur, the flow path resistance can be automatically adjusted to keep the discharge flow rate to a constant level.

This idea can also be applied to flow guns that apply relatively low viscosity liquids such as paints that are not highly viscous such as sealants and adhesives.
Moreover, it can be used not only for manual flow guns but also for automatic flow guns.

Furthermore, in the above embodiment, the pressure compensation type flow control valve 18 is a needle valve having a slit 15c in the cylinder portion 15b, but if particularly precise flow rate adjustment is not required, a poppet shown in FIG. It can also be replaced with a valve.

[Effect of idea]

As described above, the automatic flow rate adjustment device for a flow gun according to this invention has a piston in which a communication hole is formed so as to be slidable in the axial direction within the fluid discharge side flow path. The piston is provided with a tapered portion that changes the opening area of the throat portion as the piston slides in the axial direction, and a spring member is provided on the piston that biases the piston with an elastic force in the direction of increasing the opening area of the throat portion. This makes it possible to increase the flow path resistance and reduce the flow rate when the liquid pressure is high at the beginning of discharge, without relying on the skill level of the operator or on a special valve opening/closing mechanism with a complicated structure.
It is possible to obtain the same stable discharge flow rate as in the steady state after the pressure has decreased.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing an embodiment of this invention, Fig. 2 is an explanatory diagram showing the principle of operation, Fig. 3 is a sectional view showing an example of application of this invention to a flow gun, and Fig. 4 is a sectional view showing an example of application of this invention to a flow gun. FIG. 2 is a cross-sectional view illustrating a conventional flow gun. 1... Needle valve, 2... Valve seat,
15...Discharge nozzle, 16...Free piston,
15b...Cylinder part of the discharge nozzle, 16b...
Plunger part of free piston, 17... spring,
18...Pressure compensation type flow control valve.

Claims (1)

[Claims for Utility Model Registration] A fluid supply side flow path and a fluid discharge side flow path are formed in the flow gun main body, and an opening/closing method for opening and closing the flow path at a connecting portion between the fluid supply side flow path and the fluid discharge side flow path. In an automatic flow rate adjustment device for a flow gun, the flow gun body is provided with a valve and a discharge nozzle that communicates with the fluid discharge side flow path, wherein a piston in which a communication hole is formed is axially inserted into the fluid discharge side flow path. The piston is provided with a tapered part that is slidably attached and that changes the opening area of a throat part provided in the fluid discharge side flow path as the piston slides in the axial direction, An automatic flow rate adjustment device for a flow gun, characterized in that it is provided with a spring member that applies a resilient force in the direction of increasing the opening area of the throat portion.