Paint gun

Abstract

To provide a coating gun that can perform coating stably and efficiently.SOLUTION: A coating gun 1 comprises: a gun main body 10 which has a coating material inflow chamber 17 and a second storage chamber 16 having a communication port 16A communicating with the coating material inflow chamber 17; a nozzle 20 having a valve port 24 and a valve chamber 23; a needle valve 50 that is stored in the valve chamber 23; a trigger shaft 71 that is stored in the second storage chamber 16 and moves the needle valve 50 between a valve-closing position and a valve-opening position; and a diaphragm member 30, arranged to block the communication port 16A, which connects the needle valve 50 to the trigger shaft 71. The diaphragm member 30 comprises: a connection part 31 that connects the needle valve 50 to the trigger shaft 71; a fixed cylindrical part 35 formed into a cylindrical shape, in which one end part of the trigger shaft 71 is stored and which is fixed to an inner peripheral surface of the communication port 16A to closely adhere to the surface; and a diaphragm part 37 formed into a film shape having flexibility, which connects the connection part 31 to the fixed cylindrical part 35.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The technology disclosed herein relates to a paint gun. [Background technology]

[0002] A paint gun equipped with a needle-type on-off valve is known. Such a paint gun has a valve chamber and a valve port, and a needle is disposed inside the valve chamber. The needle is movable between a valve-closed position where it closes the valve port and a valve-opened position where it opens the valve port. A packing is provided inside the paint gun to fit tightly against the outer circumferential surface of the needle and to prevent paint from leaking rearward from the valve chamber. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2002-59034 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above configuration, the packing is in sliding contact with the needle, so there is a risk of paint leaking backward due to sliding wear of the packing, or of pigment particles getting into the gap between the needle and the packing, resulting in poor sliding. To prevent such situations, the packing must be replaced frequently, which is time-consuming. [Means for solving the problem]

[0005] a nozzle having a valve chamber having a valve port through which the paint is discharged to the outside and communicating with the paint inlet chamber; a needle valve disposed in the valve chamber and displaceable between a closed position which blocks the valve port and an open position which opens the valve port; a moving mechanism disposed in the moving mechanism chamber and moving the needle valve between the closed position and the open position; and a diaphragm member disposed to close the communication port and connecting the needle valve and the moving mechanism, the diaphragm member comprising: a connecting portion connecting the needle valve and the moving mechanism; a cylindrical fixed cylinder portion which houses one end of the moving mechanism therein and is fixed in a state of being in close contact with the inner circumferential surface of the communication port; and a flexible membrane-like diaphragm portion which connects the connecting portion and the fixed cylinder portion. Effect of the Invention

[0006] The coating gun disclosed in this specification enables stable and efficient coating. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is a side view showing a partly cutaway view of a paint gun according to an embodiment. [Diagram 2] FIG. 2 is a partially enlarged cross-sectional view showing the surrounding area of ​​a needle valve and a trigger shaft in the spray gun according to the embodiment. [Diagram 3] FIG. 3 is a partially enlarged cross-sectional view of the spray gun according to the embodiment, showing a state in which a needle valve is in a closed position. [Figure 4] FIG. 4 is an exploded cross-sectional view of the needle valve, the diaphragm member, the guide cylinder, and the trigger shaft. [Diagram 5] FIG. 5 is a partially enlarged cross-sectional view showing a rear end portion of a trigger shaft in the spray gun according to the embodiment. [Figure 6] FIG. 6 is a partially enlarged cross-sectional view of the spray gun according to the embodiment, showing a state in which the needle valve is in an open position. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] [Overview of the embodiment] (1) A paint gun disclosed in this specification comprises a gun body having a paint inlet chamber into which paint is supplied and a moving mechanism housing chamber having a communication port communicating with the paint inlet chamber; a nozzle having a valve chamber having a valve port through which the paint is discharged to the outside and communicating with the paint inlet chamber; a needle valve disposed in the valve chamber and displaceable between a closed position which blocks the valve port and an open position which opens the valve port; a moving mechanism disposed in the moving mechanism housing chamber and moving the needle valve between the closed position and the open position; and a diaphragm member disposed to close the communication port and connecting the needle valve and the moving mechanism, the diaphragm member comprising: a connecting portion connecting the needle valve and the moving mechanism; a cylindrical fixed cylinder portion which houses one end of the moving mechanism therein and is fixed in a state of being in close contact with an inner surface of the communication port; and a diaphragm portion which is in the form of a flexible film and connects the connecting portion and the fixed cylinder portion.

[0009] According to the above configuration, the communication port in the moving mechanism housing chamber that communicates with the paint inlet chamber is blocked by the diaphragm member. In addition, since the diaphragm portion is flexible, a certain degree of movement of the connecting portion relative to the fixed cylinder portion is permitted. As a result, the needle valve, the trigger shaft, and the connecting portion move integrally between the open position and the closed position by operating the trigger. With this configuration, unlike the conventional configuration in which a packing is provided on the outer circumferential surface of the needle, there is no paint leakage to the moving mechanism side due to sliding wear of the packing, and no sliding problems due to pigment particles entering the gap between the needle and the packing. This allows stable and efficient painting.

[0010] (2) The diaphragm member may be formed from a single member.

[0011] If the diaphragm member is configured by assembling multiple components, gaps may occur at the connections between the multiple components, and paint may leak through the gaps. However, if the diaphragm member is configured from a single component, there is no risk of paint entering the moving mechanism housing chamber from the paint inlet chamber, and the durability of the paint gun can be improved.

[0012] [Details of the embodiment] Specific examples of the technology disclosed in this specification will be described below with reference to the drawings. Note that the present invention is not limited to these examples, but is defined by the claims, and is intended to include all modifications within the meaning and scope of the claims.

[0013] <Embodiment> An embodiment will be described with reference to Figures 1 to 6. The coating gun 1 of this embodiment is a handgun-type electrostatic coating gun that is held and handled by an operator, and includes a gun body 10 and a nozzle 20 attached to the gun body 10. A needle valve 50, a trigger shaft 71, a coil spring 79, a diaphragm member 30, and a guide tube 40 are housed inside the gun body 10 and the nozzle 20. The needle valve 50, the trigger shaft 71, the diaphragm member 30, and the guide tube 40 are assembled together.

[0014] [Gun body 10] The gun body 10 is made of an insulating resin material. As shown in Fig. 1, the gun body 10 includes a barrel 11 having a nozzle 20 attached to one end thereof, a grip 12 extending obliquely from the other end of the barrel 11 for an operator to hold, a trigger 13 extending from the barrel 11 and disposed near the grip 12, and a paint supply unit 14 disposed near the nozzle 20 on the barrel 11 and connected to a joint 81 connected to a paint hose 80. In the following description, the side of the barrel 11 to which the nozzle 20 is attached (the left side in Fig. 1) is referred to as the front side, and the side to which the grip 12 is disposed (the right side in Fig. 1) is referred to as the rear side.

[0015] The gun barrel 11 has an elongated cylindrical shape as a whole, and as shown in FIG. 2, has a first storage chamber 15, a second storage chamber 16 (an example of a moving mechanism storage chamber), and a paint inlet chamber 17. A high-voltage generator 19 is stored inside the first storage chamber 15. The high-voltage generator 19 has a general configuration including a transformer, a cascade, etc., although not shown in detail. The paint inlet chamber 17 has an opening at the front end of the gun barrel 11. The second storage chamber 16 has a communication port 16A that communicates with the paint inlet chamber 17, and extends from the rear end of the paint inlet chamber 17 to the vicinity of the trigger 13. The internal space of the paint supply unit 14 communicates with the paint inlet chamber 17 via a paint inlet port 17A, and paint supplied from a paint hose 80 is supplied into the paint inlet chamber 17.

[0016] [Nozzle 20] The nozzle 20 is made of synthetic resin and has an overall cylindrical shape as shown in Fig. 3. At the front end of the nozzle 20, there are arranged a throttle section 21 whose diameter decreases toward the front end, and a thin tubular discharge section 22 extending from the front end of the throttle section 21. The internal space of the nozzle 20 communicates with the paint inlet chamber 17 and forms a valve chamber 23 having a valve port 24 at the front end of the discharge section 22. The rear end of the nozzle 20 is accommodated in the paint inlet chamber 17. Paint is supplied into the valve chamber 23 through the paint inlet chamber 17.

[0017] An air cap 25 is attached to the front end of the nozzle 20 that protrudes forward from the barrel 11, and the air cap 25 is fixed to the barrel 11 by a retainer 26. The air cap 25 is generally cylindrical and surrounds the nozzle 20, and has an air outlet (not shown).

[0018] [Diaphragm member 30] 3, the communication port 16A of the second storage chamber 16 is closed by a diaphragm member 30, which prevents paint supplied to the inside of the paint inlet chamber 17 from entering the second storage chamber 16. The diaphragm member 30 is made of synthetic resin, and includes a connecting portion 31 that connects the needle valve 50 and the trigger shaft 71, a cylindrical fixed cylinder portion 35 that is fixed inside the communication port 16A, and a membrane-like diaphragm portion 37 that connects the connecting portion 31 and the fixed cylinder portion 35, as shown in FIGS.

[0019] 4, the connecting portion 31 is generally in the shape of a round bar extending in the front-rear direction, with its front end portion forming a first female threaded portion 32 having a threaded hole opening in its front end surface, and its rear end portion forming a second female threaded portion 33 having a threaded hole opening in its rear end surface. The threaded hole of the first female threaded portion 32 and the threaded hole of the second female threaded portion 33 are partitioned by an intermediate wall 34 and are not communicated with each other.

[0020] 3 and 4, the fixed cylinder portion 35 has a cylindrical shape that is one size larger than the connecting portion 31, and is fixed inside the communication port 16A. The outer peripheral surface of the fixed cylinder portion 35 is in close contact with the inner peripheral surface of the communication port 16A over the entire circumference. A part of the fixed cylinder portion 35 forms a third female screw portion 36 having a screw groove on its inner peripheral surface.

[0021] 3 and 4, the diaphragm portion 37 has a ring-shaped membrane shape, extends like a brim from the outer circumferential surface of the connecting portion 31, and is connected to the edge of the opening on the front end side of the fixed cylinder portion 35. The diaphragm portion 37 is disposed around the entire circumference of the connecting portion 31, and the opening on the front end side of the fixed cylinder portion 35 is blocked by the diaphragm portion 37 and the connecting portion 31. The diaphragm portion 37 is flexible, and allows the connecting portion 31 to move in the front-rear direction relative to the fixed cylinder portion 35.

[0022] It is preferable that the diaphragm member 30 has excellent shape restoring property (restoring force against deformation) and solvent resistance. Suitable materials for the diaphragm member 30 include, for example, ultra-high molecular weight polyethylene and polytetrafluoroethylene (PTFE).

[0023] The diaphragm member 30 is a single, seamless member in which the connecting portion 31, the fixed cylinder portion 35, and the diaphragm portion 37 are integrally connected. Such a member can be formed, for example, by injection molding.

[0024] [Guide tube 40] As shown in Figs. 2 and 4, the guide tube 40 has an elongated cylindrical shape and is accommodated inside the second accommodation chamber 16. As shown in Figs. 3 and 4, the front end of the guide tube 40 has a smaller outer diameter than the other parts and is a third male threaded portion 41 with a thread formed on the outer circumferential surface. As shown in Fig. 3, the third male threaded portion 41 is screwed into the third female threaded portion 36, so that the guide tube 40 is fixed to the fixed tube portion 35. Also, as shown in Figs. 4 and 5, the rear end of the guide tube 40 is a fourth male threaded portion 42 with a thread formed on the outer circumferential surface. A fourth female threaded portion 18 having a thread groove is disposed on the inner circumferential surface of the second accommodation chamber 16, and the fourth male threaded portion 42 is screwed into the fourth female threaded portion 18, so that the guide tube 40 is fixed inside the second accommodation chamber 16. The fixed tube portion 35 is fixed inside the second accommodation chamber 16 via the guide tube 40.

[0025] [Needle valve 50] As shown in Fig. 3, a needle valve 50 is housed inside the paint inlet chamber 17 and the valve chamber 23. As shown in Fig. 4, the needle valve 50 includes a needle shaft 51, a needle cap 54, and a guide member 57.

[0026] The needle shaft 51 is made of, for example, metal, and has an overall round bar shape as shown in Figures 3 and 4. The rear end of the needle shaft 51 is a first male threaded portion 52 having a thread on its outer circumferential surface, and the front end is a fifth male threaded portion 53 having a thread on its outer circumferential surface. The needle shaft 51 is connected to the coupling portion 31 by screwing the first male threaded portion 52 into the first female threaded portion 32.

[0027] The needle cap 54 is made of, for example, synthetic resin, and has a cylindrical shape as a whole, as shown in Figs. 3 and 4. The front end of the needle cap 54 is a tapered seal portion 55 that becomes smaller in diameter as it approaches the tip. Inside the needle cap 54, as shown in Figs. 3 and 4, a resistor 61 and a pin electrode 60 connected to the resistor 61 are housed. The tip of the pin electrode 60 protrudes from the front end of the needle cap 54 to the outside. A high voltage is applied to the pin electrode 60 by the high voltage generator 19. The rear end of the needle cap 54 is a fifth female screw portion 56 having a screw hole that opens on the rear end surface. As shown in Fig. 3, the needle cap 54 is connected to the needle shaft 51 by screwing the fifth male screw portion 53 into the fifth female screw portion 56.

[0028] 3 and 4, the guide member 57 is a member attached to the rear end of the needle cap 54, and has a plurality of protrusions 58 on its outer circumferential surface. These protrusions 58 are slidably engaged with guide grooves (not shown) arranged on the inner wall surface of the valve chamber 23, and the needle valve 50 is guided by the guide grooves to be slidable in the front-rear direction.

[0029] The needle valve 50 is movable between a closed position (position shown in Figure 3) in which the outer peripheral surface of the seal portion 55 abuts the inner peripheral surface of the throttling portion 21 and the valve orifice 24 is blocked, and an open position (position shown in Figure 6) which is a position rearward of the closed position, where there is a gap between the outer peripheral surface of the seal portion 55 and the inner peripheral surface of the throttling portion 21 and the valve orifice 24 is opened.

[0030] [Trigger shaft 71] 2, a trigger shaft 71 and a coil spring 79 are accommodated in the second accommodation chamber 16. The trigger shaft 71 and the coil spring 79 are an example of a moving mechanism that moves the needle valve 50 back and forth between an open position and a closed position in response to the operation of the trigger 13.

[0031] As shown in Figs. 2 and 4, the trigger shaft 71 includes a front shaft 72 and a rear shaft 75. The front shaft 72 is in the shape of an elongated round bar, and most of the front shaft 72 is inserted into the guide tube 40. As shown in Figs. 3 and 4, the front end of the front shaft 72 is a second male screw portion 73 having a screw thread on the outer circumferential surface. The front end of the front shaft 72, including the second male screw portion 73, is housed inside the fixed tube portion 35. The second male screw portion 73 is screwed into the second female screw portion 33, so that the front shaft 72 is connected to the coupling portion 31. As shown in Figs. 4 and 5, the rear end of the front shaft 72 is a sixth female screw portion 74 having a screw hole opening on the rear end surface. As shown in Figs. 4 and 5, the rear shaft 75 includes a round bar-shaped shaft main body 76 that is shorter than the front shaft 72, and a brim-shaped flange portion 77 that protrudes from the outer circumferential surface of the shaft main body 76, and is arranged coaxially with the front shaft 72. The front end of the rear shaft 75 is a sixth male threaded portion 78 having a thread on the outer circumferential surface. The sixth male threaded portion 78 is screwed into the sixth female threaded portion 74, thereby connecting the rear shaft 75 to the front shaft 72. As shown in Fig. 5, a coil spring 79 abuts against the flange portion 77 from the rear, and the trigger 13 abuts against it from the front.

[0032] [Paint gun 1 operation] 2, the needle valve 50 and the trigger shaft 71 are connected via a connecting portion 31. The needle valve 50, the trigger shaft 71, and the connecting portion 31 move integrally in the forward and backward directions when the trigger 13 is operated.

[0033] When the trigger 13 is not operated, the trigger shaft 71 is biased forward by the coil spring 79. As a result, the needle valve 50 is also biased forward and is in the closed position where the valve port 24 is closed (see FIG. 3).

[0034] When the spray gun 1 is used, the operator pulls the trigger 13 toward the grip 12. The trigger 13 pushes the flange portion 77 rearward, and the trigger shaft 71 moves rearward against the bias of the coil spring 79. As described above, the diaphragm portion 37 is flexible and allows the connecting portion 31 to move forward and backward relative to the fixed cylinder portion 35. As the trigger shaft 71 moves rearward, the connecting portion 31 also moves rearward. Accordingly, the needle valve 50 also moves rearward from the closed position to the open position (see FIG. 6). When the needle valve 50 moves to the open position, the valve port 24 is opened, and paint supplied to the inside of the valve chamber 23 is discharged from the valve port 24.

[0035] In addition, in conjunction with the operation of pulling the trigger 13 towards the grip 12, a high voltage is applied to the pin electrode 60 by the high voltage generator 19. This induces an electric charge in the paint that is discharged from the valve port 24 and running along the pin electrode 60, causing the paint particles to fly out in front of the nozzle 20 in an electrically charged state.

[0036] The paint particles projecting forward of the nozzle 20 are sprayed in a spray pattern suitable for painting by the pattern air ejected from the air ejection holes of the air cap 25.

[0037] When the trigger 13 is released, the needle valve 50, the trigger shaft 71, and the connecting portion 31 move forward together due to the elastic restoring force of the coil spring 79. This moves the needle valve 50 to the closed position, and the discharge of paint is stopped.

[0038] [Effects] As described above, according to this embodiment, the paint gun 1 comprises the gun body 10 having the paint inlet chamber 17 into which paint is supplied and the second chamber 16 having the communication port 16A communicating with the paint inlet chamber 17, the nozzle 20 having the valve chamber 23 having the valve port 24 through which paint is discharged to the outside and communicating with the paint inlet chamber 17, the needle valve 50 housed in the valve chamber 23 and displaceable between a valve closed position that closes the valve port 24 and a valve open position that opens the valve port 24, and the nozzle 20 housed in the second chamber 16 and operable to move the needle valve 50 between the valve closed position and the valve open position. the trigger shaft 71 and a coil spring 79, and a diaphragm member 30 arranged to close the communication port 16A and connecting the needle valve 50 and the trigger shaft 71. The diaphragm member 30 comprises a connecting portion 31 connecting the needle valve 50 and the trigger shaft 71, a cylindrical fixed cylinder portion 35 that accommodates one end of the trigger shaft 71 therein and is fixed in a state of being in close contact with the inner surface of the communication port 16A, and a flexible membrane-like diaphragm portion 37 connecting the connecting portion 31 and the fixed cylinder portion 35.

[0039] According to the above-mentioned configuration, the communication port 16A in the second chamber 16 that communicates with the paint inlet chamber 17 is blocked by the diaphragm member 30. In addition, since the diaphragm portion 37 is flexible, a certain degree of displacement of the connecting portion 31 relative to the fixed cylinder portion 35 is permitted. As a result, the needle valve 50, the trigger shaft 71, and the connecting portion 31 move integrally between the open position and the closed position by the operation of the trigger 13. According to this configuration, unlike the conventional configuration in which a packing is provided on the outer circumferential surface of the needle, there is no paint leakage to the moving mechanism side due to sliding wear of the packing, and no sliding failure due to pigment particles entering the gap between the needle and the packing. As a result, stable and efficient painting can be performed.

[0040] Moreover, the diaphragm member 30 is formed from a single member.

[0041] If the diaphragm member is configured by assembling multiple components, gaps may occur at the connections between the multiple components, and paint may leak through the gaps. However, in this embodiment, the diaphragm member 30 is configured from a single component, so there is no risk of paint leaking from the paint inlet chamber 17 to the second housing chamber 16, and the durability of the paint spray gun 1 can be improved.

[0042] <Other embodiments> (1) In the above embodiment, an example was shown in which the technology disclosed in this specification was applied to an air spray gun, but the technology disclosed in this specification can also be applied to an airless gun that paints without supplying air.

[0043] (2) In the above embodiment, the fixed tube portion 35 of the diaphragm member 30 was fixed inside the second housing 16 via a guide tube 40 that was separate from the diaphragm member 30, but the guide tube may be integrated with the diaphragm member. [Explanation of symbols]

[0044] 1: Paint gun 10: Gun body 11: Gun barrel 12: Grip 13: Trigger 14:Paint supply section 15: First Containment Cell 16: Second Containment Cell 16A: Communication port 17:Paint inflow chamber 17A: Paint inlet 18: 4th female thread 19: High voltage generator 20: Nozzle 21: Squeezing section 22:Discharge part 23: Valve chamber 24: Valve mouth 25: Air Cap 26: Retainer 30: Diaphragm member 31:Connection part 32: First female thread 33: Second female thread 34: Intermediate wall 35: Fixed cylinder part 36: Third female thread 37: Diaphragm section 40: Guide tube 41: Third male thread 42: 4th male thread 50: Needle valve 51: Needle shaft 52: First male thread 53: 5th male thread 54: Needle cap 55: Seal part 56: 5th female thread 57: Guide member 58: Convex 60: Pin electrode 61:Resistor 71: Trigger shaft 72: Front shaft 73: Second male thread 74: 6th female thread 75: Rear shaft 76: Shaft body 77: Flange part 78: 6th male thread 79: Coil spring 80: Paint hose 81: Joint

Claims

1. a gun body having a paint inlet chamber into which paint is supplied and a movement mechanism accommodating chamber having a communication port communicating with the paint inlet chamber; a nozzle having a valve chamber communicating with the paint inlet chamber and having a valve port through which the paint is discharged to the outside; a needle valve disposed in the valve chamber and displaceable between a valve closing position at which the valve port is closed and a valve opening position at which the valve port is opened; a movement mechanism disposed in the movement mechanism housing chamber and configured to move the needle valve between the valve closed position and the valve open position; a diaphragm member disposed to close the communication port and connecting the needle valve and the movement mechanism, The diaphragm member is a connecting portion that connects the needle valve and the moving mechanism; a fixed cylinder portion that houses one end of the movement mechanism therein and is fixed in close contact with an inner circumferential surface of the communication port; A paint gun comprising a diaphragm portion having a flexible film shape and connecting the connecting portion and the fixed cylinder portion.

2. 2. The paint gun of claim 1, wherein the diaphragm member is constructed from a single member.

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