JPS6259989B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a diaphragm pump for airless painting using a tappet type check valve.

A diaphragm separates the hydraulic oil chamber and the pump chamber, and by supplying and discharging hydraulic oil to the hydraulic oil chamber, the diaphragm is driven back and forth to increase or decrease the volume of the pump chamber, and the liquid paint sucked from the paint tank is In a diaphragm pump for airless painting that pumps pressure to a spray gun, the valve opens and discharges liquid paint when the volume of the pump chamber decreases and pressurizes the liquid paint, and conversely closes when the pressure decreases. A check valve to prevent backflow is installed in the discharge path that communicates with the spray gun, but in conventional airless painting diaphragm pumps, a valve body made of a steel ball is attached to the valve seat provided in the discharge path by a spring. A pressed ball type check valve is used, and this type of check valve requires a high roundness of the valve body, making it expensive, difficult to form into a unit, and requiring time to assemble. The drawback was that the discharge pressure pulsated significantly due to poor responsiveness.

SUMMARY OF THE INVENTION An object of the present invention is to provide a diaphragm pump for airless painting that eliminates these drawbacks, can be easily assembled into a unit, and has small discharge pressure pulsations.

Hereinafter, one embodiment of the present invention will be described based on the accompanying drawings.

In the recess 2 formed on the upper surface of the lower body 1,
A seat plate 3 with a central hole 4 and a communication hole 5 transparent therein is fitted, and a concave surface 7 corresponding to the recess 2 is formed on the lower surface of the upper body 6, and a concave surface 7 corresponding to the recess 2 is formed between the lower body 1 and the upper body 6. A diaphragm 8 is stretched over the diaphragm 8, with a pump chamber 9 on its upper surface and a hydraulic oil chamber 1 on its lower surface.
A spring 14 is attached to the lower surface of the seat plate 3 to urge the diaphragm 8 downward. A cylinder 12 is fitted into a device hole 11 formed concentrically on the lower surface of the recess 2 of the lower body 1, and the hydraulic oil in the cylinder 12 is moved up and down by the vertical movement of the piston 13 that is tightly fitted into the cylinder 12. The hydraulic fluid is pumped into the hydraulic fluid chamber 10 and sucked back, causing the diaphragm 8 to move up and down as shown by chain lines and solid lines in the figure, and the volume of the pump chamber 9 to be alternately increased and decreased accordingly. .

A device hole 14 is formed in the side surface of the upper body 6 and communicates with the pump chamber 9 through a discharge hole 15, and a check valve 16 is installed in this device hole 14. The check valve 16 has a cylindrical valve body 17.
A valve seat 18 having a conical seat surface 18a is fixed to the inlet side of the valve seat 18, and a holder 19 is screwed onto the valve seat 18 from the outlet side. A valve stem 22 of a valve body 20 having a valve head 21 integrally protruding from a valve stem 22
is slidably fitted into the center hole 23 of the holder 19, and the valve head 21 is biased in the direction of contacting the valve seat 18 and closing the valve by the elasticity of a spring 24 installed between the valve head 21 and the holder 19. , the holder 19 has an outlet 2
5 and a communication hole 2 that communicates the valve body 17 with the outlet 25.
6 is formed, and a spray gun is attached to the other end of a pressure-resistant hose (not shown) connected to the outlet 25, and a suction pipe 28 is connected to the pump chamber 9 via a foot valve 27.
It is connected to a paint tank (not shown).

When the pressure inside the pump chamber 9 increases, the valve body 20 moves back against the elasticity of the spring 24 and the valve head 21 separates from the valve seat 18, thereby opening the valve. The liquid paint that has flowed in from the discharge hole 15 enters the valve body 17, passes through the flow hole 26, and is sent under pressure from the outlet 25 to the spray gun, and when the pressure inside the pump chamber 9 decreases, as shown by the solid line in the figure. The valve head 21 contacts the valve seat 18 to close the valve, thereby preventing the liquid paint from flowing back from the spray gun side into the pump chamber 9. In this embodiment, the valve head 21 is connected to the valve stem. Since a tappet type check valve with a protrusion is used, the valve body 20
The valve opens sufficiently wide due to the slight retraction of the check valve, and therefore, the valve closes quickly, resulting in small discharge pressure pulsations.Also, all parts of the check valve are housed within the valve body, making it a unit. Since the valve head 21 has a conical shape, the seat surface 21a of the valve head 21 has the advantage of being easy to perform precise machining.

As specifically explained in the above embodiment,
The airless painting diaphragm pump of the present invention is
A hydraulic oil chamber and a pump chamber are separated by a diaphragm, and a foot valve is interposed in a suction passage that communicates the pump chamber with a paint tank, and a check valve is interposed in a discharge passage that communicates with a spray gun. The diaphragm is reciprocated by supplying and discharging hydraulic oil to increase and decrease the volume of the pump chamber, and the foot valve and check valve are alternately opened and closed to discharge the liquid paint sucked in from the suction path from the discharge path. In the airless painting diaphragm pump, the check valve has a valve seat attached to the inlet side of the cylindrical valve body and a holder attached to the outlet side, and a conical seat surface that approaches and separates from the valve seat. A valve body is provided with a valve stem protruding from the valve head that is slidably fitted into a guide hole of the holder, and a spring is installed between the valve body and the holder to prevent the valve head from moving. The main feature is that the valve seat is biased in the direction of contact with the valve seat, and the pulsation of the discharge pressure is small, the paint can be stably supplied, and it is easy and inexpensive to manufacture. It produces the effects that can be provided.

[Brief explanation of the drawing]

The accompanying drawings are cross-sectional views of one embodiment of the invention. 8: Diaphragm, 9: Pump chamber, 10: Hydraulic oil chamber, 16: Check valve, 17: Valve body, 1
8: Valve seat, 19: Holder, 20: Valve body, 21: Valve head, 21a: Seat surface, 22: Valve stem, 24: Spring, 27: Foot valve.

Claims (1)

[Claims] 1. A hydraulic oil chamber and a pump chamber are separated by a diaphragm, a foot valve is interposed in a suction path that communicates the pump chamber with a paint tank, and a check valve is interposed in a discharge path that communicates with a spray gun. The diaphragm is reciprocated by supplying and discharging hydraulic oil to increase and decrease the volume of the pump chamber,
In the diaphragm pump for airless painting, the foot valve and the check valve are alternately opened and closed to discharge the liquid paint sucked in from the suction passage from the discharge passage, and the check valve is disposed on the inlet side of the cylindrical valve body. A valve seat is attached to the valve seat, a holder is attached to the outlet side, and a valve stem is protruded from the valve head having a conical seat surface that approaches and separates from the valve seat, and which fits freely into the guide hole of the holder. A diaphragm for airless painting, comprising a valve body and a spring installed between the valve body and the holder to urge the valve head in a direction to bring it into contact with the valve seat. pump.