JPH04219475A - Metering pump - Google Patents

Abstract

PURPOSE:To make a metering pump accurately pressure-feed a constant quantity of liquid. CONSTITUTION:A metering pump 1 is composed of a pump body 5 which is provided with an inflow port 5b below a flow path 5a extending vertically and an outflow port 5c at the top of the flow path 5a, and a piston 6 which is slidably inserted into the flow path 5a and has a through-hole 6a. The piston 6 is moved vertically by compressed air supplied to a cylinder part 6f provided on its outer peripheral side. Liquid flowing in through the inflow port 5b is passed through the through-hole 6a and fed to the outflow port 5c at the top of the flow path 5a by the reciprocatory motion of the piston 6.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a metering pump, and more particularly to a metering pump configured to accurately pump a fixed amount of liquid.

0002

2. Description of the Related Art Conventional metering pumps include, for example, a first piston-cylinder mechanism on the driving side and a second piston-cylinder mechanism on the driven side. When the first piston is driven by supplying a working fluid such as, the second piston of the second piston cylinder mechanism connected to the first piston is configured to reciprocate within the second cylinder chamber. There are metering pumps available. This type of metering pump has an inflow side check valve that allows fluid to pass through the inflow port of the second cylinder chamber, and an outflow side check valve that allows the fluid to pass through the outflow port of the second cylinder chamber. A valve is provided. The inlet is provided at the bottom of the second cylinder chamber, the outlet is provided at the side of the second cylinder chamber, and a flow path from the inlet to the inlet is formed in a complicated manner. .

0003

However, in the above-mentioned conventional metering pump, the flow path from the inlet to the outlet of the second cylinder chamber is complicated. When air bubbles are mixed into the liquid, the air bubbles tend to accumulate in the flow path, making it difficult to discharge the air bubbles to the outside.

As mentioned above, even when the second piston reciprocates within the second cylinder, only a small amount of liquid flows in because air bubbles are accumulated in the flow path from the inlet to the outlet. Since the bubbles are compressed during discharge and the amount of bubbles is constantly changing, there is a problem that a fixed amount of liquid cannot be accurately pumped.

Furthermore, in the metering pump described above, the first piston-cylinder mechanism on the driving side and the second piston-cylinder mechanism on the driven side are connected in series, so the setting space is large and the entire device becomes large. was.

[0006] Accordingly, an object of the present invention is to provide a metering pump that solves the above problems.

[0007]

[Means for Solving the Problems] The present invention has a linear channel extending vertically inside the channel, an inlet is provided at the lower end of the channel, and an outlet is provided at the upper end of the channel. a pump body provided with a pump body; a piston that is slidably inserted into a flow path of the pump body and has a through hole therein that communicates the inlet and the outlet; and a piston that connects the inlet to the inside of the flow path The pump includes an inflow side check valve that opens and closes the piston, an outflow side check valve that opens and closes the through hole from the outflow side of the piston, and a drive unit that is provided on the outside of the pump body and reciprocates the piston.

[0008]

[Operation] The piston is configured to be driven by the drive section on the outer circumferential side and slide within the flow path of the pump body, and the inlet at the lower end of the flow path and the upper end of the flow path are connected through a through hole penetrating the inside of the piston. The fluid flowing in from the inlet is forced to the outlet side.

[0009]

DESCRIPTION OF THE PREFERRED EMBODIMENTS FIG. 1 shows a liquid supply system to which an embodiment of a metering pump according to the present invention is applied.

In the figure, a metering pump 1 is disposed between liquid feeding pipes 3 and 4 that feed liquid stored in a storage tank 2.

The metering pump 1 generally consists of a pump body 5, a piston 6 built into the pump body 5, an inflow side check valve 7, and an outflow side check valve 8. Further, the piston 6 is provided with a large diameter portion 6B on the outer peripheral side of the small diameter portion 6A. This large diameter portion 6B functions as a driving portion for driving the piston 6, and is provided on the outside of the pump body 5.

The pump body 5 has an assembled structure in which a lower part 5A, an upper part 5B, and a lid 5C are combined to facilitate assembly of the piston 6. Further, the pump main body 5 is a cylindrical body having a flow passage 5a therein, and is installed in such a direction that the flow passage 5a extends upwardly and downwardly.

An inlet 5b to which the liquid feeding pipe 3 is connected is provided at the lower end of the channel 5a, and an outlet 5c to which the liquid feeding pipe 4 is connected is provided at the upper end of the channel 5b.

[0014] Also, a small diameter portion 6 of the piston 6 is disposed within the flow path 5a.
A is slidably fitted into the lower end of the small diameter portion 6a and the inlet 5b.
A suction chamber 5d is formed between the small diameter portion 6a and the outlet 5b, and a discharge chamber 5e is formed between the upper end of the small diameter portion 6a and the outlet 5b.

The pump main body 5 has a cylinder portion 5f having a larger diameter than the flow path 5a in the middle portion.
The large diameter portion 5B of the piston 6 is slidably fitted inside. Therefore, as shown in FIG. 2(A), the cylinder portion 5
f is defined by the large diameter portion 5B into an upper chamber 5f1 and a lower chamber 5f2.

The piston 6 has a through hole 6a that penetrates in the axial direction at the center of the small diameter portion 6A, and the above-mentioned suction chamber 5d and discharge chamber 5 are connected to each other.
e is communicated with through hole 6a. A recess 6b into which a through hole 6a opens is formed in the upper part of the small diameter portion 6A. Furthermore, the spaces between the piston 6, the flow path 5a, and the cylinder portion 5f are sealed by O-rings 6c to 6e.

Reference numeral 9 denotes a ball valve body of the outflow side check valve 7, which is inserted into the recessed portion 6 to open and close the upper opening 6a1 of the through hole 6a.
It is incorporated within b. Reference numeral 10 denotes a ball valve body of the inflow side check valve 8, which is installed in the suction chamber 5d so as to open and close the inflow port 5b from the flow path 5a side.

Reference numeral 11 denotes a four-way solenoid valve, which has an air inlet 11a connected to an air source (composed of a compressor, etc.) 12, and a first air outlet connected to the upper chamber 5f1 of the cylinder portion 5f via an air pipe 13. 11b, a second air outlet 11c connected to the lower chamber 5f2 of the cylinder portion 5f via the air pipe 14, and an exhaust port 11d.

The four-way solenoid valve 11 is configured to switch in response to a signal from the control section 15, and an air source 12 is connected to either the upper chamber 5f1 or the lower chamber 5f2 of the cylinder section 5f.
The switching operation is performed so as to supply compressed air from the upper chamber 5f1 or the lower chamber 5f2 and exhaust air from the other chamber.

As described above, in the metering pump 1, the piston 6 is driven toward the outer periphery of the small diameter portion 6A of the piston 6, which pumps liquid from the liquid storage tank 2, so that the driving portion is located outside the pump body 5. Since the large diameter portion 6B is provided and the drive side and driven side are integrated, the structure is much more compact than the conventional one. Therefore, the installation space of the metering pump 1 is small, and the installation location is not limited.

Furthermore, since the large diameter portion 6B can have a larger pressure receiving area than the small diameter portion 6A, sufficient driving force can be obtained despite the compact size.

[0022] Here, the operation of the metering pump 1 having the above structure will be explained. In FIG. 1, the piston 6 is moving downward in the X direction. In this state, the four-way solenoid valve 11
5, the air inlet 11a and the air outlet 11c communicate with each other, and the air inlet 11b and the exhaust outlet 11d communicate with each other.

Therefore, compressed air from the air source 12 is supplied to the lower chamber 5f2 of the cylinder 5f via the air pipe 14. At the same time, the upper chamber 5f1 of the cylinder chamber 5f communicates with the exhaust port 11d of the four-way solenoid valve 11 via the air pipe 13. Therefore, the large diameter portion 6B of the piston 6 is located in the lower chamber 5f2.
It is pressed in the Y direction by the air pressure supplied to the
A) Move upward as shown in the direction.

[0024] As a result, the ball valve body 1 in the suction chamber 5d
0 moves away from the inlet 5b, and the inflow side check valve 7 opens. Therefore, as the piston 6 moves upward in the Y direction, the liquid stored in the liquid storage tank 2 is sucked into the suction chamber 5d via the liquid feeding pipe 3.

At the same time, the liquid in the discharge chamber 5e flows through the outlet 5c.
The liquid is fed under pressure to downstream equipment (not shown) via a liquid feeding pipe 4 connected to the liquid feeding pipe 4 .

As shown in FIG. 2(B), when the piston 6 moves upward to the sliding limit position in the Y direction, the large diameter portion 6B comes into contact with the upper inner wall of the cylinder portion 5f and stops. Furthermore, piston 6
When the valve moves upward, the ball valve body 9 of the outflow side check valve 8 closes the through hole 6a, and the liquid in the discharge chamber 5e flows into the suction chamber 5.
Prevent backflow to d.

Next, when a switching signal is output from the control section 15, the four-way solenoid valve 11 communicates between the air inlet 11a and the air outlet 11b, and the air inlet 11c and the air outlet 11d.
Switches so that they communicate with each other.

Therefore, compressed air from the air source 12 is supplied to the upper chamber 5f1 of the cylinder portion 5f via the air pipe 13. Further, the lower chamber 5f2 of the cylinder chamber 5f communicates with the exhaust port 11d of the four-way solenoid valve 11 via the air pipe 14.

Therefore, the large diameter portion 6B of the piston 6 is located in the upper chamber 5.
It is pressed in the X direction by the air pressure supplied to f1,
It moves downward as shown in FIG. 2(C).

As a result, the ball valve body 9 in the recess 6b of the piston 6 is pressed by the liquid in the suction chamber 5d pressurized by the downward movement of the piston 6, and the upper opening 6 of the through hole 6a is pressed by the liquid in the suction chamber 5d.
a1, and the outflow side check valve 8 closes. Therefore, the liquid sucked into the suction chamber 5d as described above flows into the discharge chamber 5e through the through hole 6a as the piston 6 moves downward.

As shown in FIG. 1, when the piston 6 moves down to the sliding limit position in the X direction, the large diameter portion 6B touches the cylinder portion 5f.
It stops when it comes into contact with the lower inner wall. Incidentally, when the piston 6 moves downward, the ball valve body 10 of the inflow side check valve 7 closes to the suction chamber 5.
The inlet 5b is closed by the pressure and weight of the liquid in the suction chamber 5d, thereby preventing the liquid in the suction chamber 5d from flowing back.

Furthermore, due to the downward movement of the piston 6, the discharge chamber 5e
Although the side ball valve body 9 is displaced in the opening direction, the pressurized liquid is supplied from the through hole 6a to the discharge chamber 5e, so the liquid in the liquid supply pipe 4 does not flow back.

As described above, as the piston 6 reciprocates in the flow path 5a, the liquid in the liquid storage tank 2 is fed to the downstream side in fixed amounts.

[0034] Now, let us consider the case where air bubbles are mixed into the liquid. As described above, when the piston 6 moves upward in the Y direction and the liquid from the liquid supply pipe 3 is sucked into the suction chamber 5d, if air bubbles are mixed in the liquid, the air bubbles will move to the upper part of the suction chamber 5d. Moving.

Since the upper part of the suction chamber 5d filled with liquid communicates with the lower opening 6a2 of the through hole 6a of the piston 6, the air bubbles accumulated in the upper part of the suction chamber 5d gradually flow into the through hole 6.
They gather near the lower opening 6a2 of a.

Next, when the piston 6 moves downward as shown in FIG. 2(C), the liquid filled in the suction chamber 5d is pressurized and forced out into the through hole 6a. Therefore, the air bubbles accumulated in the upper part of the suction chamber 5d flow into the through hole 6a along with the flow of liquid, and are forced into the discharge port chamber 5e.

Furthermore, the bubbles contained in the liquid filled in the discharge chamber 5e gradually move to the upper part of the discharge chamber 5e. An outlet 5c is provided at the center of the upper part of the discharge chamber 5e.
Bubbles in the discharge chamber 5e gather near the outlet 5c.

In this state, when the piston 6 moves upward in the Y direction as shown in FIG. 2(A), the liquid in the discharge chamber 5e is forced to be sent to the liquid feeding pipe 4 from the outlet 5c as described above. At the same time, the bubbles in the discharge port 5e are discharged to the downstream side together with the liquid.

In the metering pump 1, the inlet 5b
is provided at the lower end of the flow path 5a, and the outflow outlet 5c is provided at the lower end of the flow path 5a.
The inflow port 5b and the outflow port 5c are provided at the upper end of the piston 6, and the inflow port 5b and the outflow port 5c are linearly communicated via a through hole 6a that passes through the piston 6 in the vertical direction. Therefore, even if liquid containing air bubbles flows in, the air bubbles will not accumulate in the flow path 5a, and the air bubbles that flowed into the flow path 5a will be discharged downstream by the reciprocating movement of the piston 6 as described above. Ru.

[0040] Therefore, air bubbles do not remain in the flow path 5a of the metering pump 1, and fluctuations in the discharge amount per stroke due to the accumulation of air bubbles are prevented. As a result, the metering pump can discharge the air bubbles that have flowed into the pump to the outside, so that the subsequent discharge amount per stroke is stabilized, and a fixed amount of liquid can be accurately pumped regardless of the inflow of air bubbles.

A modification of the above embodiment is shown in FIGS. 3(A) and 3(B). In the metering pump shown in FIG. 3A, a tapered inclined surface 16 is provided at the peripheral edge of the lower opening 6a2 of the piston 6. Since this inclined surface 16 is formed to have a large diameter in the X direction and a small diameter in the Y direction, it has a shape that allows air bubbles flowing into the suction chamber 5d to easily collect in the through hole 6a.

Furthermore, in the metering pump shown in FIG. 3(B),
An inner wall 17 of the through hole 6a of the piston 6 is formed in a tapered shape. That is, the inner wall 17 of the through hole 6a is the lower opening 6a.
2 is inclined so that the diameter thereof is larger than that of the upper opening 6a1, and the shape is such that the air bubbles flowing into the suction chamber 5d can be easily sent upward.

In the above embodiment, the piston 6 is driven by the supply of compressed air, but the driving means is not limited to this. It may be driven mechanically.

[0044]

As described above, the metering pump of the present invention has an inlet at the lower end of the flow path penetrating upward and downward, an outlet at the upper end, and a piston having a through hole inserted into the flow path. Since the liquid is reciprocated, even if air bubbles are mixed in the liquid, the air bubbles that have flowed into the pump can be discharged from the outlet, and it is possible to prevent air bubbles from staying in the flow path. Therefore, it is possible to prevent the discharge amount per stroke from fluctuating due to stagnation in the air reservoir, and it is possible to accurately pump a fixed amount of liquid.

Furthermore, by providing the driving section outside the pump body, the pistons on the driving side and the driven side can be integrated, thereby simplifying the piston cylinder structure, resulting in a more compact configuration. Therefore, the installation space is reduced, and the device has the advantage of being able to be installed even in a narrow place.

[Brief explanation of the drawing]

FIG. 1 is a configuration diagram of a liquid feeding system to which an embodiment of a metering pump according to the present invention is applied.

FIG. 2 is a longitudinal sectional view for explaining the operation of the metering pump.

FIG. 3 is a longitudinal sectional view for explaining a modification of the metering pump of the present invention.

[Explanation of symbols]

1 Metering pump 2　Liquid storage tank 5　Pump body 5a Flow path 5b Inlet 5c Outlet 5d Suction chamber 5e Discharge chamber 6 Piston 6A Small diameter part 6B Large diameter part 6a Through hole 6f Cylinder part 7　Inflow side check valve 8 Outlet side check valve 9,10 Ball valve body 11 Four-way solenoid valve 15 Control section 16 Slope surface 17 Inner wall

Claims (1)

[Claims] 1. A pump body having a linear flow path extending vertically therein, an inlet provided at the lower end of the flow path, and an outlet provided at the upper end of the flow path; a piston that is slidably inserted into the flow path of the pump body and has a through hole therein that communicates the inflow port and the outflow port; and an inflow side check valve that opens and closes the inflow port from inside the flow path. A metering pump comprising: an outflow side check valve that opens and closes the through hole from the outflow side of the piston; and a drive unit that is provided outside the pump body and reciprocates the piston.