JP2000274374A - Small sized pump - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a small sized pump enhanced in shut-off properties. SOLUTION: This pump is provided with a discharge side liquid pooling chamber 9 disposed at the downstream side of a discharge side check valve in a casing, capable of storing the specified quantity of carrying fluid, a bulk- head 14 provided on the discharge passage 8 side of the discharge side liquid pooling chamber 9, equipped with a discharge port capable of being communicated with the discharge passage 8, and with a shut-off valve 15 provided at the discharge port of the bulkhead 14, communicated with the discharge passage 8 so as to let the reverse flow of the carrying fluid be prevented, and capable of being opened by the difference in pressure higher than that of the discharge side check valve 12.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a diaphragm-type small pump, and more particularly to a small-sized pump having a high discharge force without significantly impairing the flow rate of a carrier fluid, and having improved shutoff performance.

[0002]

2. Description of the Related Art Some conventional diaphragm-type small pumps use a vibrator made of a piezoelectric element (hereinafter referred to as a "piezoelectric vibrator"). A pump using a piezoelectric vibrator hermetically supports the outer peripheral portion of the piezoelectric vibrator through a fixing packing provided on the inner peripheral surface of the casing, and applies an AC voltage to the piezoelectric vibrator to apply the piezoelectric vibrator to the piezoelectric vibrator. By vibrating, the carrier fluid is sucked into the pump chamber from the suction port through the suction-side check valve, and the fluid sucked into the pump chamber is discharged from the discharge port through the discharge-side check valve. In general, in a diaphragm type small pump using a piezoelectric vibrator, a discharge amount of a carrier fluid per one time is small. For example, when a bimorph type piezoelectric element having a diameter of 25 mm is used as a drive source and driven by AC 100 V, Is about 0.01 cm ³ / Hz, and 0.5 cm ³ / sec at 50 Hz per second is obtained. As described above, since the discharge amount per discharge is extremely small in the small pump, the check valve needs to be configured to operate with a small pressure difference.

[0003]

However, the conventional small pump has a structure in which the check valve is opened with a small pressure difference, so that the carrier fluid must not flow naturally. The function (hereinafter, the function of preventing the spontaneous outflow of the carrier fluid when the pump is not operating is referred to as the "blocking property" of the pump) is insufficient, and as shown in FIG. If the discharge valve must be installed above the discharge ports of No. 15, there is a problem that the discharge valve is easily opened due to the difference in liquid gravity, the carrier fluid flows out spontaneously, and the blocking property is poor.

For this purpose, a tank 14 is provided with a small pump 15
To prevent the discharge valve from opening due to a difference in liquid gravity. Further, when the tank 14 is unavoidably installed above the discharge port of the small-sized pump 15 such as when using a drip, it is necessary to separately provide a closing valve 16 such as a solenoid valve, which increases cost. There was a problem.

[0005] Therefore, the present invention secures a constant flow rate and discharge pressure of the carrier fluid regardless of the height of the carrier fluid supply tank and the discharge port of the pump, and prevents the carrier fluid from flowing naturally due to the atmospheric pressure difference. It is an object of the present invention to provide a pump that is prevented, that is, has improved shut-off properties.

[0006]

In order to achieve the above object, according to the present invention, there is provided a small-sized pump, comprising: a casing (1); and a suction passage through which a carrier fluid flows into the casing (1). (2), a discharge channel (8) for discharging a carrier fluid from inside the casing (1), and a compartment having a suction port and a discharge port in the casing (1). A pump chamber (13) having therein a diaphragm for performing suction and discharge of the carrier fluid;
A suction-side check valve (6) provided at a suction port of the pump chamber (13) and communicating with the suction flow path (2) to prevent the backflow of the carrier fluid, and provided at a discharge port of the pump chamber (13). And a discharge-side check valve (12) communicating with the discharge flow path (8) side to prevent the backflow of the carrier fluid, a discharge-side check valve (12) in the casing (1). 1
A discharge-side liquid storage chamber (9) that is provided downstream of 2) and is capable of storing a predetermined volume of the carrier fluid, and a discharge-side liquid storage chamber (9) that is provided on the discharge flow path (8) side; A partition wall (14) having a discharge port capable of communicating with the flow path (8); and a discharge side provided at the discharge port of the partition wall (14) and communicating with the discharge flow path (8) to prevent backflow of the carrier fluid. A shutoff valve (15) that opens with a greater differential pressure than the check valve (12).

In such a configuration, at the time of suction of the carrier fluid, the suction action of the carrier fluid is not hindered and the suction-side check valve (6) is connected to the suction-side flow path (2).
, The carrier fluid flows into the pump chamber (13), and the carrier fluid flows into the discharge-side liquid reservoir (9) through the discharge-side check valve (12). Since the shut-off valve (15) that opens with a pressure difference greater than that of (1) is provided between the discharge-side liquid storage chamber (9) and the discharge flow path (8), the transfer fluid is increased at a high pressure due to the liquid gravity difference. Also, since the shut-off valve (15) is harder to open than the discharge-side check valve (12), it is possible to prevent the carrier fluid from spontaneously flowing out and improve the shut-off property. it can.

A small pump according to a second aspect of the present invention is provided in the casing (1) upstream of the suction check valve (6), and is capable of storing a predetermined volume of the carrier fluid. Liquid reservoir (3) and suction-side liquid reservoir (3)
And a diaphragm (40) made of a flexible sheet material provided so as to partition a part of the suction-side liquid storage chamber (3) into an air chamber (50) having a predetermined capacity. And

In this configuration, in addition to the effect of the first aspect, the pump chamber (1) is connected to the suction side flow path (2).
The pulsation generated when the carrier fluid flows into 3) is generated by the diaphragm (4).
Since the vibration is mitigated by the vibration 0), the flow velocity is leveled, the flow path resistance accompanying the pulsation is also leveled, and the flow rate change due to the resonance of the pipe due to the pulsation is suppressed. In addition, the diaphragm (4
0) keeps the volume of the air chamber (50) almost constant, so that changes in the flow rate and discharge pressure are suppressed even when the mounting posture of the pump changes.

According to a third aspect of the present invention, in the small pump according to the third aspect, the reciprocating movement of the diaphragm is performed by a piezoelectric vibrator.
And the piezoelectric vibrator (7) is driven by an AC power supply.

In such a configuration, in addition to the effects of the first and second aspects of the present invention, it can be easily used anywhere where an AC power source is provided. Further, even a viscous carrier fluid due to the vibration of the piezoelectric vibrator (7) can be easily discharged.

According to a fourth aspect of the present invention, in the small pump according to the fourth aspect, the shutoff valve (15) is made of an elastic material and has an umbrella type valve (60a).
It is characterized by being.

In such a configuration, the effects of the first to third aspects of the present invention can be achieved with a simple structure by using a check valve having an umbrella type structure.

According to a fifth aspect of the present invention, in the small pump according to the present invention, the shut-off valve (15) comprises, for example, an umbrella type valve (60a) shown in FIG. Each of the check valves (12) comprises an umbrella type valve (60b) shown in FIG. The umbrella type valve (60a) for the shutoff valve (15) includes a shaft portion (61a) and an umbrella portion (62a) provided at one end of the shaft portion (61a) and opened in an umbrella shape. (62a)
The thickness (ta) of the umbrella type valve (6
0b) is thicker than the thickness (tb) of the umbrella portion (62b), and the angle (α) between the umbrella portion (62a) and the shaft portion (61a).
Is smaller than the angle (β) between the umbrella portion (62b) and the shaft portion (61b) of the umbrella type valve (60b) on the suction side and the discharge side, and the umbrella has a slightly narrowed shape. . On the other hand, in the above umbrella type valve (60b), as shown in FIG. 3, for example, the thickness of the umbrella portion (62b) is thinner than that of the umbrella type valve (60a) for the shutoff valve (15). The umbrella is formed so as to have a smaller shape than (60a).

In such a configuration, in addition to the effect of the invention described in claim 4, an umbrella type valve (60a) for the shut-off valve (15) is provided.
Can be further enhanced, so that the blocking performance can be improved with a simple design.

The small pump according to claim 6 of the present invention is characterized in that the shut-off valve (15) is a reed valve (63).

According to a seventh aspect of the present invention, the shut-off valve (15) is a spring valve (64).

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a longitudinal sectional view showing an embodiment of the small pump of the present invention. FIG. 2 shows an umbrella type valve used as a shut-off valve of the small pump of the present invention.
Fig. 3 is a longitudinal half sectional view of the same, (b) is a longitudinal half sectional view showing a state where an umbrella type valve is mounted, and Fig. 3 is used as a suction side check valve and a discharge side check valve of the small pump of the present invention. (A) is a longitudinal half-sectional view thereof, (b) is a longitudinal half-sectional view showing a state where the umbrella-type valve is mounted, and FIG. 4 is a shut-off valve of the small pump of the present invention. Indicates the reed valve used as
(A) is a plan view, (b) is a side view, and FIG. 5 is a plan view of a spring valve used as a shut-off valve of the small-sized pump of the present invention.

FIG. 1 shows a small pump according to an embodiment of the present invention.
As shown in FIG. 1, basically, a casing 1, a suction channel 2 for flowing a carrier fluid into the casing 1, a discharge channel 8 for discharging a carrier fluid from the casing 1, and a suction port in the casing 1. And a pump chamber 13 which is provided as a compartment having a discharge port and has a diaphragm therein for reciprocating vibration by a drive source and for sucking and discharging the above-mentioned carrier fluid.
And provided in the suction port of the pump chamber 13,
And a suction-side check valve 6 for preventing backflow of the carrier fluid, and a discharge passage 8 provided at a discharge port of the pump chamber 13.
Check valve 1 for preventing backflow of the carrier fluid
2 is provided. Further, a suction-side liquid storage chamber 3 capable of storing a predetermined volume of the carrier fluid is provided upstream of the suction-side check valve 6 in the casing 1, and a discharge-side liquid capable of storing the predetermined volume of the carrier fluid. A reservoir 9 is provided in the casing 1 on the downstream side of the discharge-side check valve 12.

In the small diaphragm pump according to the present embodiment, the reciprocating movement of the diaphragm is performed by the piezoelectric vibrator 7. As the piezoelectric vibrator 7, an element such as a unimorph or a bimorph that applies a change in bending of a piezoelectric body is used, and is driven by an AC power supply.

With this configuration, the carrier fluid is sucked from the suction-side check valve 6 while the piezoelectric vibrator 7 is deformed downward, and the carrier fluid is deformed upward and the discharge-side check valve is discharged. The carrier fluid is continuously discharged by the reciprocating motion of the piezoelectric vibrator 7 after being discharged from the liquid crystal 12.

The present invention comprises a partition wall 14 provided on the discharge channel 8 side of the discharge-side liquid storage chamber 9 and having a discharge port which can communicate with the discharge channel 8, and a discharge port provided on the discharge port of the partition wall 14. A discharge-side check valve 1 communicating with a passage 8 to prevent the backflow of the carrier fluid.
And a shutoff valve 15 that opens with a differential pressure greater than 2. The shut-off valve 15 has a structure that is harder to open than the discharge-side check valve 12 in order to enhance the shut-off property.

In one embodiment of the present invention, the suction side check valve 6, the discharge side check valve 12, and the shutoff valve 15 are respectively
For example, an umbrella type valve made of an elastic material made of a flexible rubber material such as silicon rubber, butyl rubber, and fluorine rubber is used.

The umbrella type valve 60a for the shut-off valve 15 is shown in FIG.
As shown in (a), the shaft portion 61a and an umbrella portion 62a provided on one end side of the shaft portion 61a and opened in an umbrella shape, and the thickness ta of the umbrella portion 62a is set on the suction side and the discharge side umbrella. The thickness of the umbrella portion 62b of the mold valve 60b is greater than the thickness tb of the umbrella portion 62b, and the umbrella portion 6
The angle α between the shaft portion 2a and the shaft portion 61a is equal to the suction side umbrella type valve 6.
0b is smaller than the angle β formed between the umbrella portion 62b and the shaft portion 61b, and the umbrella has a slightly narrowed shape. The umbrella 62a has a diameter of about 10 mm and a thickness of about 2 to 3 mm. In addition, on the side of the shaft portion 61a opposite to the umbrella portion 62a side, there is a large diameter portion 63 having a slightly larger shaft diameter to prevent the discharge port of the partition wall 14 from slipping out at the time of mounting.

When the partition 14 is attached to the discharge port, FIG.
As shown in (b), the umbrella portion 62a is perpendicular to the shaft portion 61a at a position where at least a part of the front end portion f intersects the surface of the umbrella portion 62a on the shaft portion 61a side and the surface of the shaft portion 61a. It is on the line, the angle α between the umbrella portion 62a and the shaft portion 61a is larger than before the attachment to the partition wall 14, and is attached in a state where the angle α is as close to 90 ° as possible.
It will be mounted with the side warped. When the pressure due to the carrier fluid in the liquid storage chamber 9 is applied, the umbrella portion 62a
When the carrier fluid pushes up the umbrella portion 62a from below in the direction of the arrow above the outlet 14a disposed in the middle of the umbrella, the umbrella portion 62a is lifted up and the umbrella valve 60a open.

On the other hand, as shown in FIG. 3A, an umbrella type valve 60b for the suction-side check valve 6 and the discharge-side check valve 12 has a shaft 61b and one end of the shaft 61b. Provided,
The umbrella portion 62b is opened in an umbrella shape, the thickness ta of the umbrella portion 62b is thinner than the thickness ta of the umbrella type valve 60a for the shutoff valve 15, and the angle β formed between the umbrella portion 62b and the shaft portion 61b is ,
The umbrella-shaped valve 60a, which is the shutoff valve 15, is formed so as to be larger than the angle α formed between the umbrella portion 62a and the shaft portion 61a and to have a shape with a smaller umbrella than the shutoff valve 15.
The umbrella portion 62b has a diameter of about 10 mm and a thickness of about 1 mm to about 2 mm.

When the pump chamber 13 is attached to the suction port or the discharge port, as shown in FIG. 3 (b), at least a part of the front end f of the umbrella section 62b has a shaft section 61b of the umbrella section 62b.
The angle α between the umbrella portion 62b and the shaft portion 61b is larger than before mounting on the partition wall 14 and is on the line perpendicular to the shaft portion 61b from the position where the side surface and the surface of the shaft portion 61b intersect.で
2b is mounted with its tip f side warped. In this case, the thickness tb of the umbrella portion 62b of the umbrella valve 60b for the suction-side check valve 6 and the umbrella-type check valve 12 for the discharge-side check valve 12 is substantially the same, even though the diameter of the umbrella portion is substantially the same.
Is smaller than the thickness ta of the umbrella portion 62a in the umbrella-type valve 60a, and the angle β between the umbrella portion 62b and the shaft portion 61b is greater than the angle α between the umbrella portion 62a and the shaft portion 61a in the umbrella-type valve 60a. As is clear from the comparison between FIG. 3B and FIG. 2B, the umbrella valve 60b
The degree of warping of the tip f of the umbrella 62b is smaller than that of the tip f of the umbrella 62a in the umbrella-type valve 60a. When pressure due to the carrier fluid is applied, the umbrella valve 6
0a, the carrier fluid passes through the outlet 13a disposed in the middle of the umbrella portion 62b from below to draw the umbrella portion 62b from below.
When the carrier fluid is pushed up in a direction indicated by the arrow (b) in FIG. 3B (upstream direction) and has a pushing force equal to or higher than a predetermined pressure smaller than that of the umbrella valve 60a, the umbrella portion 62b is lifted and the umbrella valve 60b is opened. As described above, the normal umbrella type valve 60b on the suction side and the discharge side has a small change in volume of the pump chamber 13 due to the reciprocating vibration per one time of the piezoelectric vibrator 7, so that a small pressure difference generated at this time causes A flexible structure is taken to operate.

As described above, the umbrella type valve 60a for the shutoff valve 15
Since the thickness of the umbrella portion 62a is thicker than that of the umbrella-type valve 60b on the suction side and the discharge side and the constriction of the umbrella portion 62a is larger, the umbrella portion 62a is conveyed as compared with the normal umbrella-type valve 60b on the suction side or the discharge side. The resistance of the fluid flowing out also increases, and the blocking performance increases. Specifically, as shown in FIGS. 2 (a) and 3 (a), a normal umbrella-type valve 60b serving as the check valves 6 and 12 on the suction side and the discharge side has a diameter of 10 mm and has an umbrella portion. The height is 1 mm, the thickness of the base of the bent portion of the umbrella is 0.95 mm, and the umbrella type valve 60a for the shutoff valve 15 has a diameter of 10 mm.
Assuming that the height of the umbrella portion is 1.5 mm and the thickness of the base of the bent portion of the umbrella is 1.35 mm, even if the transport liquid supply tank is 60 cm above the discharge port, the transport liquid leaking from the discharge port can be prevented. The amount is 50 cc / min or more for only the check valves 6 and 12 on the suction side and the discharge side, whereas the amount is 50 cc / min or more.
Is provided, it is about 5 cc / min or less.

The check valve which can be combined so that the check valves 6 and 12 on the suction side and the discharge side are opened at a low differential pressure and the shutoff valve 15 is opened at a high differential pressure is the above-mentioned umbrella type valve. In addition, there are a reed valve 63 shown in FIG. 4 and a spring valve 64 shown in FIG. In order to achieve the object of the present invention, irrespective of these valves, any valve can be used as long as the differential pressure of the shut-off valve 15 can be higher than that of the suction-side or discharge-side check valves 6, 12. It may be of any shape.

The reed valve 64 shown in FIG. 4 has a central portion on the lower surface side inclined at one end of a reed 64c made of a long plate-shaped elastic body, in accordance with the discharge port and the suction port of the pump chamber 13 so as to be convex. A seal seat 64a is provided.
c is an inclined portion 64d that is slightly bent from a flat surface on the side opposite to the seal seat 64a side. It is fixed in the pump chamber 13 by fixing means such as a screw through a mounting hole 64e provided at the end of the inclined portion 64d, and the discharge port and the suction port of the pump chamber 13 are shut off by the seal seat 64a. ing. Reference numeral 64b denotes a stopper for fixing the seal seat 64a to the lead 64c.
e is an opening for fixing the reed valve 64 to the casing 1. By changing the bending angle, thickness, and rigidity of the lead 64c, the differential pressure can be changed to change the blocking performance. Further, since the reed valve 64c is bent at the inclined portion 64d, the seal seat 64
By changing the height of “a”, the blocking property can be changed.

The spring valve 65 shown in FIG. 5 has a peripheral portion mounted on a discharge side spring valve mounting hole of the pump chamber 13 by a retaining ring (not shown). Only the pressure of the carrier fluid is applied, the central portion is lifted, and from the void portion 65a,
The carrier fluid is discharged. In the case of the spring valve 65, the cutoff property can be improved by increasing the thickness and rigidity, and by narrowing the width of the gap portion 65a which has been narrowed to three places.

In the present embodiment, a flexible sheet material is provided in the suction-side liquid storage chamber 3 so as to partition a part of the suction-side liquid storage chamber 3 into an air chamber 50 having a predetermined capacity. Is provided.

As described above, by providing the diaphragm 40 that partitions the air chamber 50 in the suction-side liquid storage chamber 3, pulsation generated when the carrier fluid flows from the suction-side flow path 2 into the pump chamber 13 is reduced. Since the vibration is mitigated by the vibration of the diaphragm 40, the flow velocity is leveled, the flow path resistance accompanying the pulsation is also leveled, and the flow rate change due to the resonance of the pipe due to the pulsation is suppressed. Further, since the volume of the air chamber 50 is kept almost constant by the diaphragm 40, the change in the flow rate and the discharge pressure is suppressed even when the mounting posture of the pump changes.

[0034]

Embodiments of the present invention will be described below.
In the embodiment of the present invention, in the diaphragm type small pump using the piezoelectric vibrator 7, the suction side and the discharge side check valves 6, 12 are provided with the umbrella type valve 60b and the shutoff valve 15 having the shapes shown in FIG. An umbrella type valve 60 having the shape shown in FIG.
a was used. As a comparative example, both the suction and discharge-side check valves 6 and 12 have an umbrella type valve 6 having a normal shape shown in FIG.
0b and a conventional small pump without the shut-off valve 15 was manufactured. As to the degree of “blocking property” of each pump, as shown in FIG. 6, the pump 14 storing the carrier fluid is positioned higher than the position of the discharge-side check valve of each pump 15. The height from the liquid level of the carrier fluid in the tank 14 to the outlet of the pump when the carrier fluid naturally flows out of the tank 14 from the discharge side check valve of each pump when the pumps are not operating. Hs was measured and evaluated quantitatively by comparing this Hs value for each pump. In other words, the greater the Hs value, the higher the "blocking performance" of the pump. The “discharge pressure” in Table 1 refers to the pressure at which the carrier fluid flows out when the discharge valve opens.

[0035]

[Table 1]

(Results) As shown in Table 1, there was no significant difference in the flow rate and the discharge pressure in the example compared to the comparative example, but it was found that the blocking performance was increased about 20 times. Specifically, as shown in FIG. 7, the leakage amount for the blocking performance (Hs) is higher in the embodiment than in the comparative example.
It can be seen that the leakage amount is extremely small even when The amount of leakage when the height of the head of the example was 90 cm was equivalent to the height of 4 cm of the head of the comparative example, and it was found that the optimum discharge flow rate was maintained.

[0037]

According to the present invention, when sucking a carrier fluid,
The suction operation of the carrier fluid is not hindered, and the suction operation is performed via the suction-side check valve (6) from the suction-side flow path (2).
The carrier fluid flows into the pump chamber (13), and the carrier fluid flows into the discharge-side liquid reservoir (9) via the discharge-side check valve (12). Since the shut-off valve (15) having a large pressure is provided, the shut-off valve (15) opens more than the discharge-side check valve (12) even when the carrier fluid flows in at a high pressure due to the liquid gravity difference. Because of the difficulty, it is possible to prevent the carrier fluid from spontaneously flowing out, and to improve the blocking property.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing one embodiment of a small pump of the present invention.

FIG. 2 shows an umbrella type valve used as a shut-off valve of the small pump of the present invention, wherein (a) is a longitudinal half sectional view thereof, and (b).
FIG. 2 is a vertical half sectional view showing a state where an umbrella type valve is mounted.

3 shows an umbrella type valve used as a suction side check valve and a discharge side check valve of the small pump of the present invention, (a) is a longitudinal half sectional view, (b) is an umbrella type valve FIG. 3 is a vertical half sectional view showing a mounted state.

4A and 4B show a reed valve used as a shut-off valve of the small pump of the present invention, wherein FIG. 4A is a plan view and FIG. 4B is a side view.

FIG. 5 is a plan view showing a spring valve used as a shut-off valve of the small pump of the present invention.

FIG. 6 is a schematic diagram illustrating the blocking property.

FIG. 7 is a diagram showing a difference between an embodiment of the present invention and a comparative example with respect to the relationship between the blocking performance and the leakage amount.

[Explanation of symbols]

 2 Suction flow path 3 Suction side liquid storage chamber 6 Suction side check valve 7 Piezoelectric vibrator 8 Discharge flow path 9 Discharge side liquid storage chamber 12 Discharge side non-return valve 13 Pump chamber 14 Partition wall 15 Shutoff valve 40 Diaphragm 60a, 60b Umbrella Mold valve 61a, 61b Shaft 62a, 62b Umbrella f End of umbrella

Claims (7)

[Claims] A casing (1) and a casing (1)
A suction channel (2) for flowing a carrier fluid into the inside, and a discharge channel (8) for discharging a carrier fluid from the casing (1).
And a pump chamber (13) which is provided in the casing (1) as a compartment having a suction port and a discharge port, and has a diaphragm therein for reciprocating vibration by a drive source and for sucking and discharging the carrier fluid. A suction-side check valve (6) provided at a suction port of the pump chamber (13) and communicating with the suction flow path (2) to prevent the backflow of the carrier fluid;
3) a small pump provided at the discharge port and having a discharge check valve (12) communicating with the discharge flow path (8) and preventing the backflow of the carrier fluid; A discharge-side liquid storage chamber (9) provided downstream of the discharge-side check valve (12) and capable of storing a predetermined volume of the carrier fluid; and a discharge flow path of the discharge-side liquid storage chamber (9). The partition (14) provided on the 8) side and having a discharge port capable of communicating with the discharge flow path (8).
And a shutoff valve (15) provided at the discharge port of the partition wall (14) and communicating with the discharge flow path (8) to prevent the backflow of the carrier fluid and open with a larger differential pressure. And a small pump. 2. A suction side liquid storage chamber (3) provided in the casing (1) upstream of the suction side check valve (6) and capable of storing a predetermined volume of the carrier fluid; A diaphragm (4) made of a flexible sheet material provided in the reservoir (3) so as to partition a part of the suction-side liquid reservoir (3) into an air chamber (50) having a predetermined capacity.
2. The small pump according to claim 1, further comprising: 3. The small pump according to claim 1, wherein the reciprocating movement of the diaphragm is performed by a piezoelectric vibrator, and the piezoelectric vibrator is driven by an AC power supply. 4. The small pump according to claim 1, wherein the shut-off valve (15) is an umbrella type valve (60a) made of an elastic material. 5. The suction-side check valve (6) and the discharge-side check valve (12) are both umbrella-type valves (60b), and the umbrella-type valve (60a) for the shut-off valve (15) is a shaft part. (61
a) and an umbrella portion (62a) provided at one end of the shaft portion (61a) and opened in an umbrella shape. The thickness (ta) of the umbrella portion (62a) is umbrella-shaped on the suction side and the discharge side. Thickness (tb) of umbrella part (62b) of valve (60b)
And the angle (α) between the umbrella portion (62a) and the shaft portion (61a) is larger than that of the umbrella-type valve (60
The small pump according to claim 4, characterized in that the angle (β) between the umbrella portion (62b) and the shaft portion (61b) in b) is smaller and the umbrella is slightly narrowed. 6. The small pump according to claim 1, wherein the shut-off valve is a reed valve. 7. The small pump according to claim 1, wherein the shut-off valve (15) is a spring valve (65).