WO2013121463A1

WO2013121463A1 - Pump device and pump system

Info

Publication number: WO2013121463A1
Application number: PCT/JP2012/001023
Authority: WO
Inventors: 勇治野々村; 常男大坂; 竜二糸山
Original assignee: アルバック機工株式会社
Priority date: 2012-02-16
Filing date: 2012-02-16
Publication date: 2013-08-22
Also published as: US20160003228A1; CA2863775A1; EP2816233B1; EP2816233A4; EP2816233A1

Abstract

[Problem] To provide a pump device configured so that the discharge of fluid can be limited while the operation of the pump device is stopped. [Solution] A pump device (3) is provided with a casing (10), a movable member (30), a suction valve (41), a discharge valve (42), and a valve mechanism (50). The casing (10) has a pump chamber (100) which can connect to a suction opening (101) and to a discharge opening (102). The movable member (30) can move within the casing (10) and alternately performs the suction of fluid into the pump chamber (100) and the discharge of the fluid from the pump chamber (100). The discharge valve (42) is mounted between the pump chamber (100) and the discharge opening (102) and permits fluid having a pressure higher than or equal to a first pressure to flow from the pump chamber (100) toward the discharge opening (102). The valve mechanism (50) is mounted to the casing (10) and limits the flow of fluid flowing from the suction opening (101) toward the discharge opening (102), the fluid having a pressure lower than or equal to a second pressure which is higher than the first pressure.

Description

Pump device and pump system

The present invention relates to a pump device used as, for example, a booster blower or a booster pump, and a pump system including the pump device.

2. Description of the Related Art Pump devices called booster blowers or booster pumps are widely known as devices that raise a gas such as fuel gas or oxygen, or a liquid such as cooling water or hydraulic oil to a desired pressure. For this type of pump device, a roots pump, a diaphragm pump, or the like is used. For example, Patent Document 1 listed below describes a diaphragm pump used as a booster for fuel gas in a fuel cell system.

JP 2009-47084 A

Conventional pressure boosters did not have the function of reducing the fluid pressure introduced and discharging. For this reason, in a pump system in which a pressure source that supplies fluid of a predetermined pressure or higher is connected to the suction port of the booster blower, the fluid introduced to the suction port when the booster blower is stopped is discharged from the booster blower. Depending on the situation, there was a possibility of causing a problem in the system.

In view of the circumstances as described above, an object of the present invention is to provide a pump device and a pump system capable of restricting fluid discharge when operation is stopped.

In order to achieve the above object, a pump device according to an aspect of the present invention includes a casing, a movable member, a first valve, a second valve, and a third valve.
The casing includes a suction port, a discharge port, and a pump chamber that can communicate with the suction port and the discharge port.
The movable member is movable in the casing, and alternately sucks fluid into the pump chamber and discharges the fluid from the pump chamber.
The first valve is attached between the suction port and the pump chamber, and allows the fluid to flow from the suction port to the pump chamber.
The second valve is attached between the pump chamber and the discharge port, and allows the fluid flow from the pump chamber to the discharge port when the fluid in the pump chamber is equal to or higher than the first pressure. Allow.
The third valve is attached to the casing, and when the fluid between the suction port and the discharge port is equal to or lower than a second pressure larger than the first pressure, the suction port to the discharge port. Restrict the flow of fluid toward

In order to achieve the above object, a pump system according to an embodiment of the present invention includes a pump device, a pressure source, and a processing unit.
The pump device includes a casing, a movable member, a first valve, a second valve, and a third valve.
The casing includes a suction port that communicates with the pressure source, a discharge port that communicates with the processing unit, and a pump chamber that can communicate with the suction port and the discharge port.
The movable member is movable in the casing, and alternately sucks fluid into the pump chamber and discharges the fluid from the pump chamber.
The first valve is attached between the suction port and the pump chamber, and allows the fluid to flow from the suction port to the pump chamber.
The second valve is attached between the pump chamber and the discharge port, and allows the fluid to flow from the pump chamber toward the discharge port at a pressure equal to or higher than the first pressure.
The third valve is attached to the casing and restricts the flow of the fluid from the suction port toward the discharge port and below a second pressure greater than the first pressure.
The pressure source is connected to the suction port, and supplies a fluid having the second pressure or less to the pump device.
The processing unit is connected to the discharge port and processes fluid discharged from the pump device.

It is a figure showing the outline of the pump system concerning one embodiment of the present invention. It is sectional drawing of the pump apparatus which concerns on one Embodiment of this invention. It is a cross-sectional perspective view which shows the structure of the valve mechanism integrated in the said pump apparatus. It is sectional drawing of the said valve mechanism. It is one experimental result which shows the time change of the discharge flow rate of a pump apparatus when the driving | operation and stop of the said pump apparatus are repeated. It is the piping block diagram used for the experiment shown in FIG. It is a figure explaining one effect | action of the said pump apparatus. It is sectional drawing of the pump apparatus which concerns on the 2nd Embodiment of this invention. It is a partial exploded perspective view of the pump apparatus which concerns on the 3rd Embodiment of this invention. It is a figure explaining an effect | action of the pump apparatus shown in FIG. It is a perspective view of the pump apparatus which concerns on the 4th Embodiment of this invention. It is principal part sectional drawing of the pump apparatus shown in FIG. It is a front view of the pump apparatus shown in FIG. It is a rear view of the pump apparatus shown in FIG. It is a top view of the pump apparatus shown in FIG. It is a bottom view of the pump apparatus shown in FIG. It is a right view of the pump apparatus shown in FIG. It is a left view of the pump apparatus shown in FIG.

A pump device according to an embodiment of the present invention includes a casing, a movable member, a first valve, a second valve, and a third valve.
The casing includes a suction port, a discharge port, and a pump chamber that can communicate with the suction port and the discharge port.
The movable member is movable in the casing, and alternately sucks fluid into the pump chamber and discharges the fluid from the pump chamber.
The first valve is attached between the suction port and the pump chamber, and allows the fluid to flow from the suction port to the pump chamber.
The second valve is attached between the pump chamber and the discharge port, and allows the fluid flow from the pump chamber to the discharge port when the fluid in the pump chamber is equal to or higher than the first pressure. Allow.
The third valve is attached to the casing, and when the fluid between the suction port and the discharge port is equal to or lower than a second pressure larger than the first pressure, the suction port to the discharge port. Restrict the flow of fluid toward

In the above pump device, the movable member periodically changes the volume of the pump chamber, thereby alternately sucking the fluid into the pump chamber and discharging the fluid from the pump chamber. The fluid may be a gas or a liquid. When the fluid is sucked, the fluid is introduced from the suction port into the pump chamber through the first valve. When the fluid is discharged, the fluid introduced into the pump chamber is compressed to a pressure equal to or higher than the first pressure by the movable member in the pump chamber, so that the second valve is opened and discharged from the discharge port. By repeating the above operation, the fluid is discharged from the discharge port at a pressure equal to or higher than the first pressure.

The second valve opens when the pressure in the pump chamber reaches or exceeds the first pressure, and allows the fluid to flow from the pump chamber to the discharge port. Therefore, for example, when the pump device is stopped, if fluid is introduced into the pump chamber from the suction port at a pressure equal to or higher than the first pressure, the second valve is opened and a fluid flow toward the discharge port is formed. become.

Therefore, the pump device has a third valve. The third valve restricts the flow of fluid below the second pressure that is greater than the first pressure. Accordingly, when the pump device is stopped, even if a fluid having a pressure not lower than the first pressure and not higher than the second pressure is introduced from the suction port into the pump chamber, the flow of the fluid is inhibited by the third valve, and the discharge is prevented. The discharge of fluid from the outlet is suppressed. Thereby, inadvertent discharge of the fluid at the time of operation stop is suppressed.

Further, according to the above pump device, since inadvertent discharge of the fluid when the pump device is stopped can be suppressed, the pump device can also be applied to a pump system in which a fluid pressure source is connected to the suction port. As a result, it is possible to eliminate the possibility that the system may malfunction due to fluid leaking from the discharge port when the operation is stopped.

The second pressure can be set as appropriate, and is set based on, for example, the pressure of the fluid introduced into the suction port or the allowable flow rate of the fluid discharged in the operation stop state. “Limiting the flow” includes the meaning of “blocking the flow” and the meaning of “decreasing the flow rate without blocking the flow”.

The third valve is attached to the casing. The third valve may be attached to the suction port side or may be attached to the discharge port side. In one embodiment, the third valve is disposed closer to the discharge port than the second valve. Thereby, the stable pump performance can be ensured without obstructing the flow of the fluid introduced into the pump chamber.

The third valve may have a structure that can completely block the flow of fluid below the second pressure, and the opening degree is stepwise between the first pressure and the second pressure. The structure may change. In the former case, the third valve can be constituted by, for example, an electromagnetic valve.

On the other hand, in the latter case, the third valve employs a valve structure in which the opening degree increases in accordance with the pressure. For example, the third valve includes a valve seat, and a valve member that can be seated on the valve seat and whose opening degree changes continuously according to a pressure not lower than the first pressure and not higher than the second pressure. As a valve having such a valve structure, for example, an umbrella valve is applicable. Thereby, low flow control of the fluid discharged from the said pump apparatus is attained.

The casing may further include a space part in which a part of the flow path communicating between the second valve and the third valve is expanded. The space portion functions as a buffer space for buffering the pulsation of the discharged fluid. Thereby, the pulsation of the fluid can be reduced, and the fluid can be discharged at a stable flow rate. In addition, in the case where the drive of the pump device is controlled based on the discharge flow rate, stable drive control of the pump device is possible.

The pump device can be configured with a diaphragm pump. In this case, the movable member includes a deformable diaphragm that partitions the pump chamber. Thereby, a small pump device can be provided.

A pump system according to an embodiment of the present invention includes a pump device, a pressure source, and a processing unit.
The pump device includes a casing, a movable member, a first valve, a second valve, and a third valve.
The casing includes a suction port that communicates with the pressure source, a discharge port that communicates with the processing unit, and a pump chamber that can communicate with the suction port and the discharge port.
The movable member is movable in the casing, and alternately sucks fluid into the pump chamber and discharges the fluid from the pump chamber.
The first valve is attached between the suction port and the pump chamber, and allows the fluid to flow from the suction port to the pump chamber.
The second valve is attached between the pump chamber and the discharge port, and allows the fluid to flow from the pump chamber toward the discharge port at a pressure equal to or higher than the first pressure.
The third valve is attached to the casing and restricts the flow of the fluid from the suction port toward the discharge port and below a second pressure greater than the first pressure.
The pressure source is connected to the suction port, and supplies a fluid having the second pressure or less to the pump device.
The processing unit is connected to the discharge port and processes fluid discharged from the pump device.

According to the above pump system, even when a fluid having a pressure not lower than the first pressure and not higher than the second pressure is introduced from the pressure source into the pump chamber when the pump device is stopped, the third valve causes the fluid to flow. The flow is hindered, and the discharge of fluid from the discharge port is restricted. Thereby, inadvertent discharge of the fluid at the time of operation stop is suppressed. In addition, it is possible to eliminate the possibility that the system may malfunction due to fluid leaking from the discharge port when the operation is stopped.

The processing unit is not particularly limited, and includes various devices for generating energy and power using a fluid discharged from a pump device, such as a reformer, a combustor, a generator, a cylinder device, and various engines.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

<First Embodiment>
[Pump system]
FIG. 1 is a diagram showing an outline of a pump system according to an embodiment of the present invention. The pump system 1 according to the present embodiment includes a pressure source 2, a pump device 3, a processing unit 4, and a control unit 5.

The pressure source 2 is connected to the suction side (primary side) of the pump device 3, and the processing unit 4 is connected to the discharge side (secondary side) of the pump device 3. The pressure source 2 may be a container such as a tank or a cylinder that contains a fluid (gas or liquid) having a predetermined pressure, or may be a pressure generation source such as a compressor. The pump device 3 functions as a booster blower or a booster pump that increases the fluid of the pressure P1 introduced from the pressure source 2 to a predetermined pressure P2 and supplies the fluid to the processing unit 4. The processing unit 4 processes the fluid supplied from the pump device 3 to generate energy, power, and the like. The control unit 5 controls the operation of the pump device 3, but may control the entire system including the processing unit 4.

The pump system 1 is applied to a fuel cell system, for example. In this case, the pressure source 2 corresponds to a fuel tank, and the pump device 3 boosts the fuel gas (for example, city gas (methane), LPG (liquefied propane gas)) and supplies it to the processing unit 4. The processing unit 4 includes a reformer that converts fuel gas into hydrogen, a fuel cell that stores hydrogen, a power generation unit that reacts hydrogen and oxygen, and the like.

[Pump device]
Next, the details of the pump device 3 will be described with reference to FIG. FIG. 2 is a cross-sectional view showing the structure of the pump device 3. In the present embodiment, the pump device 3 is constituted by a diaphragm pump.

The pump device 3 has a metal casing 10 and a drive unit 20. The casing 10 includes a pump body 11, a pump head 12, and a pump head cover 13. The drive unit 20 includes a motor 21 and a motor case 22.

The pump body 11 forms an operation space 105 in which the movable member 30 is accommodated in the casing 10. The movable member 30 includes a diaphragm 31, a fixture 32 fixed to the diaphragm 31, and a connecting rod 33 that couples the fixture 32 to the motor 21.

The diaphragm 31 is formed of a disc-shaped rubber material, and the peripheral edge thereof is sandwiched between the pump body 11 and the pump head 12. The fixture 32 is fixed to the central portion of the diaphragm 31, and is composed of a plurality of parts assembled so as to sandwich the diaphragm 31 from above and below. The connecting rod 33 is integrated with the fixture 32 so as to penetrate the central portion of the diaphragm 31. The connecting rod 33 is connected to the peripheral surface of the eccentric cam 35 attached to the rotating shaft 210 of the motor 21 via the bearing 34.

The pump head 12 has a suction port 101 and a discharge port 102 and is disposed on the upper surface of an annular pedestal 110. The pedestal 110 is attached to the opening end of the upper portion of the pump body 11 and sandwiches the peripheral edge of the diaphragm 31 together with the pump head 12. The pump head 12 forms a pump chamber 100 between the diaphragm 31 and the pump head 12.

The pump head 12 has a suction passage T1 that communicates between the suction port 101 and the pump chamber 100, and a discharge passage T2 that communicates between the pump chamber 100 and the discharge port 102. The pump chamber 100 can communicate with the suction port 101 and the discharge port 102 via the suction passage T1 and the discharge passage T2, respectively. A suction valve 41 (first valve) and a discharge valve 42 (second valve) are respectively attached to the suction passage T1 and the discharge passage T2.

The suction valve 41 is attached to the pump head 12 so as to close the suction hole h1 that forms the suction passage T1. The suction valve 41 is constituted by a reed valve attached to the end of the suction hole h1 facing the pump chamber 100, and allows the flow of fluid from the suction port 101 toward the pump chamber 100. The valve opening pressure of the suction valve 41 (minimum pressure required to open the suction valve 41) is not particularly limited, and has a valve opening pressure at which a predetermined flow rate of gas is introduced into the pump chamber 100 during operation of the pump device. It only has to be. Accordingly, the valve opening pressure of the suction valve 41 may be a pressure lower than the pressure of the gas supplied from the pressure source 2 to the pump device 3.

On the other hand, the discharge valve 42 is attached to the pump head 12 so as to close the discharge hole h2 forming the discharge passage T2. The discharge valve 42 is constituted by a reed valve attached to the end of the discharge hole h <b> 2 on the side opposite to the pump chamber 100, and allows the flow of fluid from the pump chamber 100 toward the discharge port 102. The valve opening pressure of the discharge valve 42 (minimum pressure required to open the discharge valve 42) is not particularly limited, and is set to a pressure at which a target discharge pressure can be obtained. Is set to a large pressure (first pressure).

The pump head cover 13 is attached to the top of the pump head 12. The suction passage T1 and the discharge passage T2 are formed by combining the pump head 12 and the pump head cover 13, respectively. The pump body 11, the pump head 12, and the pump head cover 13 are integrally fixed using a plurality of screw members B.

The motor 21 is composed of a DC brushless motor capable of controlling the rotational speed, and is accommodated in a cylindrical motor case 22. The motor 21 includes a rotating shaft 210, a stator 211, and a rotor 212. The stator 211 is fixed to the inner surface of the motor case 22, and the rotor 212 is fixed around the rotating shaft 210. The rotating shaft 210 is supported by the motor case 22 via

bearings

23 and 24, and is attached to the rotation center of the eccentric cam 35 at the tip thereof.

The eccentric cam 35 is formed so that the rotation center thereof is eccentric with respect to the inner race of the bearing 34. Accordingly, when the rotating shaft 210 rotates around the axis by driving the motor 21, the eccentric cam 35 rotates together with the rotating shaft 210, so that the movable member 30 reciprocates in the vertical direction inside the operation space 105. Thereby, the volume of the pump chamber 100 changes periodically, and a predetermined pump function is obtained. The reciprocating amount (stroke amount) of the movable member 30 is determined by the eccentric amount of the eccentric cam 35.

The pump device 3 further includes a valve mechanism 50 (third valve). In the present embodiment, the valve mechanism 50 is attached to the discharge port 102. The valve mechanism 50 has a function of restricting the outflow of gas from the gas discharge port 102 when the operation of the pump device 3 is stopped.

FIG. 3 is a cross-sectional perspective view showing the configuration of the valve mechanism 50, and FIG. 4 is a cross-sectional view thereof. The valve mechanism 50 includes a rubber valve member 51 and a metal housing 52 that houses the valve member 51.

The housing 52 has a first end 521 connected to the discharge port 102 of the casing 10 and a second end 522 connected to a conduit (not shown) communicating with the processing unit 4. A seal ring 54 is mounted around the first end portion 521, and the first end portion 521 is hermetically attached to the inside of the discharge port 102 by the seal ring 54.

Inside the housing 52, an internal passage 523 communicating between the first end 521 and the second end 522 is formed. A wall portion 53 having a central portion and a plurality of holes 531 around the center portion is formed perpendicularly to the wall surface of the internal passage 523 at the substantially central portion of the internal passage 523, and the first end is formed through these holes 531. The portion 521 and the second end portion 522 can communicate with each other.

The valve member 51 is composed of an umbrella valve. That is, the valve member 51 is formed in a substantially disc shape, and the shaft portion 511 formed at the center thereof is mounted in the center hole of the wall portion 53 so as to be disposed in the internal passage 523. The peripheral edge portion 512 of the valve member 51 is in elastic contact with the valve seat 532 formed on the surface of the wall portion 53 facing the second end portion 522, and the first end from the second end portion 522 side. The flow of the fluid to the part 521 side is blocked. That is, the valve member 51 functions as a backflow prevention valve.

On the other hand, the valve member 51 opens the valve at a predetermined pressure or higher with respect to the forward fluid flow from the first end portion 521 side to the second end portion 522 side. Allow. In this case, as shown in FIG. 4, the valve member 51 is separated from the valve seat 532 by the elastic deformation of the peripheral portion 512 toward the second end portion 522, and the shutoff state of the internal passage 523 by the valve member 51 is released. Is done. Under a fluid pressure lower than the predetermined pressure, the peripheral edge 512 is seated on the valve seat 532, and the shut-off state of the internal passage 523 is maintained.

For the valve member 51, a rubber material having resistance to various process gases is used. For example, when methane, propane, or the like is used as the process gas, it is resistant to hydrocarbon gases such as nitrile rubber (NBR), hydrogenated nitrile rubber (HNBR), and fluoro rubber (FKM). A rubber material having the following is used for the valve member 51. The thickness and size of the valve member 51 are not particularly limited, and are individually set to thicknesses and sizes that can ensure valve opening pressure that can meet various specifications.

That is, the valve opening pressure of the valve member 51 (minimum pressure necessary for opening the valve member 51) is set to a pressure that is at least higher than the valve opening pressure (first pressure) of the discharge valve 42. And the valve member 51 restrict | limits the gas flow below a predetermined pressure (2nd pressure) higher than the valve opening pressure.

The valve opening pressure of the valve member 51 is determined with reference to the gas pressure P1 supplied from the pressure source 2 of the pump system 1. In the present embodiment, the valve opening pressure of the valve member 51 is set to a pressure higher than the gas pressure P1 of the pressure source 2. Thereby, even if the gas pressure P1 of the pressure source 2 is larger than the valve opening pressure of the discharge valve 42, the outflow of gas from the discharge port 102 to the processing unit 4 when the operation of the pump device 3 is stopped is shut off. The outflow of gas to the processing unit 4 can be reliably prevented.

As will be described later, the valve opening pressure of the valve member may be set to a pressure lower than the gas pressure P2 of the pressure source 2.

[Operation of pump device]
Next, a typical operation example of the pump device 3 configured as described above will be described.

The pump device 3 is driven by starting the motor 21 of the drive unit 20. The number of rotations of the motor 21 is controlled by the control unit 5 so as to be a constant discharge flow rate based on, for example, a flow meter installed on the discharge side of the pump device 3. The motor 21 reciprocates the movable member 30 with a predetermined stroke in the operation space 105 by rotating the eccentric cam 35 via the rotating shaft 210. Thereby, the diaphragm 31 which divides the pump chamber 100 moves up and down, and the volume of the pump chamber 100 changes periodically.

The movable member 30 alternately changes the volume of the pump chamber 100 to alternately suck gas into the pump chamber 100 and discharge gas from the pump chamber 100. That is, fuel gas having a pressure P1 (for example, 2 kPa (gauge pressure)) is introduced into the pump chamber 100 from the pressure source 2 connected to the suction port 101 via the suction valve 41. The fuel gas introduced into the pump chamber 100 is pressurized by being compressed by the movable member in the pump chamber 100 to open the discharge valve 42 and the valve mechanism 50. By repeating the above operation, a fuel gas having a pressure P2 (for example, 15 kPa (gauge pressure)) is discharged from the discharge port 102 to the processing unit 4.

Here, the discharge valve 42 opens when the pressure in the pump chamber 100 reaches or exceeds the valve opening pressure of the discharge valve 42, and allows the gas flow from the pump chamber 100 to the discharge port 102. Accordingly, when gas is introduced into the pump chamber 100 from the suction port 101 at a pressure equal to or higher than the opening pressure of the discharge valve 42 when the pump device 3 is stopped, the flow of gas toward the discharge port 102 by opening the discharge valve 42. Will be formed.

Therefore, in the pump device 3 of this embodiment, the valve mechanism 50 is attached to the discharge port 102. The valve mechanism 50 has a valve opening pressure higher than the gas pressure (P1) of the pressure source 2. Accordingly, even when the gas having the pressure P1 is introduced from the suction port 101 to the pump chamber 100 when the pump device 3 is stopped, the gas flow is blocked by the valve mechanism 50, and the gas flow from the discharge port 102 to the processing unit 4 is prevented. Outflow is prevented. In this way, inadvertent discharge of gas when the operation is stopped is suppressed, so that the possibility of problems occurring in the system can be solved.

In the present embodiment, the valve mechanism 50 has a structure capable of continuously changing the opening according to the introduction pressure. As a result, the valve mechanism 50 can be opened according to the discharge pressure when the operation of the pump device 6 is resumed, and a necessary flow rate of gas can be quickly supplied to the processing unit 4.

FIG. 5 shows the change over time in the discharge flow rate of the pump device 3 when the operation and stop of the pump device 3 are repeated under the experimental conditions shown in FIG. In FIG. 6, a is a buffer tank, b is a pressure gauge, c is a suction pipe, and d is a blower, which corresponds to the pump device 3 of this embodiment. e is a pressure gauge, f is a discharge pipe, g is a fixed orifice, and h is a flow meter.

As shown in FIG. 5, the minimum value of the discharge flow rate was 0, and it was confirmed that the gas closing function by the valve mechanism 50 was functioning normally when the operation of the pump device 3 was stopped. It was also confirmed that the discharge flow rate of the pump device 6 was stably maintained at a constant value and the reproducibility was high.

FIG. 7 shows an experimental result showing a change in the discharge flow rate of the pump device 6 with respect to the rotation speed control voltage (Vsp) input to the motor 21 of the pump device 6. The piping system in which the pump device 6 was incorporated was the same as the piping example shown in FIG.

As shown in FIG. 7, after starting the operation of the pump device, gas discharge is started when a predetermined number of revolutions is reached, and it is confirmed that the flow rate increases almost in proportion to the driving number of revolutions of the pump device. It was. Thus, according to this embodiment, a gas closing function and stable discharge flow rate control can be realized.

<Second Embodiment>
FIG. 8 shows a pump device according to a second embodiment of the present invention. Hereinafter, configurations different from those of the first embodiment will be mainly described, and configurations similar to those of the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted or simplified.

The pump device 6 of the present embodiment is different from the first embodiment described above in the configuration of the valve mechanism 60 attached to the discharge port 102. The valve mechanism 60 has a valve member 61 that constitutes an umbrella valve, and is installed in the internal passage of the housing 62 in the same form as the first embodiment shown in FIGS. 3 and 4.

The valve mechanism 60 of the present embodiment has a function of restricting the outflow of gas that is equal to or higher than the valve opening pressure (first pressure) of the discharge valve 42 and equal to or lower than the gas pressure P1 (second pressure) of the pressure source 2. This is common to the first embodiment. However, the valve mechanism 60 in the present embodiment allows the outflow of gas from the discharge port 102 to the processing unit 4 when the operation of the pump device 6 is stopped, but has a function of suppressing the outflow amount to a predetermined value or less. Different from the first embodiment.

That is, the valve opening pressure of the valve member 61 of the present embodiment is set to a pressure lower than the gas pressure P1 of the pressure source 2. Since the valve mechanism 60 of the present embodiment has a structure capable of continuously changing the opening degree according to the gas pressure, the gas flowing out to the processing unit 4 side according to the gas pressure introduced into the valve mechanism 60. It is possible to control the flow rate.

In this case, the pressure required to fully open the valve member 61 is set to a pressure higher than the gas pressure P1 of the pressure source 2 (for example, a discharge pressure (P2) or less during normal operation of the pump device 3). As a result, the valve mechanism 60 can control the flow rate of the gas not less than the valve opening pressure (first pressure) of the discharge valve 42 and not more than the gas pressure P1 (second pressure) of the pressure source 2.

According to the present embodiment, when the operation of the pump device 6 is stopped, the gas flow rate supplied from the pressure source 2 can be reduced to a predetermined flow rate and supplied to the processing unit 4. As a result, it is not necessary to separately provide a throttle valve such as an orifice on the upstream side or the downstream side of the pump device 6, and the number of system components can be reduced. This embodiment is suitably used for a system that needs to supply a gas having a predetermined flow rate or less to the processing unit 4 even when the operation of the pump device 6 is stopped.

<Third Embodiment>
FIG. 9 shows a pump device according to a third embodiment of the present invention. Hereinafter, configurations different from those of the first embodiment will be mainly described, and configurations similar to those of the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted or simplified.

The pump device 7 of the present embodiment has a casing 70 including a pump body 11, a pump head 72, and a pump head cover 73. The pump head 72 is formed with a suction port 101 and a discharge port 102, respectively. The valve mechanism 50 described in the first embodiment is attached to the discharge port 102.

The pump head 72 is formed with a suction passage T1, a discharge passage T2, and a buffer tank 721, respectively. At least a part of these passages is exposed to the outside from the upper surface of the pump head 72, and is shielded from the outside air by being covered with a pump head cover 73 via a seal member.

Generally, diaphragm pumps structurally generate pulsation in the discharge gas. When the pump rotation speed is controlled based on the measured value of the flow rate of the discharge gas, if the pulsation is large, the accurate flow rate cannot be measured, and the pump drive control becomes unstable. Further, when the discharge gas is a fuel gas, the pulsation may cause unstable combustion or incomplete combustion.

Therefore, the pump device 7 of the present embodiment has a buffer tank 721 between the discharge passage T2 and the discharge port 102. The buffer tank 721 forms a space 74 between the discharge valve 42 (discharge passage T <b> 2) and the valve mechanism 50 in which a part of the flow path connecting these is expanded. The buffer tank 721 has a function of buffering the pulsation of the gas discharged from the discharge valve 42.

According to the pump device 7 of the present embodiment, the pulsation of the gas discharged from the valve mechanism 50 can be reduced, and the gas can be discharged at a stable flow rate. Further, when the drive of the pump device 7 is controlled based on the discharge flow rate, stable drive control of the pump device 7 is possible. Furthermore, since the pump and the buffer tank are integrated, there is no need to provide a separate buffer tank in the gas flow path of the pump system, and the system configuration can be simplified.

The volume of the space 74 of the buffer tank 721 is determined based on the pulsation (pressure width) of the gas discharged from the discharge valve 42. FIG. 10 shows a result of an experiment conducted by the present inventors and shows a relationship between the buffer volume (cc) and the pressure width of the gas discharged from the discharge port 102. As shown in FIG. 10, the larger the volume of the space 74, the smaller the pressure width. For example, the pulsation width can be suppressed to 0.75 kPa or less by setting the volume of the space 74 to 120 cc or more.

<Fourth Embodiment>
FIG. 10 shows a pump device according to a fourth embodiment of the present invention. Hereinafter, configurations different from those of the first embodiment will be mainly described, and configurations similar to those of the above-described embodiment will be denoted by the same reference numerals, and description thereof will be omitted or simplified.

The pump device 8 of the present embodiment includes a casing 80, a drive unit 20, and a buffer tank 81. The casing 80 has a suction port 101 and a discharge port 102, pressurizes the gas sucked from the suction port 101 in a pump chamber (not shown), and discharges the boosted gas from the discharge port 102 via the buffer tank 81. To do.

FIG. 11 is a cross-sectional view of the buffer tank 81 and the discharge port 102. A space 74 having a predetermined volume is formed inside the buffer tank 81 to reduce pulsation of the discharge gas. The discharge port 102 communicates with the space 74, and a valve member 51 is attached inside the discharge port 102. The valve member 51 has the same configuration as that of the first embodiment, and has a function of restricting the outflow of gas having a predetermined pressure or less.

Also in the present embodiment configured as described above, the same operational effects as those of the above-described embodiments can be obtained. According to the pump device 8 of the present embodiment, since the valve member 51 as the valve mechanism is supported by the casing 80, the number of parts can be reduced.

13 to 18 show the appearance of the pump device 8. FIG. 13 is a front view, FIG. 14 is a rear view, FIG. 15 is a plan view, FIG. 16 is a bottom view, FIG. Is a left side view.

As mentioned above, although embodiment of this invention was described, this invention is not limited only to the above-mentioned embodiment, Of course, in the range which does not deviate from the summary of this invention, a various change can be added.

For example, in the above embodiment, the valve mechanism that restricts the flow of fluid below a predetermined pressure is attached to the discharge port. However, the present invention is not limited to this. It may be provided.

Further, the valve member constituting the valve mechanism is not limited to the umbrella valve, and may be constituted by, for example, a ball valve or a butterfly valve.

In the above embodiment, the pump device is a diaphragm pump. However, the present invention is not limited to this, and the present invention can also be applied to other pump devices such as a roots pump. In the case of a roots pump, the movable member that changes the volume of the pump chamber corresponds to rotors that are arranged to face each other.

DESCRIPTION OF SYMBOLS 1 ... Pump system 2 ... Pressure

source

3, 6, 7, 8 ... Pump apparatus 4 ... Processing

part

10, 70, 80 ... Casing 20 ... Drive part 30 ... Movable member 31 ... Diaphragm 41 ... Suction valve 42 ... Discharge valve 50, DESCRIPTION OF SYMBOLS 60 ...

Valve mechanism

51, 61 ... Valve member 74 ... Space part 100 ... Pump chamber 101 ... Inlet port 102 ... Discharge port

Claims

A casing having a suction port, a discharge port, and a pump chamber capable of communicating with each of the suction port and the discharge port;
A movable member that is movable inside the casing and alternately sucks fluid into the pump chamber and discharges the fluid from the pump chamber;
A first valve attached between the suction port and the pump chamber and allowing the fluid to flow from the suction port to the pump chamber;
A second valve attached between the pump chamber and the discharge port and allowing the fluid to flow from the pump chamber to the discharge port when the fluid in the pump chamber is at or above a first pressure; ,
The flow of fluid from the suction port toward the discharge port when the fluid between the suction port and the discharge port is not more than a second pressure greater than the first pressure is attached to the casing. And a third valve for limiting.
The pump device according to claim 1,
The third valve is disposed closer to the discharge port than the second valve.
The pump device according to claim 2,
The third valve includes a valve member whose opening degree changes continuously in accordance with a pressure not lower than the first pressure and not higher than the second pressure.
The pump device according to claim 3,
The valve member is an umbrella valve.
The pump device according to claim 2,
The casing further includes a space portion in which a part of a flow path communicating between the second valve and the third valve is expanded.
The pump device according to claim 1,
The movable member is
A pump device comprising a deformable diaphragm that partitions the pump chamber.
A casing having a suction port communicating with the pressure source, a discharge port communicating with the processing section, and a pump chamber capable of communicating with the suction port and the discharge port,
A movable member that is movable in the casing and alternately sucks the fluid into the pump chamber and discharges the fluid from the pump chamber;
A first valve attached between the suction port and the pump chamber and allowing the flow of the fluid from the suction port toward the pump chamber;
A second valve attached between the pump chamber and the discharge port and allowing the flow of the fluid at a pressure equal to or higher than a first pressure toward the discharge port from the pump chamber;
A pump device, which is attached to the casing and has a third valve for restricting the flow of the fluid below the second pressure that is greater than the first pressure and that is directed from the suction port to the discharge port;
A pressure source connected to the suction port for supplying fluid below the second pressure to the pump device;
A pump system comprising: a processing unit that is connected to the discharge port and processes fluid discharged from the pump device.
The pump system according to claim 7,
The third valve includes a valve member that blocks the flow of the fluid below the second pressure.
The pump system according to claim 7,
The third valve includes a valve member whose opening degree continuously changes in accordance with a pressure not lower than the first pressure and not higher than the second pressure.