Diaphragm Pump

Description

CROSS-REFERENCING OF RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2022-43973, which is incorporated by reference into the description of this application.

FIELD OF THE INVENTION

The present invention relates to a diaphragm pump for suctioning and ejecting a target liquid.

BACKGROUND OF THE INVENTION

The above diaphragm pump includes a diaphragm that defines a pumping chamber (pump chamber) and a working chamber (hydraulic oil chamber). In the diaphragm pump, the diaphragm is operated by a pressurizing plunger that slides in a cylinder body of a liquid cylinder connected to the working chamber.

When the pressurizing plunger is in a backward stroke, the pumping chamber side is depressurized. As a result, the diaphragm deforms toward the working chamber, which is the backward stroke side. This causes the target liquid to be delivered to be sucked into the pumping chamber through a suction port.

The forward stroke of the pressurizing plunger after the target liquid is suctioned into the pumping chamber causes the working chamber side to be pressurized. Accordingly, the diaphragm deforms toward the pumping chamber, which is the forward stroke side. This allows the suctioned target liquid to be ejected from the pumping chamber through an ejecting port (see, for example, Patent Document 1).

Meanwhile, diaphragms may be broken due to product defects or deterioration over time. If the diaphragm is broken, hydraulic oil in the working chamber is mixed into the target liquid, resulting in contamination of the target liquid.

When the pressure of the working chamber becomes negative due to the backward stroke of the pressurizing plunger, air dissolved in hydraulic liquid in the working chamber may expand and be bubbled. In this situation, as the pressurizing plunger reciprocates, bubbles in the working chamber expand and contract, so that the pressure of hydraulic liquid is not fully transmitted to the diaphragm, resulting in poor performance in pumping the target liquid.

CITATION LIST

Patent Literature

[Patent Literature 1] JP 2002-70747 A (See FIG. 1)

SUMMARY

Technical Problem

In view of the above, an object of the present invention is to provide a diaphragm pump that can avoid the risk of contamination of the target liquid due to the breakage of the diaphragm, while at the same time ensuring pumping performance.

Solution to Problem

The diaphragm pump of the present invention includes a pump part that pumps the target liquid by suctioning and delivering the target liquid, and a drive part that drives the pump part to pump the target liquid. The pump part includes a pumping chamber that includes a suction part that suctions the target liquid and an ejecting part that ejects the suctioned target liquid, a working chamber that is filled with hydraulic liquid, an intermediate chamber that is located between the pumping chamber and the working chamber and that is filled with intermediate liquid, a liquid contact diaphragm that seals between the pumping chamber and the intermediate chamber, a working diaphragm that seals between the intermediate chamber and the working chamber, and a working mechanism that is configured to cause the liquid contact diaphragm and the working diaphragm to deform in one direction when the target liquid is suctioned, and to deform in an other direction opposite to the one direction when the target liquid is ejected, so as to change the volume of each of the pumping chamber, the working chamber, and the intermediate chamber. The working mechanism includes a working part that is connected to the working diaphragm and configured to reciprocate in the one direction and the other direction by the driving of the drive part, a coupling part that couples the liquid contact diaphragm and the working diaphragm, and a biasing part that biases at least one of the liquid contact diaphragm and the working diaphragm toward the one direction side.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a front view of a diaphragm pump.

FIG. 2 is a longitudinal cross-sectional front view of the diaphragm pump.

FIG. 3 is a partially omitted longitudinal cross-sectional side view of the diaphragm pump.

FIG. 4 is a longitudinal cross-sectional front view of a drive part of the diaphragm pump.

FIG. 5 is a transverse cross-sectional plan view of the drive part of the diaphragm pump.

FIG. 6 is a longitudinal cross-sectional view of a main part of the diaphragm pump.

FIG. 7 is an enlarged view showing operations of a liquid contact diaphragm and a working diaphragm.

FIG. 8 is a graph showing the pressures in three chambers relative to the time under normal conditions.

FIG. 9 is a graph showing the pressures in three chambers relative to the time when the working diaphragm is broken.

FIG. 10 is a graph showing the pressures in three chambers relative to the time when the liquid contact diaphragm is broken.

FIG. 11 is a block diagram for detecting breakage of the liquid contact diaphragm or the working diaphragm.

DESCRIPTION OF EMBODIMENTS

A description will be hereinbelow given on a hydraulic diaphragm pump with reference to the drawings.

FIG. 1 is a front view of a diaphragm pump. FIG. 2 is a longitudinal cross-sectional front view of the diaphragm pump. FIG. 3 is a partially omitted longitudinal cross-sectional side view of the diaphragm pump.

The diaphragm pump includes two pump parts 1 that pump a liquid (hereinafter referred to as “target liquid”) by suctioning and ejecting the target liquid, and a drive part 2 (see FIG. 4) that drives the pump parts 1 to pump the target liquid. Although this diaphragm pump includes two parts 1 to prevent pulsation, it can include one pump part 1 only.

As shown in FIG. 2, one (left side) pump part 1 and the other (left side) pump part 1 each include a pumping chamber 5 that includes a suction part 3 (see FIG. 3) to suction the target liquid and an ejecting part 4 (see FIG. 3) to eject the suctioned target liquid, a working chamber 6 that is filled with hydraulic liquid, an intermediate chamber 7 that is located between the pumping chamber 5 and the working chamber 6 and that is filled with an intermediate liquid, a liquid contact diaphragm 8 that is configured to close (seal) between the pumping chamber 5 and the intermediate chamber 7 and that has a circular outer shape, and a working diaphragm 9 that is configured to close (seal) between the intermediate chamber 7 and the working chamber 6 and that has a circular outer shape, and a working mechanism 10 that is configured to cause the liquid contact diaphragm 8 and the working diaphragm 9 to deform in one direction when the target liquid is suctioned, and to deform in an other direction opposite to the one direction when the target liquid is ejected, so that the volume of each of the pumping chamber 5, the working chamber 6, and the intermediate chamber 7 is changed.

One (left side) pump part 1 and the other (right side) pump part 1 have the same configuration, but the timing at which one (left side) pump part 1 ejects the target liquid and the timing at which the other (right side) pump part 1 ejects the target liquid are different from each other.

As shown in FIG. 3, the suction part 3 has a suction conduit 31 through which the target

liquid passes toward the pumping chamber 5, two suction paths 32 and 33 in communication with the suction conduit 31, and two suction-side check valves 34 and 35, respectively connected to the separate suction paths 32 and 33.

In the suction part 3 of this embodiment, the path through which the target liquid flows is branched into one suction path 32 and the other suction path 33.

Of the two suction-side check valves 34 and 35, the one suction-side check valve 34 is connected to an internal path P3a that communicates with the pumping chamber 5 of the one pump head 1.

Of the two suction-side check valves 34 and 35, the other suction-side check valve 35 is connected to an internal path P3b that communicates with the pumping chamber 5 of the other pump head 1.

The ejecting part 4 includes two discharge-side check valves 41 and 42 through which the target liquid fed from the pumping chamber 5 passes, and an ejecting conduit 43 with which the two discharge-side check valves 41 and 42 communicate.

Of the two discharge-side check valves 41 and 42, one discharge-side check valve 41 is connected to an internal path P4a that communicates with the pumping chamber 5 of the one pump head 1.

Of the two discharge-side check valves 41 and 42, the other discharge-side check valve 42 is connected to an internal path P4b that communicates with the pumping chamber 5 of the other pump head 1.

Therefore, in the ejecting part 4 of this embodiment, the paths through which the target liquid flows merge at the ejecting conduit 43.

Although not shown in the Figures, a supply pipe is connected to the suction conduit 31 to supply the liquid, and a transfer pipe is connected to the ejecting conduit 43 to receive and transfer the liquid to be ejected to a predetermined position.

The pumping chamber 5 is a chamber (space) through which the target liquid to be sent from the suction part 3 to the ejecting part 4 passes, as shown in FIG. 2.

The working chamber 6 is isolated from the intermediate chamber 7 by the working diaphragm 9. The working chamber 6 is a chamber (space) where hydraulic liquid is supplied to reciprocate the working diaphragm 9 (hydraulic liquid (hydraulic oil) to deform the working diaphragm 9 toward the intermediate chamber 7, which is the forward stroke side).

The intermediate chamber 7 is isolated from the pumping chamber 5 by the liquid contact diaphragm 8 and from the working chamber 6 by the working diaphragm 9. In other words, the intermediate chamber 7 is a chamber (liquid-filled chamber) formed between the liquid contact diaphragm 8 and the working diaphragm 9.

The intermediate chamber 7 is filled with liquid (hereinafter referred to as intermediate liquid).

If hydraulic liquid leaks from the working chamber 6 due to breakage of the working diaphragm 9, hydraulic liquid leaking from the working chamber 6 enters the intermediate chamber 7. Therefore, the pump part 1 in this embodiment is configured to prevent hydraulic liquid leaking from the working chamber 6 from reaching the pumping chamber 5.

Thus, the intermediate chamber 7 is formed to prevent hydraulic liquid from moving to the pumping chamber 5.

Intermediate liquid can be the same kind of liquid as the target liquid to be transferred, or it can be a different kind of liquid from the target liquid. However, if intermediate liquid is a different kind of liquid from the target liquid, intermediate liquid should be a liquid that does not contaminate the target liquid (i.e., does not change the properties of the target liquid) even if it gets mixed into the target liquid as a result of breakage of the liquid contact diaphragm 8.

As shown in FIG. 6, a first screw 14 protruding toward the working chamber 6 is attached to a center portion of the liquid contact diaphragm 8 (a center portion of the liquid contact diaphragm 8 in the plane direction).

A second screw 15 protruding toward the pumping chamber 5 and a third screw 16 protruding toward the working chamber 6 are attached to a center portion of the working diaphragm 9 (a center portion of the working diaphragm 9 in the plane direction).

The working mechanism 10 has a bar-shaped rod 11, which is a working part that reciprocates in one direction and in the other direction while connected to the working diaphragm 9, a coupling part 12 that couples the liquid contact diaphragm 8 and the working diaphragm 9, and a tensile coil spring 13 as a biasing part that biases the working diaphragm 9 toward the suction side (backward stroke side and the one direction side) in the reciprocating motion. In addition to the tensile coil spring 13, the biasing part can be formed of a plate spring, an elastic body, or the like.

The rod 11 is configured to be driven (reciprocate) by the driving force of the drive part 2 (see FIG. 4). The direction in which the rod 11 reciprocates and the direction in which the liquid contact diaphragm 8 and the working diaphragm 9 deform are the same direction.

An end portion of the rod 11 is coupled to the third screw 16. A connection part 11A with a threaded hole 11a formed therein is fixed to the end portion of the rod 11 of this embodiment. The third screw 16 is screwed into the threaded hole 11a of the connection part 11A.

The coupling part 12 is located within the intermediate chamber 7. The coupling part 12 is configured to couple the liquid contact diaphragm 8 and the working diaphragm 9, as described above.

More specifically, the coupling part 12 has a cylindrical shape. A threaded hole 12A is formed at one end of the coupling part 12 in the axial direction. A threaded hole 12B is also formed at the other end of the coupling part 12 in the axial direction.

A first screw 14 protruding from a center portion of the liquid contact diaphragm 8 (a center portion of the liquid contact diaphragm 8 in the plane direction) toward the working chamber 6 is screwed into the threaded hole 12A at one end of the coupling part 12. A second screw 15 protruding from a center portion of the working diaphragm 9 (a center portion of the working diaphragm 9 in the plane direction) toward the pumping chamber 5 is screwed into the threaded hole 12B at the other end of the coupling part 12. Therefore, the center portion of the liquid contact diaphragm 8 and the center portion of the working diaphragm 9 are coupled by the coupling part 12.

Thus, the coupling part 12 in this embodiment is a nut member with a female thread formed at each of one end and the other end in the axial direction.

In this configuration of the pump part 1 of this embodiment, when the rod 11 moves toward one side in the axial direction (toward the pumping chamber 5), the liquid contact diaphragm 8 and the working diaphragm 9 move toward the pumping chamber 5. When the rod 11 moves toward the other side in the axial direction (toward the working chamber 6), the liquid contact diaphragm 8 and the working diaphragm 9 move toward the working chamber 6. In the following description, the movement of the liquid contact diaphragm 8 and the

working diaphragm 9 toward the pumping chamber 5 is referred to as forward stroke, and the movement toward the working chamber 6 is referred to as backward stroke.

Here, the working mechanism 10 of this embodiment has a safety valve 17 attached to the rod 11. The safety valve 17 is located in a hydraulic liquid restriction chamber 18 that communicates with the working chamber 6. A valve seat 19 is formed on the inner surface of the hydraulic liquid restriction chamber 18, which receives (is in contact with) the safety valve 17.

Furthermore, the working mechanism 10 of this embodiment includes a gas discharge mechanism 20 to properly discharge gas (e.g., air) mixed into hydraulic liquid (hydraulic oil) in the working chamber 6 and the hydraulic liquid restriction chamber 18.

As shown in FIG. 5, the drive part 2 includes a tank 21, which is a reservoir that stores hydraulic liquid to be supplied to the working chambers 6, a driving force supply part 22 that supplies hydraulic liquid in the tank 21 to the working chambers 6 at an appropriate timing to reciprocate the liquid contact diaphragms 8 and the working diaphragms 9, an electric motor 24 that drives an eccentric cam 23 that makes up the driving force supply part 22, and a gear part 26 for transmitting the rotational force from the electric motor 24 to a driving force transmission shaft 25.

The driving force supply part 22 includes the driving force transmission shaft 25 to which the rotational force from the aforementioned electric motor 24 is transmitted, the eccentric cam 23 attached to the driving force transmission shaft 25, a pair of pistons 27 and 28 that reciprocate in response to the movement of the eccentric cam 23, a first rotating shaft 36 supported by inner rings of bearings 29 within one of the pair of pistons (first piston) 27, a second rotating shaft 37 supported by inner rings of bearings 30 in the other piston (second piston) 28, a coil spring (not shown) as a biasing device that is located within the second piston 28 to function to appropriately bias the first piston 27 and the second piston 28 to bring the respective rotating shafts 36 and 37 in the first piston 27 and the second piston 28 into contact with the eccentric cam 23, and a casing 21, which is the tank 21 that encloses these elements.

In the driving force supply part 22, a sealed space generated between the inner wall of the casing 21 and the pistons 27 and 28 is filled with hydraulic liquid. The reciprocating motion of the pistons 27 and 28 can produce a state in which hydraulic liquid (hydraulic oil) in the tank 21 is supplied to the working chambers 6 (see FIG. 2) (supply state) and a state in which hydraulic liquid is returned to the tank 21 side (return state).

Lids 38 and 39 are provided at the left and right ends of the casing 21. The lids 38 and 39 are connected to pipe members 40 and 41 through which hydraulic liquid to be supplied to the working chambers 6 and 6 passes.

Hydraulic liquid in the tank (casing) 21 is filled in a space formed between the ends of the pistons 27 and 28 and the working diaphragms 9 (see FIG. 2) via the piping members 40 and 41.

Accordingly, hydraulic liquid in the tank 21 is pressurized or depressurized according to the movement of the pistons 27 and 28, and thereby hydraulic liquid is distributed through the pipping members 40 and 41. As a result, when the working diaphragms 9 reciprocate, the working diaphragms 9 and the liquid contact diaphragms 8 coupled to the working diaphragms 9 reciprocate in the same manner.

Next, the description will be given for the operation of suctioning and pumping out the target liquid by a fixed amount using the diaphragm pump configured as described above.

First, when the electric motor 24 is driven, the driving force of the electric motor 24 is transmitted to the driving force transmission shaft 25. The eccentric cam 23 then rotates. When the eccentric cam 23 rotates, the first piston 27 and the second piston reciprocate.

When the first piston 27 moves toward the forward stroke side, the path communicating with the tank 21 and the working chamber 6 of one of the working diaphragms 9 is pressurized. At this time, the second piston 28 moves toward the backward stroke side, and the path communicating with the tank 21 and the working chamber 6 of the other working diaphragm 9 is depressurized.

This allows hydraulic liquid (hydraulic oil) in tank 21 to be supplied to the working chamber 6 of the one working diaphragm 9 and hydraulic liquid (hydraulic oil) in the working chamber 6 of the other working diaphragm 9 to be supplied (returned) to tank 21. When the first piston 27 moves toward the backward stroke side and the aforementioned path is depressurized, hydraulic liquid (hydraulic oil) in the working chamber 6 of the one the working diaphragm 9 returns to tank 21.

As a result, the one working diaphragm 9 deforms from the position shown by the two-dot chain line in FIG. 7 toward the working chamber 6 as shown by the solid line in FIG. 7, due to the biasing force of the biasing part 13. As a result, the working diaphragm 9 and the liquid contact diaphragm 8 coupled to the working diaphragm 9 deform in the same manner toward the working chamber 6 (from the position shown by the two-dot chain line in FIG. 7 to the position shown by the solid line in FIG. 7), the suction-side check valves 34 and 35 are opened while the eject-side check valves 41 and 42 are closed, and the target liquid is sucked (taken) into the pumping chamber 5 by an amount by which the liquid contact diaphragm 8 has deformed.

When the first piston 27 then moves from the backward stroke side to the forward stroke side, the path communicating with the tank 21 and the working chamber 6 of the one of the working diaphragms 9 is pressurized. One of the working diaphragms 9 deforms from the working chamber 6 side toward the pumping chamber 5 side against the biasing force of the biasing part 13 so that the one of the working diaphragms 9 is moved from the position shown by the solid line in FIG. 7 to the position shown by the two-dot chain line.

When the working diaphragm 9 and the liquid contact diaphragm 8 coupled to the working diaphragm 9 are thereby deformed in the same manner toward the pumping chamber 5 (deformed from the position shown by the solid line to the position shown by the two-dot chain line in FIG. 7), the eject-side check valves 41 and 42 are opened while the suction-side check valves 34 and 35 are closed, so that the target liquid is ejected and transferred (sent) to a predetermined location.

The biasing part 13 biases the liquid contact diaphragm 9 to make the pressure in the pumping chamber 5 smaller than the pressure in the intermediate chamber 7 and the pressure in the working chamber 6, and make the pressure in the intermediate chamber 7 smaller than the pressure in the working chamber 6 so as to maintain the relationship of the pressure in the pumping chamber 5<the pressure in the intermediate chamber 7<the pressure in the working chamber. Thereby, the application of the biasing force of the biasing part 13 to the intermediate chamber 7 and the working chamber 6 causes the intermediate chamber 7 and the working chamber 6 to be pressurized, which makes the pressure in the intermediate chamber 7 and the pressure in the working chamber 6 higher than the pressure in the pumping chamber 5.

The pressure in the working chamber 6 becomes higher than the pressure in the intermediate chamber 7 because the working chamber 6 is applied with the tension of the working diaphragm 9. The relationship between these pressures is shown in FIG. 8, in which the pressure in the working chamber 6 is shown by the dotted line 44, the pressure in the intermediate chamber 7 by the solid line 45, and the pressure in the pumping chamber 5 by the two-dot chain line 46 on the vertical axis with the three chambers against time on the horizontal axis.

When the working chamber 6 is applied with the tension of the working diaphragm 9, the pressure close to the maximum value of the working chamber 6 becomes slightly higher than the pressure close to the maximum value of the intermediate chamber 7.

Depending on the pressure in the working chamber 6 or the pressure in the intermediate chamber 7, the liquid contact diaphragm 8 or the working diaphragm 9 may be broken. Therefore, it is preferable that the diaphragm pump be used with a breakage detection device 50 that detects breakage of at least one of the liquid contact diaphragm 8 and the working diaphragm 9. The breakage detection device 50 can be incorporated into the diaphragm pump. The breakage detection device 50 can be a separate device from the diaphragm pump or can be a device connected to the diaphragm pump.

The breakage detection device 50 is configured to detect breakage of at least one of the liquid contact diaphragm 8 and the working diaphragm 9 based on at least one of the pressure in the pumping chamber 5, the pressure in the intermediate chamber 7, and the pressure in the working chamber 6.

Specifically, as shown in FIG. 11, the breakage detection device 50 includes a first pressure sensor 47 that detects the pressure of the pumping chamber 5, a second pressure sensor 48 that detects the pressure of the intermediate chamber 7, and a third pressure sensor 49 that detects the pressure of the working chamber 6, and is configured to detect the breakage of at least one of the liquid contact diaphragm 8 and the working diaphragm 9 based on the pressure of the intermediate chamber 7 detected through at least the second pressure sensor 48 out of the first pressure sensor 47, the second pressure sensor 48, and the third pressure sensor 49.

The graph in FIG. 9 shows the pressure in the pumping chamber 5, the pressure in the working chamber 6, and the pressure in the intermediate chamber 7 when the working diaphragm 9 is broken. In the graph in FIG. 9, the pressure in the working chamber 6 is shown by a dotted line 44, the pressure in the intermediate chamber 7 by a solid line 45, and the pressure in the pumping chamber 5 by a two-dot chain line 46.

In the conditions shown by the graph in FIG. 9, when the working diaphragm 9 is broken, the intermediate chamber 7 and the working chamber 6 become communicate with each other (not partitioned), so the difference between the pressure close to the maximum value of the working chamber 6 and the pressure close to the maximum value of the intermediate chamber 7 becomes small (i.e., the pressure close to the maximum value of the working chamber 6 and the pressure close to the maximum value of the intermediate chamber 7 become almost the same pressure).

In this case, the breakage detection device 50 is configured such that the pressure value detected through the second pressure sensor 48 is compared with the pressure value detected through the third pressure sensor 49, and when the difference between these pressure values (the difference between the pressure value close to the maximum value of the working chamber 6 and the pressure value close to the maximum value of the intermediate chamber 7) falls below a predetermined set value (a second threshold set to a value smaller than the difference between the pressure value close to the maximum value of the working chamber 6 and the pressure value close to the maximum value of the intermediate chamber 7 in the normal conditions without breakage of the working diaphragm 9, it is detected that the working diaphragm 9 is broken.

Thus, the breakage detection device 50 is configured to detect breakage of the working diaphragm 9 based on the pressure relationship between the pressure in the intermediate chamber 7 and the pressure in the working chamber 6.

The breakage detection device 50 can have a different configuration from that described above. For example, the breakage detection device 50 can be configured such that the pressure in the intermediate chamber 7 is compared with the pressure in the pumping chamber 5, and when the difference between these pressure values (actually, the difference between the pressure value close to the maximum value of the intermediate chamber 7 and the pressure value of the 15 pumping chamber 5 for the corresponding time) exceeds a predetermined set value (a first threshold set to a value smaller than the difference between the pressure value close to the maximum value of the intermediate chamber 7 and the pressure value of the pumping chamber 5 for the corresponding time in the normal conditions without breakage of the working diaphragm 9), it is detected that the working diaphragm 9 is not broken.

The first and second thresholds can be set to the same value or different values, but if the first and second thresholds are set to be the same value, the detection timings can be matched to each other even if the detection is made in either case. Thus, the breakage detection device 50 can have any configuration as long as it detects breakage of the working diaphragm 9 based on the pressure relationship between the pressure in the intermediate chamber 7 and the pressure in the pumping chamber 5.

The graph in FIG. 10 shows the pressure in the pumping chamber 5, the pressure in the working chamber 6, and the pressure in the intermediate chamber 7 when the liquid contact diaphragm 8 is broken. In the graph in FIG. 10, the pressure in the working chamber 6 is shown by a dotted line 44, the pressure in the intermediate chamber 7 by a solid line 45, and the pressure in the pumping chamber 5 by a two-dot chain line 46.

In the conditions shown by the graph in FIG. 10, when the liquid contact diaphragm 8 is broken, the intermediate chamber 7 and the pumping chamber 5 come into communication with each other (state of being not partitioned), so the difference between the pressure in the intermediate chamber 7 and the pressure in the pumping chamber 5 becomes small (the pressure in the intermediate chamber 7 and the pressure in the pumping chamber 5 become almost the same as each other).

In this case, the breakage detection device 50 is configured such that the pressure in the intermediate chamber 7 is compared with the pressure in the pumping chamber 5, the pressure value detected through the first pressure sensor 47 is compared with the pressure value detected through the second pressure sensor 48, and when the difference between these pressure values falls below a predetermined set value (a third threshold value set to a value smaller than the difference between the pressure value of the intermediate chamber 7 and the pressure value of the pumping chamber 5 when the liquid contact diaphragm 8 is in the normal state without breakage), the breakage detection device 50 detects that the liquid contact diaphragm 8 is broken.

Thus, the breakage detection device 50 detects breakage of the liquid contact diaphragm 8 based on the pressure relationship between the pressure in the intermediate chamber 7 and the pressure in the pumping chamber 5.

The breakage detection device 50 can still have a different configuration. For example, the breakage detection device 50 can be configured such that the pressure in the intermediate chamber 7 is compared with the pressure in the working chamber 6, and the pressure value detected through the second pressure sensor 48 is compared with the pressure value detected through the third pressure sensor 49, and when the difference between these pressure values becomes equal to or exceeds a predetermined set value (a fourth threshold set to a value smaller than the difference between the pressure value close to the maximum value in the intermediate chamber 7 and the pressure value close to the maximum value of the working chamber 6 when the liquid contact diaphragm 8 is in a normal state without breakage), the breakage detection device 50 detects that the liquid contact diaphragm 8 is broken.

Thus, the breakage detection device 50 can be configured to detect breakage of the liquid contact diaphragm 8 based on the pressure relationship between the pressure in the intermediate chamber 7 and the pressure in the working chamber 6.

The third and fourth thresholds can be set to be the same as each other or different from each other, but if the third and fourth thresholds are set to the same as each other, the detection timings can be matched to each other even if the detection is made in either case.

The breakage detection device 50 can be configured to detect the breakage of the liquid contact diaphragm 8 or the working diaphragm 9 by detecting fluctuations in the pressure value of the intermediate chamber 7 detected only through the second pressure sensor 48.

Since the pressure value of the intermediate chamber 7 drops when the liquid contact diaphragm 8 is broken, the breakage detection device 50 can be configured to detect breakage of the liquid contact diaphragm 8 based on the pressure value detected through the second pressure sensor 48, through which it is detected that the pressure of the intermediate chamber 7 drops to a set pressure value or more. Since the pressure value close to the maximum value of the intermediate chamber 7 increases when the working diaphragm 9 is broken, the breakage detection device 50 can be configured to detect breakage of the working diaphragm 9 based on the pressure value detected through the second pressure sensor 48, through which it is detected that the pressure of the intermediate chamber 7 has increased to a set pressure value or more.

The breakage detection device 50 can be configured to, upon detection of breakage of the liquid contact diaphragm 8 or the working diaphragm 9, activate an alarm device such as a buzzer, a lamp, or a sound device, or to display the fact that the liquid contact diaphragm 8 or the working diaphragm 9 is broken by means of an electronic bulletin board, a monitor, or another display device to notify the operator, etc. of the breakage.

It is also preferred that a forcibly stopping means be provided to stop operation of the diaphragm pump at the same time as the aforementioned notification is made.

The diaphragm pump is not limited to the aforementioned embodiment, and various modifications can be made without departing from the gist of the present invention.

In the above embodiment, the biasing part 13 that biases the working diaphragm 9 toward the suction side (one of the above mentioned sides) is provided, but a biasing part that biases the liquid contact diaphragm 9 toward the suction side (one of the above mentioned sides), or a biasing part that biases both the liquid contact diaphragm 8 and the working diaphragm 9 toward the suction side (one of the above mentioned sides) can be provided.

This disclosure includes the following contents.

(1)

A diaphragm pump including:

• • a pump part that pumps a target liquid by suctioning and ejecting, and a drive part that drives the pump part to pump the target liquid,
  • the pump part including:
    a pumping part that includes a suction part that suctions the target liquid, and an ejection part that ejects the suctioned target liquid,
  • a working chamber that is filled with hydraulic liquid,
  • an intermediate chamber that is located between the pumping chamber and the working chamber, and is that is filled with intermediate liquid,
  • a liquid contact diaphragm that is configured to close between the pumping chamber and the intermediate chamber,
  • a working diaphragm that is configured to close between the intermediate chamber and the working chamber, and
  • a working mechanism that is configured to cause the liquid contact diaphragm and the working diaphragm to deform in one direction when the target liquid is suctioned, and to deform in an other direction opposite to the one direction when the target liquid is ejected, so as to change the volume of each of the pumping chamber, the working chamber, and the intermediate chamber 7, in which
  • the working mechanism including a working part that is connected to the working diaphragm and configured to reciprocate in the one direction and the other direction by the driving of the drive part, a coupling part that couples the liquid contact diaphragm and the working diaphragm, and a biasing part that biases at least one of the liquid contact diaphragm and the working diaphragm toward the one direction side.

(2) The diaphragm pump as set forth in Item 1 above, in which the coupling part is located in the intermediate chamber and is configured to couple center portions of the liquid contact diaphragm and the working diaphragm.

(3) The diaphragm pump as set forth in Item (1) or (2) above, in which the biasing part is configured to bias at least one of the liquid contact diaphragm and the working diaphragm so as to make the pressure of the pumping chamber smaller than the pressure of the intermediate chamber and the pressure of the working chamber, and make the pressure of the intermediate chamber smaller than the pressure of the working chamber.

(4) The diaphragm pump as set forth in Item (1) above, further including a breakage detection device configured to detect breakage of at least one of the liquid contact diaphragm and the working diaphragm based on at least the pressure of the intermediate chamber out of the pressure of the pumping chamber, the pressure of the intermediate chamber, and the pressure of the working chamber.

(5) The diaphragm pump as set forth in Item (4) above, in which the breakage detection device is configured to detect breakage of the working diaphragm based on the pressure relationship between the pressure of the intermediate chamber and the pressure of the pumping chamber or the pressure of the working chamber.

(6) The diaphragm pump as set forth in Item (4) above, in which the breakage detection device is configured to detect breakage of the liquid contact diaphragm based on the pressure relationship between the pressure of the intermediate chamber and the pressure of the pumping chamber or the pressure of the working chamber.

According to the diaphragm pump of Item (1) above, in which the liquid contact diaphragm and the working diaphragm are coupled by the coupling part, and at least one of the liquid contact diaphragm and the working diaphragm is biased by the biasing part toward the suction side in the reciprocating direction, it is possible to allow the liquid contact diaphragm and the working diaphragm to reciprocate to change the volume of each of the chambers.

Since the working chamber and the intermediate chamber are pressurized by the biasing force of the biasing part, the pressures of the working chamber and intermediate chamber can be prevented from becoming negative even when the liquid contact diaphragm and working diaphragm are in a backward stroke. Therefore, air dissolved in hydraulic liquid in the working chamber can be prevented from expanding and being bubbled, thus ensuring pumping performance.

Since the diaphragm pump includes two diaphragms, namely the liquid contact diaphragm and the working diaphragm, even if the liquid contact diaphragm is broken and intermediate liquid in the intermediate chamber flows into the pumping chamber, the problem of contamination in the pumping chamber will not occur if intermediate liquid is a liquid that will not cause such a problem even in the case where it flows into the pumping chamber.

If the working diaphragm is broken, hydraulic oil flows only into the intermediate chamber, and the liquid contact diaphragm can prevent hydraulic oil from moving into the pumping chamber.

According to the diaphragm pump as set forth in Item (2) above, the liquid contact diaphragm and the working diaphragm each can smoothly deform from the center portion to the radially outer side by the configuration of coupling the center portions of the liquid contact diaphragm and the working diaphragm by the coupling part, as described above.

According to the diaphragm pump as set forth in Item (3) above, the reciprocating movement of the liquid contact diaphragm and the working diaphragm can be performed smoothly if the biasing of the biasing part is set to maintain the relationship of the pressure of the pumping chamber<the pressure of the intermediate chamber<the pressure of the working chamber, as described above.

According to the diaphragm pump as set forth in Item (4) above, the pressure of the intermediate chamber fluctuates when at least one of the liquid contact diaphragm and the working diaphragm is broken. Based on this pressure fluctuation, it is possible to detect that at least one of the liquid contact diaphragm and the working diaphragm has been broken.

According to the diaphragm pump as set forth in Item (5), when the working diaphragm is broken, the pressure of the intermediate chamber fluctuates, so that the breakage of the working diaphragm can be detected based on the pressure relationship between the pressure of the intermediate chamber and the pressure of the pumping chamber, or between the pressure of the intermediate chamber and the pressure of the working chamber.

According to the diaphragm pump as set forth in Item (6) above, when the liquid contact diaphragm is broken, the pressure of the intermediate chamber fluctuates, so that the breakage of the liquid contact diaphragm can be detected based on the relationship between the pressure of the intermediate chamber and the pressure of the pumping chamber, or the pressure of the intermediate chamber and the pressure of the working chamber.

REFERENCE SIGNS LIST

• • 1: Pump part
  • 2; Drive part
  • 3: Suction part
  • 4: Ejection part
  • 5: Pumping part
  • 6: Working chamber
  • 7: Intermediate chamber
  • 8: Liquid contact diaphragm
  • 9: Working diaphragm
  • 10: Working mechanism
  • 11: Rod (working part)
  • 11A: Connection part
  • 11a: Threaded hole
  • 12: Coupling part (nut member)
  • 12A,12B: Threaded hole
  • 13: Tensile coil spring (biasing part)
  • 14: First screw
  • 15: Second screw
  • 16: Third screw
  • 17: Safety valve
  • 18: Hydraulic liquid restriction chamber
  • 19: Valve seat
  • 20: Gas discharge mechanism
  • 21: Tank (casing)
  • 22: Driving force supply part
  • 23: Eccentric cam
  • 24: Electric motor
  • 25: Driving force transmission shaft
  • 26: Gear part
  • 27, 28: Piston
  • 29, 30: Bearing
  • 31: Suction conduit
  • 32, 33: Suction path
  • 34, 35: Suction-side check valve
  • 36, 37: Rotating shaft
  • 38, 39: Lid
  • 40, 41: Piping member
  • 41, 42: Discharge-side check valve
  • 41, 42: Eject-side check valve
  • 43: Ejecting conduit
  • 44: Dotted line
  • 45: Solid line
  • 46: Two-dot chain line
  • 46, 48, 49: Pressure sensor
  • 50: Breakage detection device