LIQUID SUPPLY DEVICE

Abstract

A liquid supply device causes a tubephragm 15 as a first flexible member to expand to inject a liquid into a pump chamber 16, and causes the tubephragm 15 to contract to discharge the liquid in the pump chamber 16 to an outside, the device including: a medium accommodation case 28 having a bellows 31 as a second flexible member, the bellows partitioning a medium accommodation chamber 32 communicating with a pump accommodation chamber 17 and an air chamber 33; a drive mechanism 27 provided with a rod 44a; an electric motor 46 as a drive member for causing the rod 44a to reciprocate axially; and a pressure adjustment mechanism 60 for reducing a pressure in the air chamber 33 when the bellows 31 is contracted to expand the tubephragm 15 via a liquid medium M.

Description

TECHNICAL FIELD

The present invention relates to a liquid supply device for supplying a liquid to a coated object.

BACKGROUND

Liquid supply devices are used in a technical field of semiconductor integrated circuit devices, liquid crystal panels, and the like for supplying a liquid such as a photoresist liquid to a coated object, and in manufacturing a secondary battery using an electrolyte, the liquid supply device is used to supply an electrolyte to an inside of a battery container.

As such a liquid supply device, Patent Document 1 discloses a liquid supply device including a pump case incorporating a tubephragm as a radially elastically deformable flexible member, and a bellows case incorporating a bellows as an axially expandable flexible member. A primary port of a pump chamber in a tubephragm is connected to a liquid tank and a secondary port of the pump chamber is connected to a liquid discharge portion. A liquid medium made of an incompressible liquid is filled in communication with a pump accommodation chamber in the pump case and a medium accommodation chamber in the bellows case. By expanding and contracting the bellows, the pump chamber expands and contracts via the liquid medium, and the liquid in the liquid tank is discharged from the liquid discharge portion.

Patent Document 1: Japanese Patent Application Laid-open No. 2012-162269

SUMMARY

Problems to be Solved by the Invention

As disclosed in Patent Document 1, in the liquid supply device having the tubephragm incorporated in the pump case and the bellows incorporated into the bellows case, and causing the tubephragm to perform a pumping operation a pumping operation via the liquid medium by extending and contracting operations of the bellows, the bellows is contracted when the liquid is sucked into the pump chamber in the tube. Consequently, the liquid medium in the pump accommodation chamber of the pump case is sucked into a medium accommodation chamber in the bellows case and the tubephragm is radially expanded. Meanwhile, when the liquid sucked into the pump chamber is discharged to the liquid discharge portion, the bellows is extended. Consequently, the liquid medium in the medium accommodation chamber in the bellows case is supplied into the pump accommodation chamber of the pump case, and the tubephragm is contracted. Thus, in the liquid supply device with two flexible members, the pump operation is performed by both flexible members.

By extending the bellows to contract the tubephragm via the liquid medium, a positive pressure is applied by the liquid medium to an outer surface of an accordion portion of the bellows. Meanwhile, by increasing an inner volume of the accordion portion, an inner surface of the accordion portion becomes a negative pressure state. When a pressure difference between the positive pressure of the outer surface and the negative pressure of the inner surface of the accordion portion of the bellows exceeds a predetermined value, an outer diameter of the accordion portion is deformed in a direction of becoming small. Meanwhile, by contracting the bellows to expand the tube via the fluid medium, the outer surface of the accordion portion of the bellows become the negative pressure when the liquid is injected into the pump chamber. Meanwhile, by decreasing the inner volume of the accordion portion, the positive pressure is applied to the inner surface of the accordion portion. When the pressure difference between the negative pressure of the outer surface and the positive pressure of the inner surface of the accordion portion of the bellows exceeds the predetermined value, an outer diameter of the accordion portion is deformed in a direction of becoming large.

Thus, it is conceivable that when the tubephragm is contracted to discharge the liquid from the pump chamber to the outside, a discharge amount according to an extension stroke of the bellows is different from a set value and when the tubephragm is expanded to inject the liquid into the pump chamber, a suction amount according to the contraction stroke of the bellows is different from the set value. In this way, when an effective diameter in the radial direction of the accordion portion is different between an extension time and a contraction time of the bellows, the liquid cannot be discharged from the pump chamber toward the liquid discharge portion with high accuracy and discharge accuracy of the liquid is reduced.

Also, when the bellows is contracted to inject the liquid into the pump chamber and when the outer surface of the accordion portion has a lower pressure than the inner surface, air in the air chamber inside the accordion portion may penetrate the bellows made of a resin material and mix into the liquid medium. When air is mixed into the liquid medium, the discharge accuracy of the liquid from the pump chamber is reduced. In this way, the reduction in the discharge accuracy similarly occurs in the liquid supply device having the pump operation by using the bellows and the diaphragm as the flexible member partitioning the pump chamber and the air chamber.

An object of the present invention is to provide a liquid supply device that performs the pump operation by means of the flexible member, enlargement of the pressure difference between the inside and outside of the flexible member being suppressed and the discharge accuracy of the liquid being enhanced.

Means for Solving the Problems

A liquid supply device according to one embodiment is arranged in a pump case, has a first flexible member for partitioning a pump chamber and a pump accommodation chamber, increases a volume of the pump chamber to inject a liquid into the pump chamber, and reduces the volume of the pump chamber to discharge the liquid in the pump chamber to an outside, the liquid supply device including: a media accommodation case having a second flexible member for partitioning a medium accommodation chamber communicating with the pump accommodation chamber and an air chamber; a liquid medium filled in the pump accommodation chamber and the medium accommodation chamber; a drive member reciprocating a rod in a discharge direction of supplying the liquid medium from the medium accommodation chamber to the pump accommodation chamber and an injection direction of returning the liquid medium from the pump accommodation chamber to the medium accommodation chamber, the rod being attached to the second flexible member; and a pressure adjustment mechanism for reducing a pressure of the air chamber when the rod is driven in the injection direction to reduce the volume of the air chamber.

A liquid supply device according to another embodiment is arranged in a pump case, has a flexible member for partitioning a pump chamber and an air chamber, increases a volume of the pump chamber to inject a liquid into the pump chamber, and reduces the volume of the pump chamber to discharge the liquid in the pump chamber to an outside, the liquid supply device including: a drive member for reciprocating a rod between a discharge direction of discharging the liquid in the pump chamber to the outside and an injection direction of injecting the liquid into the pump chamber, the rod being attached to the flexible member; and a pressure adjustment mechanism for reducing a pressure of the air chamber when the rod is moved in the injection direction to reduce the volume of the air chamber.

Effects of the Invention

In the liquid supply device performing the pump operation by the first and second flexible members, when the first flexible member increases the volume of the pump chamber to inject the liquid into the pump chamber, the pressure in the medium accommodation chamber contacting with the outer surface of the second flexible member decreases. Meanwhile, the pressure in the air chamber contacting with the inner surface of the second flexible member decreases by the pressure adjustment mechanism according to the pressure of the medium accommodation chamber or the contraction of the second flexible member. Consequently, since the pressure difference between the medium accommodation chamber and the air chamber becomes small, it is possible to suppress a risk of the air in the air chamber passing through the second flexible member and being mixed into the medium accommodation chamber, to suppress the volume of the air chamber being excessively deformed in the enlarging direction, and to maintain the pump characteristics for a long period of time with high accuracy.

In the liquid supply device performing the pump operation by the flexible member for partitioning the pump chamber and the air chamber, when the volume of the pump chamber is increased to inject the liquid into the pump chamber, the pressure in the pump chamber decreases with respect to the air chamber, but the pressure in the air chamber is reduced by the pressure adjustment mechanism according to the pump chamber. Consequently, since the pressure difference between the pump chamber and the air chamber, it is possible to suppress a risk of the air in the air chamber passing through the flexible member and being mixed into the medium accommodation chamber, to suppress the volume of the air chamber being excessively deformed in the enlarging direction, and to maintain the pump characteristics for a long period of time with high accuracy.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a cross-sectional view of a liquid supply apparatus according to one embodiment, and shows a state of expanding radially a tubular member as a first flexible member to inject a liquid into a pump chamber;

FIG. 2 is a cross-sectional view showing the liquid supply apparatus in a state of contracting radially the tubephragm to discharge the liquid from the pump chamber to an outside;

FIG. 3 is an enlarged cross-sectional view of a pressure adjustment piston shown in FIGS. 1 and 2;

FIG. 4 is a cross-sectional view of a liquid supply device according to another embodiment;

FIG. 5 is a pneumatic circuit diagram of a pneumatic control device shown in FIG. 4;

FIG. 6 is a cross-sectional view of a liquid supply device according to another embodiment;

FIG. 7 is a cross-sectional view of a liquid supply device according to yet another embodiment; and

FIG. 8 is a pneumatic circuit diagram of a pressure adjustment mechanism of the liquid supply device shown in FIGS. 6 and 7.

DETAILED DESCRIPTION

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. A liquid supply device 10a shown in FIGS. 1 to 3 includes a pump 11 and a pump drive unit 12. The pump 11 has a pump case 14 with a longitudinally penetrating accommodation hole 13, and a tubephragm as a first flexible member is arranged in the pump case. The tubephragm 15 is a flexible pump member that is formed of a resin material such as a fluororesin and is elastically deformable in a radial direction. The tubephragm 15 partitions an inner pump chamber 16 and an outer pump chamber 17. An inflow side joint 18 is provided at one end of the pump case 14 and an outflow side joint 19 is provided at the other end of the pump case 14.

When the inflow side joint 18 is connected to a liquid tank 22 by an inflow side pipe 21 and the outflow side joint 19 is connected to a liquid discharge portion 24 by an outflow side pipe 23, the liquid L in the liquid tank 22 can be discharged from the liquid discharge portion 24. The liquid discharged from the liquid discharge portion 24 is supplied to a coated object (not shown). The liquid L in the liquid tank 22 is injected into the pump chamber 16 when the tubephragm 15 is radially expanded to increase a volume of the pump chamber 16, and the liquid L in the pump chamber 16 is discharged to the outside toward the liquid discharge portion 24 when the tubephragm 15 is radially contracted to reduce the volume of the pump chamber 16.

A check valve 25 is provided in an inlet piping 21. The check valve 25 allows the liquid L in the liquid tank 22 to flow toward the pump chamber 16 via the inlet piping 21 when the volume of the pump chamber 16 is increased, and the check valve 24 blocks the liquid in the inlet piping 21 flowing back into the liquid tank 22 when the volume of the pump chamber 16 is reduced. A check valve 26 is provided in the outlet piping 23. The check valve 26 allows the liquid L of the pump chamber 16 to flow toward the liquid discharge portion 24 via the outflow side pipe 23 when the volume of the pump chamber 16 is reduced, and the check valve 26 blocks the liquid L in the outflow side piping 23 flowing back toward the pump chamber 16 when the volume of the pump chamber 16 is increased. Note that, in place of the check valves 25, 26, the inlet side piping 21 and the outflow side piping 23 may be provided with an electromagnetically operated or pneumatically operated on-off valve, and an operation of the on-off valve may be controlled according to the pump operation of the expansion and contraction of the tubephragm 15.

The pump drive unit 12 includes a media accommodation case 28. A bellows 31 as a second flexible member is attended to the medium accommodation case 28, and the bellows 31 has an accordion portion 31a, an end plate portion 31b provided at one end portion of the accordion portion 31a, and an annular base end portion 31c provided at the other end portion, and is integrally formed of a resin material such as a fluororesin. The accordion portion 31a is elastically deformable in an axial direction.

The bellows 31 partitions an outer media accommodation chamber 32 and an inner air chamber 33. The bellows 31 is a flexible partition member that is stretchable in the axial direction as a whole. The medium accommodation chamber 32 communicates with the pump accommodation chamber 17 by a communication hole 34 formed in the pump case 14 and the medium accommodation case 28. The pump accommodation chamber 17 and the medium accommodation chamber 32 are filled with a liquid medium M composed of a liquid, and the liquid medium M can move between the pump accommodation chamber 17 and the medium accommodation chamber 32 via the communication hole 34. Note that those can also be separated without attaching the pump 11 to the pump drive unit 12. In this case, a medium piping for guiding the liquid medium M is connected between the pump 11 and the medium accommodation case 28.

A cylinder 36 with an end plate 35 is attached to the media accommodation case 28, and a base end portion 31c of the bellows 31 is sandwiched between the end plate 35 and the media accommodation case 28. A drive mechanism 27 having a rod 44 and an electric motor 46 is attached to the cylinder 36, and the rod 44 is reciprocated by the drive mechanism 27. A linking plate 37 is attached to an opening end of the cylinder 36, and a support plate 39 to which a bearing 38 is attached is attached to the linking plate 37 via a side plate 41. The axially reciprocable rod 44, which penetrates through a through-hole 42 formed in the end plate 35 and a through-hole 43 formed in the linking plate 37, is arranged, and a male screw portion 45 provided at a tip of the rod 44 is screwed to an end plate portion 31b of the bellows 31.

To axially reciprocate the rod 44, an electric motor 46 is attached to the support plate 39 via a pedestal 47, and a main shaft 48 of the electric motor 46 is coupled to a feed screw shaft 51 by a coupling 49. A base end portion of the feed screw shaft 51 is rotatably supported by the bearing 38, and the tip portion of the feed screw shaft 51 protrudes into an accommodation hole 52 formed in the rod 44. An inner diameter of the accommodation hole 52 is larger than an outer diameter of the feed screw shaft 51. The feed screw shaft 51 is a ball screw and a nut 53 is screwed to the feed screw shaft 51 via a ball. The nut 53 is attached to the holder 54 and the holder 54 is secured to the base end portion of the rod 44. A guide rod 55 penetrates through the holder 54 in the axial direction, one end portion of a guide rod 55 being fixed to the linking plate 37, and the other end portion being fixed to the support plate 39. The holder 54 is guided by the guide rod 55 and moves axially without rotation. Note that although only one guide rod 55 is shown in FIGS. 1 and 2, a plurality of guide rods 55 are provided in the drive mechanism 27.

When the electric motor 46 as a drive member is driven, the rod 44 is axially moved by the feed screw shaft 51 via the nut 53 and the holder 54. Consequently, the bellows 31 is extended and contracted in the axial direction. FIG. 1 shows a case in which the tubephragm 15 is radially expanded and, under this condition, when the feed screw shaft 51 is rotated in one direction by the electric motor 46, the rod 44 moves in a direction of extending the bellows 31 and the bellows 31 extends. When the bellows 31 is extended, as shown in FIG. 2, the end plate portion 31b reduces the volume of the media accommodation chamber 32 and the liquid medium M in the media accommodation chamber 32 flows toward and into the pump accommodation chamber 17. When the liquid medium M flows into the pump accommodation chamber 17, the tubephragm 15 contracts radially and the liquid L already sucked from the liquid tank 22 into the pump chamber 16 is discharged toward the external liquid discharge portion 24. At this time, the check valve 25 prevents the liquid in the pump chamber 16 from flowing back to the inflow side piping 21.

Meanwhile, as shown in FIG. 2, under the condition that the tubephragm 15 is radially contracted, when the feed screw shaft 51 is rotated in a reverse direction to the direction as described above by the electric motor 46, the rod 44 moves in a direction of axially contracting the bellows 31 and the bellows 31 contracts. When the bellows 31 contracts, as shown in FIG. 1, the volume of the media accommodation chamber 32 increases and the liquid medium M in the pump accommodation chamber 17 flows toward and into the media accommodation chamber 32. When the liquid medium M in the pump accommodation chamber 17 flows toward and into the medium accommodation chamber 32, the tubephragm 15 expands radially and the liquid Lis sucked into the pump chamber 16 from the liquid tank 22. At this time, the check valve 26 prevents the liquid in the outflow side piping 23 from flowing toward and back the pump chamber 16.

Thus, the rod 44 is reciprocated in a discharge direction of supplying the liquid medium M from the medium accommodation chamber 32 to the pump accommodation chamber 17 by the electric motor 46 as a driving member and in a suction direction of returning the liquid medium M from the pump accommodation chamber 17 to the medium accommodation chamber 32. When the tubephragm 15 is radially expanded, the liquid L in the liquid tank 22 is sucked into the pump chamber 16 and when the tubephragm 15 is contracted radially, the liquid L in the pump chamber 16 is discharged to the outside.

When the fluid L is sucked from the liquid tank 22 into the pump chamber 16 by axially contracting the bellows 31 and radially expanding the tubephragm 15 via the liquid medium M, the outer surface of the accordion portion 31a of the bellows 31 become a lower pressure than the inner surface thereof. Therefore, when the bellows 31 is contracted axially, the bellows may be slightly deformed in the radial direction so that an average effective diameter of the accordion portion 31a increases. When the average effective diameter of the accordion portion 31a changes in a direction of increasing the average effective diameter, a predetermined amount of liquid is not injected into the pump chamber 16 and liquid discharge accuracy from the pump chamber 16 may be reduced. Furthermore, when the outer surface of the accordion portion 31a has a lower pressure than the inner surface, the gas in the air chamber 33 may permeate the bellows 31 of the resin material and be mixed into the liquid medium M. When outside air is mixed in the liquid medium M, the liquid discharge accuracy from the pump chamber 16 is reduced.

Meanwhile, when the liquid L from the pump chamber 16 is discharged into the outflow side piping 23 by axially extending the bellows 31 and contracting the tubephragm 15 via the liquid medium M, the pressure of the liquid medium M is applied to the outer surface of the accordion portion 31a of the bellows 31. Therefore, in axially extending the bellows 31, the bellows may be slightly deformed in the radial direction so that the average effective diameter of the accordion portion 31a becomes small. When the average effective diameter of the accordion portion 31a is reduced, the liquid discharge accuracy from the pump chamber 16 may be reduced. Note that even if the pressure on the outer surface of the accordion portion 31a becomes higher than the inner surface, the liquid medium M made of a liquid(s) permeates the bellows 31 and does not leak into the air chamber 33.

The pressure adjustment piston 56 is arranged in the cylinder 36, and the pressure adjustment piston 56 is attached to the rod 44 and is reciprocated in synchronization with the bellows 31. A pressure adjustment chamber 57 which is partitioned by the end plate 35 and the pressure adjustment piston 56 is formed in the cylinder 36. The communication hole 58 is formed in the end plate 35 of the cylinder 36, and the air chamber 33 communicates with the pressure adjustment chamber 57 by the communication hole 58. An outer diameter of the pressure adjustment piston 56 is set larger than the average effective diameter of the accordion portion 31a of the bellows 31. The pressure adjustment piston 56 configures the pressure adjustment mechanism 60, and when the bellows 31 is axially contracted by the rod 44 to radially expand the tubephragm 15 via the liquid medium M, the pressure adjustment piston 56 is larger in diameter than the average effective diameter of the accordion portion 31a, so that the air in the air chamber 33 is sucked into the pressure adjustment chamber 57.

Consequently, the pressure in the air chamber 33 decreases with the movement of the rod 44. As a result, since the pressure difference between the air chamber 33 and the medium accommodation chamber 32 is reduced, the risk of air in the air chamber 33 penetrating through the bellows 31 and being mixed into the medium accommodation chamber 32 can be suppressed and pump characteristics can be maintained with high accuracy over a long period of time. Further, when the bellows 31 is contracted, deformation of the accordion portion 31a in a direction in which the average effective diameter increases in the radial direction is suppressed and an amount of the liquid L injected into the pump chamber 16 can be set with high accuracy.

When the pressure adjustment mechanism 60 having the pressure adjustment piston 56 extends the bellows 31 by the rod 44 to radially contract the tubephragm 15 via the liquid medium M, the air in the pressure adjustment chamber 57 having a larger diameter than the air chamber 33 is supplied into the air chamber 33 and the pressure in the air chamber 33 is increased with the movement of the rod 44.

Consequently, when the bellows 31 is extended, the deformation of the accordion portion 31a in a direction in which the average effective diameter decreases can be suppressed and a discharge amount of the liquid L discharged from the pump chamber 16 to the outside can be set with high accuracy.

By changing a rotation direction in a normal rotation direction and a reverse rotation direction of the electric motor 46, the tubephragm 15 can perform the pump operation. The rotation direction and a rotation speed of the electric motor 46 are controlled by a drive signal from a control unit (not shown). In the control unit, data of the number of revolutions in both normal and reverse directions corresponding to an expansion stroke of the bellows 31 is stored in the memory in advance.

FIG. 3 is an enlarged cross-sectional view of the pressure adjustment piston 56 shown in FIGS. 1 and 2. The pressure adjustment piston 56 is provided with a negative pressure relief valve 61 for negative pressure and a positive pressure relief valve 62.

The negative pressure relief valve 61 has a cylinder body 64a in which an outside air introduction hole 63a is formed, a valve seat 65a provided in the cylinder body 64a, and a valve shaft 68a provided with a valve member 66a and supported by the valve shaft guide 67a, a fixed sleeve 69a is attached between the valve seat 65a and the valve shaft guide 67a. A spring member 70a for applying a spring force in a direction of closing the outside air introduction hole 63a to the valve member 66a being attached between the valve member 66a and the valve shaft guide 67a. When the pressure of a pressure adjustment chamber 57 is lower than an allowable negative pressure determined by the spring constant of the spring member 70a or the like, that is, when a negative pressure value is increased, the valve member 66a is separated from the valve seat 65a and the outside air introduction hole 63a is opened. Then, the pressure adjustment chamber 57 is communicated with an outside of the drive mechanism 27, and the outside air is supplied to the pressure adjustment chamber 57. Consequently, when the bellows 31 is axially contracted to radially expand the tubephragm 15, it is suppressed that a differential pressure between the pressure in the air chamber 33 and the pressure in the medium accommodation chamber 32 becomes excessively large enough to deform the accordion portion 31a of the bellows 31.

The positive pressure relief valve 62 has: a cylinder body 64b in which an air discharge hole 63b is formed; a valve seat 65b provided in the cylinder body 64b; and a valve shaft 68b provided with a valve member 66b and supported by the valve shaft guide 67b, and a fixed sleeve 69b is attached between the valve seat 65b and the valve shaft guide 67b. A spring member 70b for applying a spring force in a direction of closing the air discharge hole 63b to the valve member 66b is attached between the valve member 66b and the valve shaft guide 67b. When the pressure of the pressure adjustment chamber is higher than an allowable positive pressure determined by a spring constant or the like of the spring member 70b, the valve member 66b is separated from the valve seat 65b and the air in the pressure adjustment chamber 57 is discharged to the outside of the pump drive unit 12 by the air discharge hole 63b. Consequently, it is suppressed that the differential pressure between the pressure in the air chamber 33 and the pressure in the medium accommodation chamber 32 becomes magnitude of such an excessive positive pressure differential pressure that the accordion portion 31a of the bellows 31 is deformed when the bellows 31 is axially extended to radially contract the tubephragm 15.

The negative pressure relief valve 61 and the positive pressure relief valve 2 have the valve axes 68a, 68b opposite to each other as described above, but the components have commonality. Note that if the rod 44 and the pressure adjustment piston 56 can be moved synchronously, the rod 44 and the pressure adjustment piston 56 may be moved by separate electric motors. When the bellows 31 is axially expanded and contracted and if the pressure in the air chamber 33 and the differential pressure in the medium accommodation chamber 32 do not become too large to deform the accordion portion 31a of the bellows 31, the pressure adjustment piston 56 may not be provided with the negative pressure relief valve 61 and the positive pressure relief valve 62.

FIG. 4 is a cross-sectional view showing a liquid supply apparatus 10b according to another embodiment. In FIG. 4, members having commonality with the members configuring the liquid supply apparatus 10a described above are denoted by the same reference numerals, and an overlapped description thereof will be omitted.

The pump 11 has a pump case 14 in which an accommodation hole 13 is formed, similar to those shown in FIGS. 1 and 2, and a radially elastically deformable tubephragm 15 formed of a resin material such as a fluororesin is arranged in the pump case 14 as a first flexible member. An inlet side joint 18 is provided at one end of the pump case 14 and an outlet side joint 19 is provided at the other end of the pump case 14. In FIG. 4, the inflow side piping 21 connected to the inflow side joint 18, the outflow side piping 23 connected to the outflow side joint 19, and the like are omitted.

The pump drive unit 12 has a media accommodation case 28 attached to the pump 11, and a bellows 31 as a second flexible member is attached into the media accommodation case 28. The bellows 31 has an accordion portion 31a, an end plate portion 31b provided at one end portion of the accordion portion 31a, and an annular base end portion 31c provided at the other end portion, and is integrally formed by an axially expandable resin material such as a fluororesin.

The bellows 31 partitions the outer media accommodation chamber 32 and the inner air chamber 33. The medium accommodation chamber 32 communicates with the pump accommodation chamber 17 by a communication hole 34 formed in the pump case 14 and the medium accommodation case 28. The pump accommodation chamber 17 and the medium accommodation chamber 32 are filled with a liquid medium M composed of a liquid.

An end plate 71 is fixed to an opening side end portion of the medium accommodation case 28, and a base end portion 31c of the bellows 31 is sandwiched between the end plate 71 and the medium accommodation case 28. A rod 44, which penetrates through a through-hole 72 formed in the end plate 71 and is axially reciprocated, is attached, and a male screw portion 45 provided at the tip of the rod 44 is screwed to the end plate portion 31b. The support plate 73 is coupled to the end plate 71 by a coupling bar material 74, and the feed screw shaft 51 is rotatably supported at the support plate 73 by a bearing 75. A nut 53, which is screwed to the feed screw shaft 51 via the ball, is fixed to the holder 54, and the holder 54 is fixed to the rod 44.

One end portion of the guide rod 55 is fixed to the end plate 71, and the other end of the guide rod 55 is fixed to the support plate 73. The guide rod 55 axially penetrates through the holder 54 fixed to the rod 44, and the holder 54 is guided to the guide rod 55 by rotation of the feed screw shaft 51 and is moved axially without rotation.

The electric motor 46 for rotating the feed screw shaft 51 is attached to a base plate 76 attached to the support plate 73, and a belt 79 is bridged between a drive-side pulley 77 fixed to the main shaft 48 of the electric motor 46 and a driven-side pulley 78 fixed to the rod 44. The drive mechanism 27 having the belt 79 is housed in a case 81 attached to the pump 11.

A region between the rod 44 and the through-hole 72 of the end plate 71 is sealed by a seal member 82, and the air chamber 33 is a sealed space. When the inside of the medium accommodation chamber 32 becomes negative pressure, the negative pressure is supplied to the air chamber 33 correspondingly to the pressure in the medium accommodation chamber 32 by the pressure adjustment mechanism 60. The pressure adjustment mechanism 60 is formed by a pneumatic control mechanism 83, and FIG. 5 shows a pneumatic circuit diagram of a pneumatic control device configuring the pneumatic control mechanism 83.

As shown in FIGS. 4 and 5, the pneumatic control mechanism 83 includes a vacuum ejector 84. The vacuum ejector 84 is known well and includes an air supply port 85, a diffuser 86 to which compressed air supplied from the air supply port 85 is injected, and an exhaust port 87, a suction port 88 communicating with the diffuser 86 and being provided in the vacuum ejector 84. When compressed air is supplied from the air supply port 85 toward the diffuser 86, the suction port 88 is set to a negative pressure by air passing through the diffuser 86 and directed toward the exhaust port 87. The suction port 88 communicates with a suction hole 89 formed in the end plate 71 by a flow path 90.

The pressure of the compressed air supplied to the air supply port 85 is adjusted by a regulator 91. The regulator 91 is an external pilot operation type and, by the pressure supplied to a pilot airport 92, the pressure of the compressed air discharged from an input port 93 of the regulator 91 to a discharge port 94 is adjusted. As shown in FIG. 5, an air supply flow path 96 is connected to a compressed air supply source 95, and the air supply flow path is connected to the input port 93. An on-off valve 97 is provided in the air supply flow path 96. The regulator 91 may be an internal pilot operation type or a direct acting type. Further, it may be an electropneumatic regulator setting a pressure by an electric signal.

Also in the liquid supply device 10b shown in FIG. 4, when the liquid L is injected from the liquid tank 22 into the pump chamber 16 by axially contracting the bellows 31 and radially expanding the tubephragm 15 via the liquid medium M, the medium accommodation chamber 32 becomes negative. At this time, the on-off valve 97 is turned on, and the compressed air supplied from the compressed air supply source 95 is discharged to the air supply port 85 of the vacuum ejector 84. Accordingly, vacuum, that is, a negative pressure is generated in the suction port 88, and the air chamber 33 communicating with the suction port 88 by the flow path 90 is set to the negative pressure according to the pressure of the medium accommodation chamber 32. Also, the negative pressure generated by the vacuum ejector 84 by adjusting the pressure supplied from the regulator 91 may be adjusted to such a size that does not deform when the bellows 31 is extended, and while the on-off valve 97 is turned on, the rod 44 may be reciprocated to contract the bellows 31.

Consequently, a risk of the air in the air chamber 33 passing through the bellows 31 and being mixed into the medium accommodation chamber 32 can be suppressed, and the pump characteristics can be maintained with high accuracy over a long period of time. Further, when the bellows 31 is contracted, deformation of the accordion portion 31a in a direction in which the average effective diameter increases in the radial direction is suppressed, and the amount of the liquid L injected into the pump chamber 16 can be set with high accuracy.

The on/off operation of the on-off valve 97 is controlled according to the normal rotation and the reverse operation of the electric motor 46 by a control signal from a control unit (not shown).

In the liquid supply device shown in FIG. 4, a power transmission mechanism having a belt 79 is provided between the main shaft 48 of the electric motor 46 and the feed screw shaft 51, or the electric motor 46 may be disposed so that the main shaft 48 is coaxial with the feed screw shaft 51, similarly to the liquid supply device shown in FIGS. 1 and 2. Further, similarly, in the liquid supply apparatus shown in FIGS. 1 and 2, the main shaft 48 of the electric motor 46 may be connected to the feed screw shaft 51 via the power transmission mechanism.

FIG. 6 is a cross-sectional view of a quid supply device 10c according to another embodiment. This liquid supply device 10c is provided with a pump 11 using the tubephragm 15 as a first flexible member similarly to the liquid supply devices 10a and 10b described above. The media accommodation case 28 has a side wall 28b integrally provided with a top wall 28a, and an end plate 28c is attached to an opening end portion of the medium accommodation case 28. The medium accommodation case 28 is provided with a diaphragm 29 as a second flexible member that partitions an interior into the medium accommodation chamber 32 and the air chamber 33, the medium accommodation chamber 32 communicates with the pump accommodation chamber 17 by the communication hole 34.

The diaphragm 29 has an annular base portion 29a fixed between the side wall 28b and the end plate 28c, a central coupling portion 29b coupled to the rod 44, and an elastic deformation portion 29c therebetween, and is integrally formed of a resin material such as a fluororesin similarly to the bellows 31 described above. The rod 44 is reciprocated in the axial direction by the drive mechanism 27 and can reciprocate between a discharge direction in which the liquid medium M is supplied from the medium accommodation chamber 32 to the pump accommodation chamber and an injection direction in which the liquid medium M is returned from the pump accommodation chamber 17 to the medium accommodation chamber 32. The drive mechanism may be a mechanism for converting the rotational motion of the electric motor 46 into a linear reciprocating motion of the rod 44 as described above, and may be a mechanism for linearly reciprocating the rod 44 by the pressure of the fluid like a pneumatic cylinder and the like.

Thus, the rod 44 is moved by the drive mechanism 27 between the discharge direction in which the liquid medium M is supplied from the medium accommodation chamber 32 to the pump accommodation chamber 17 and the injection direction in which the liquid medium M is returned from the pump accommodation chamber 17 to the medium accommodation chamber 32. When the rod 44 is moved in the injection direction to inject the liquid L from the liquid tank 22 into the pump chamber 16, the outer surface of the diaphragm 29 has a lower pressure than the inner surface. Consequently, similarly to the bellows 31 described above, the elastic deformation portion 29c may be excessively deformed in the axial direction and the liquid discharge accuracy from the pump chamber 16 may be reduced. Furthermore, when the outer surface of the elastic deformation portion 29c has a lower pressure than the inner surface, it is conceivable that the gas in the air chamber 33 passes through the diaphragm 29 of the resin material and is mixed into the liquid medium M having a large negative pressure. When the outside air is mixed into the liquid medium M, the liquid discharge accuracy from the pump chamber 16 may be reduced.

In order to prevent a reduction in liquid discharge accuracy and in order to lower the pressure of the air chamber 33 when the rod 44 is moved in the injection direction to reduce the volume of the air chamber 33, a pressure adjustment mechanism 60 is connected to the suction hole 89 communicating with the air chamber 33 by the flow path 90. As the pressure adjustment mechanism 60, the air pressure control mechanism 83 shown in FIG. 5 can be applied.

FIG. 7 is a cross-sectional view of a liquid supply device 10d according to yet another embodiment. The pump case 14a forming the pump 11 in the liquid supply device 10d has the inflow side joint 18 and the outflow side joint 19 provided at one end portion, and the end plate 14b provided at the other end portion. In the pump case 14a, a bellows 31 having a structure similar to that of the bellows 31 shown in FIG. 1 is provided as a flexible member. The bellows 31 as a flexible member has an accordion portion 31a, an end plate portion 31b provided at one end portion of the accordion portion 31, and an annular base end portion 31c provided at the other end portion, and is integrally formed of a resin material such as a fluororesin. The accordion portion 31a is elastically deformable in the axial direction, and the bellows 31 is a flexible pump member that is expandable and contractable in the axial direction as a whole. The bellows 31 partitions the outer pump chamber 16 and the inner air chamber 33, and the pump case 14a is provided with the pump chamber 16 and the air chamber 33.

The rod 44a is attached to the end plate portion 31b, and the rod 44a is axially reciprocated by the drive mechanism 27. The rod 44a is reciprocally movable between the discharge direction for discharging the liquid in the pump chamber 16 to the outside and the injection direction for injecting the liquid into the pump chamber 16.

Thus, even in the liquid supply device 10d in the form in which the bellows 31 as a flexible member incorporated in the pump case 14 is directly expanded and contracted by the rod 44a, when the rod 44a is extended in the injection direction and the liquid L is injected from the liquid tank 22 into the pump chamber 16, the outer surface of the accordion portion 31a of the bellows 31 has a lower pressure than the inner surface. Consequently, when the bellows 31 is contracted in the axial direction, there is a possibility that the accordion portion 31a is slightly deformed in the radial direction so that the average effective diameter of the accordion portion 31a increases, and the liquid discharge accuracy from the pump chamber 16b may be reduced. Furthermore, when the outer surface of the accordion portion 31a has a lower pressure than the inner surface, it is conceivable that the gas in the air chamber 33 passes through the bellows 31 of the resin material and is mixed into the liquid medium M having a large negative pressure. When the outside air is mixed into the liquid medium M, the liquid discharge accuracy from the pump chamber 16 may be reduced.

Therefore, in order to prevent the reduction in liquid discharge accuracy and in order to lower the pressure of the air chamber 33 when the volume of the air chamber 33 is reduced by moving the rod 44a in the injection direction, the pressure adjustment mechanism 60 is connected to the suction hole 89 communicating with the air chamber 33 by the flow path 90. As the pressure adjustment mechanism 60, the pneumatic control mechanism 83 shown in FIG. 5 can be applied.

FIG. 8 shows a pneumatic circuit diagram of the pneumatic control mechanism 83 as an example of the pressure adjustment mechanism 60 in the liquid supply device shown in FIGS. 6 and 7.

The pneumatic control mechanism 83 includes a vacuum tank 102 connected to a vacuum pump 101. A predetermined amount of negative pressure air is stored in the vacuum tank 102 and functions as a buffer tank when there is a pressure variation. A vacuum flow path 103 connected to the vacuum tank 102 is provided with an on-off valve 97 and a regulator 104, and the flow path 90 connected to an output port of the regulator 104 is connected to the suction holes 89 of the liquid supply devices 10c, 10d. Thus, when the volume of the air chamber 33 is reduced to lower the pressure of the air chamber 33, the on-off valve 97 opens the vacuum flow path 103 to supply negative pressure air to the air chamber 33.

The air pressure control mechanism 83 in this form can also be applied as the pneumatic control mechanism 83 of the liquid supply device 10b shown in FIG. 4.

The invention is not limited to the embodiments described above, but can variably be altered without departing from the spirit thereof. For example, in the liquid supply devices 10a, 10b in the form of increasing or decreasing the volume of the pump chamber 16 via the liquid medium M, the first flexible member may be used to apply the bellows 31 shown in FIG. 7 or the diaphragm 29 shown in FIG. 6 instead of the tubephragm 15. Alternatively, the second flexible member may be used to apply the diaphragm 29 shown in FIG. 6 instead of the bellows 31.

INDUSTRIAL APPLICABILITY

The liquid supply device is applied to supply the liquid to the coated object, for example, when the photoresist liquid is supplied to the surface of the substrate or the electrolyte is supplied to the battery container.

While the present disclosure has been illustrated and described with respect to a particular embodiment thereof, it should be appreciated by those of ordinary skill in the art that various modifications to this disclosure may be made without departing from the spirit and scope of the present disclosure.

Claims

1. A liquid supply device arranged in a pump case, having a first flexible member for partitioning a pump chamber and a pump accommodation chamber, increasing a volume of the pump chamber to inject a liquid into the pump chamber, and reducing the volume of the pump chamber to discharge the liquid in the pump chamber to an outside, the liquid supply device comprising: a media accommodation case having a second flexible member for partitioning a medium accommodation chamber communicating with the pump accommodation chamber and an air chamber;a liquid medium filled in the pump accommodation chamber and the medium accommodation chamber;a drive member reciprocating a rod in a discharge direction of supplying the liquid medium from the medium accommodation chamber to the pump accommodation chamber and an injection direction of returning the liquid medium from the pump accommodation chamber to the medium accommodation chamber, the rod being attached to the second flexible member; anda pressure adjustment mechanism for reducing a pressure of the air chamber when the rod is driven in the injection direction to reduce the volume of the air chamber.

2. The liquid supply device according to claim 1, wherein the pressure adjustment mechanism has: a cylinder in which a pressure adjustment chamber communicating with the air chamber is formed; and a pressure adjustment piston reciprocably accommodated axially in the cylinder, andthe pressure adjustment piston: sucks air in the air chamber into the pressure adjustment chamber when the rod is driven in the injection direction to reduce the volume of the air chamber; andsupplies air in the pressure adjustment chamber into the air chamber when the rod is driven in the discharge direction to increase the volume of the air chamber.

3. The liquid supply device according to claim 2, wherein the pressure adjustment piston is provided with a positive pressure relief valve for discharging the air in the pressure adjustment chamber to the outside when the pressure in the pressure adjustment chamber becomes higher than an allowable positive pressure, andthe pressure adjustment piston is provided with a negative pressure relief valve for supplying the air in the pressure adjustment chamber when the pressure in the pressure adjustment chamber becomes lower than an allowable negative pressure.

4. The liquid supply device according to claim 2, wherein the pressure adjustment piston is provided on the rod, and the rod causes the second flexible member and the pressure adjustment piston to reciprocate synchronously.

5. The liquid supply device according to claim 1, wherein the pressure adjustment mechanism is a vacuum ejector including: an air supply port communicating with an air supply source; a diffuser to which compressed air supplied from the air supply port is injected; and a suction port communicating with the diffuser and communicating with the air chamber.

6. The liquid supply device according to claim 5, wherein an on-off valve is provided in an air supply flow path between the air supply port and a supply source of compressed air, and when the rod is moved in the injection direction to return the liquid medium from the pump accommodation chamber to the medium accommodation chamber, the on-off valve opens the air supply flow path.

7. The liquid supply device according to claim 5, further comprising: an on-off valve provided in an air supply flow path between the air supply port and a supply source of compressed air; and a regulator provided between the on-off valve and the air supply port and adjusting the pressure of the compressed air supplied to the air supply port,wherein the on-off valve reciprocating the rod with on a state of opening the air supply flow path.

8. The liquid supply device according to claim 1, wherein the pressure adjustment mechanism is a vacuum pump having a vacuum flow path communicated with the air chamber.

9. The liquid supply device according to claim 8, wherein an on-off valve is provided in the vacuum flow path, and when the rod is moved in the injection direction to return the liquid medium from the pump accommodation chamber to the medium accommodation chamber, the on-off valve opens a vacuum flow path.

10. The liquid supply device according to claim 1, wherein the first flexible member is any of: a tubephragm elastically deformable in a radial direction, the pump chamber being provided inside, and the pump accommodation chamber being provided outside; a bellows elastically deformable in an axial direction, the pump chamber being provided inside, and the pump chamber being provided outside; and a diaphragm elastically deformable in the axial direction, the pump chamber being formed outside, and the pump accommodation chamber being formed inside.

11. The liquid supply device according to claim 1, wherein the second flexible member is any one: a bellows elastically deformable in the axial direction, the air chamber being provided inside, the medium accommodation chamber being provided outside; or a diaphragm elastically deformable in the axial direction, the medium accommodation chamber being formed outside, and the air chamber being formed inside.

12. A liquid supply device arranged in a pump case, having a flexible member for partitioning a pump chamber and an air chamber, increasing a volume of the pump chamber to inject a liquid into the pump chamber, and reducing the volume of the pump chamber to discharge the liquid in the pump chamber to an outside, the liquid supply device comprising: a drive member for reciprocating a rod between a discharge direction of discharging the liquid in the pump chamber to the outside and an injection direction of injecting the liquid into the pump chamber, the rod being attached to the flexible member; anda pressure adjustment mechanism for reducing a pressure of the air chamber when the rod is moved in the injection direction to reduce the volume of the air chamber.

13. The liquid supply device according to claim 12, wherein the flexible member is any one of: a bellows elastically deformable in an axial direction, the pump chamber being provided outside, and the air chamber being provided inside; or a diaphragm elastically deformable in the axial direction, the pump chamber being formed outside, and the air chamber being formed inside.