Reciprocating pump and check valve   

This application is based upon and claims the benefit of priority from prior Japanese Patent Application No.2009-239266, filed on Oct. 16, 2009, the entire contents of which are incorporated herein by reference.

1. Field

Embodiments described herein relate to a reciprocating pump which introduces a liquid into a pump chamber from a tank, etc. through a pipe and a suction valve and discharges the liquid from the pump chamber through a discharge valve and a pipe by reciprocating movement of a reciprocating member driven by an actuation means, and a check valve used for the reciprocating pump.

2. Description of the Related Art

Conventionally, in order to prevent backflow, etc. of a liquid to deliver, reciprocating pumps which utilize reciprocating movement of a diaphragm, etc. use, as a suction valve and a discharge valve, check valves comprising a valving element such as a valve ball, etc. which can open and close a liquid flow path (JPH09-203380A). Meanwhile, reciprocating pumps such as electromagnetic pumps, etc. are required to become more accurate and more downsized. However, downsizing of pumps inevitably leads to a reduction of the amount of volumetric change in the pump chamber, which raises an issue of how to realize an efficient pumping operation. In order to improve the pump efficiency, it is effective to improve the checking performance of the suction valve and the discharge valve.

SUMMARY

A reciprocating pump according to one aspect of the invention introduces a liquid into a pump chamber through a suction valve and discharges the liquid from the pump chamber through a discharge valve by reciprocating movement of a reciprocating member facing the pump chamber. The suction valve and the discharge valve each include: a body portion having therein a flow path for a liquid; a valve seat portion provided at an entrance side of the flow path of the body portion and having therein a hole through which the liquid flows; a valving element provided in the body portion and able to open and close the hole of the valve seat portion; and a spring provided in the body portion for pressing the valving element into the hole of the valve seat portion. The spring has projections, which are formed on an outer circumferential portion of its surface to project toward the inner wall of the body portion.

The reciprocating pump according to the aspect is suitable for downsizing, because the use of a spring in the suction valve and the discharge valve improves the checking performance in the suction step and the discharge step and hence improves the pump efficiency.

In the reciprocating pump according to the aspect, the spring may be made of resin, which enables the pump to be used with no problem even for delivering a chemical liquid having metal corrosivity.

In the reciprocating pump according to the aspect, the suction valve and the discharge valve may be connected to a pump head in parallel with each other such that they protrude from the pump head in a direction of a central axis of the pump head. With the suction valve and the discharge valve connected to the pump head in parallel with each other such that they protrude from the pump head in this way, the pump is compact on the whole with no protrusion in the direction orthogonal to the central axis, and can advantageously provide a high degree of attaching latitude when it is attached to another device.

A check valve according to another aspect of the invention includes: a body portion having therein a flow path for a liquid; a valve seat portion provided at an entrance side of the flow path of the body portion and having therein a hole through which the liquid flows; a valving element provided in the body portion and able to open and close the hole of the valve seat portion; and a spring provided in the body portion for pressing the valving element into the hole of the valve seat portion. The spring has projections, which are formed on an outer circumferential portion of its surface to project toward an inner wall of the body portion.

By forming projections on the outer circumferential portion of the spring surface, the check valve according to the aspect can reduce the sliding resistance of the spring against the inner wall of the body portion.

According to the aspect, it is possible to provide a reciprocating pump which can be accurate and downsized. It is also possible to provide a check valve suitable for a reciprocating pump which can be accurate and downsized.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective diagram showing a reciprocating pump according to one embodiment of the present invention.

FIG. 2 is a sectional diagram of FIG. 1 taken along a line A-A′.

FIG. 3 is a partially enlarged sectional diagram showing check valves of the reciprocating pump according to the embodiment and their vicinity.

FIG. 4A is a plan diagram showing a spring used in the check valves of the reciprocating pump according to the embodiment.

FIG. 4B is a front diagram showing the spring used in the check valves of the reciprocating pump according to the embodiment.

FIG. 5 is a perspective diagram showing the spring used in the check valves of the reciprocating pump according to the embodiment.

DETAILED DESCRIPTION

Next, a reciprocating pump and a check valve according to one embodiment of the present invention will be explained with reference to the drawings. The reciprocating pump according to the present embodiment is a diaphragm pump which introduces a liquid into a pump chamber from a tank, etc. through a pipe and a suction valve and discharges the liquid from the pump chamber through a discharge valve and a pipe by reciprocating movement of a drive shaft and a diaphragm driven by an electromagnetic actuation means.

FIG. 1 is a perspective diagram showing the diaphragm pump according to the present embodiment. FIG. 2 is a sectional diagram of FIG. 1 taken along a line A-A′. The diaphragm pump 1 according to the present embodiment comprises: a pump head 2 in which a liquid inflow path and a liquid outflow path are formed; and an electromagnetic actuation unit 4 which is attached on the rear side of the pump head 2 and actuates the diaphragm pump 1.

The pump head 2 comprises: a pump head body 10 having an attachment portion 11 to which the electromagnetic actuation unit 4 is attached and having therein flow paths 12a and 12b which communicate with a pump chamber 6 described later; a suction valve unit 20 attached on the front side of the pump head body 10 to communicate with the flow path 12a of the pump head body 10; and a discharge valve unit 30 attached on the front side of the pump head body 10 in parallel with the suction valve unit 20 to communicate with the flow path 12b of the pump head body 10. The attachment portion 11 of the pump head body 10 has a recessed portion 13 which defines the pump chamber 6 in cooperation with a diaphragm 80 of the electromagnetic actuation unit 4 described later.

The suction valve unit 20 comprises: a check valve 21 provided to communicate with the pump chamber 6 through the flow path 12a of the pump head body 10; a joint 22 which supports the check valve 21 and has a screw for attaching to the front side of the pump head body 10; and a nut 23 attached on the leading end portion of the joint 22 and used for pipe connection. The discharge valve unit 30 is configured like the suction valve unit 20, and comprises: a check valve 31 provided to communicate with the pump chamber 6 through the flow path 12b of the pump head body 10; a joint 32 which supports the check valve 31 and has a screw; and a nut 33 used for pipe connection. The suction valve unit 20 and the discharge valve unit 30 are attached on the front side of the pump head body 10 with O-rings 24 and 34 interposed therebetween respectively.

FIG. 3 is a partially enlarged sectional diagram showing the check valves 21 and 31 of the diaphragm pump 1 according to the present embodiment and their vicinity. Because the check valve 31 is configured like the check valve 21, explanation about the check valve 31 is skipped to explain only the check valve 21. The check valve 21 comprises: a body portion 25 having therein a flow path for a flowing liquid; a valve seat portion 26 provided at the entrance side of the flow path of the body portion 25 and having therein a hole 26a through which a liquid flows; a spherical valving element 27 having a size enough to close the hole 26a of the valve seat portion 26; and a spring 28 which secures a certain back pressure by pressing the valving element 27 against the valve seat portion 26. The body portion 25 and the valve seat portion 26 define a cylindrical space in which the valving element 27 can slightly move, and the valving element 27 and the spring 28 are contained in this cylindrical space. The body portion 25 has a restricting portion 25a, which protrudes toward the inside from the exit side of the flow path for restricting excessive movement of the valving element 27 in the cylindrical space.

FIG. 4 shows a plan diagram and a front diagram of the spring 28 used in the check valve 21 of the diaphragm pump 1 according to the present embodiment. FIG. 5 is a perspective diagram of the spring 28. The spring 28 of the check valve 21 comprises a top end portion 28a and a bottom end portion 28b both having an annular shape, and a helical linking portion 28c which links the top end portion 28a and the bottom end portion 28b. These portions are formed integrally from a resin suitable as a spring material. Resin suitable for the spring 28 may be, for example, PEEK (polyether ether ketone), PC (polycarbonate), POM (polyacetal), etc. As shown in FIG. 4A and FIG. 4B, the top end portion 28a and the bottom end portion 28b of the spring 28 have a plurality of projections 29, which project outward from the surfaces thereof and are formed at approximately 45-degree intervals on the outer circumferential surfaces thereof. As shown in FIG. 4B and FIG. 5, the linking portion 28c of the spring 28 has a plurality of projections 29, which project outward from the surface thereof and are formed at approximately 180-degree intervals on the helical outer circumferential surface thereof. The spring 28 formed in this way is contained in the cylindrical space defined by the body portion 25 and the valve seat portion 26 such that the projections 29 formed on the top end portion 28a, the bottom end portion 28b, and the linking portion 28c make point contact with the inner wall of the body portion 25.

As shown in FIG. 1, the electromagnetic actuation unit 4 comprises: a cylindrical frame 40; a fixed portion 50 fixed on the frame 40; a movable portion 60 movable with respect to the fixed portion 50; a magnet coil 70 which actuates the movable portion 60 by a magnetic force; and a diaphragm 80 attached on the front surface 40a of the frame 40. The electromagnetic actuation unit 4 is connected to a power supply (not shown) and to a control device (not shown) through a connector 7 and a conductive wire 8.

The diaphragm 80 has flexibility. Therefore, when the pump head body 10 is attached at its attachment portion 11 to the front surface 40a of the frame 40, the circumferential edge portion of the diaphragm 80 is held between the front surface 40a of the frame 40 and the attachment portion 11 of the pump head body 10 and the front surface of the diaphragm 80 defines the pump chamber 6 in cooperation with the recessed portion 13 of the pump head body 10. The diaphragm 80 is coupled through a diaphragm coupler 62 to the leading end portion of a rod-like plunger 61 configuring the movable portion 60. The plunger 61 is supported in a center hole of a fixed sleeve 51 configuring the fixed portion 50 with a thrust bearing 52 provided between the plunger 61 and the fixed sleeve 51 such that the plunger 61 is freely movable in the axial direction. A plunger core 63 is fixed on the rear end of the plunger 61. The plunger core 63 is supported on the fixed portion 50 with a thrust bearing 53 provided therebetween such that the plunger core 63 is freely movable in the axial direction. The front surface of the plunger core 63 faces the rear end surface of the fixed sleeve 51 with a certain gap therebetween. A return spring 64 is provided between the inner circumferential surface of the fixed sleeve 51 and the outer circumferential surface of the plunger 61. With the return spring 64 fitted between the front surface of the plunger core 63 and the fixed sleeve 51, the plunger 61 is always biased rearward through the plunger core 63. An O-ring (not shown) as a shock absorber is provided on the front surface of the plunger core 63. The plunger 61, the diaphragm coupler 62, the plunger core 63, the return spring 64, and the O-ring configure the movable portion 60.

The fixed portion 50 comprises the fixed sleeve 51 supporting the plunger 61, and a coil holder 54 provided to extend from the fixed sleeve 51 to the plunger core 63 to surround them. The coil holder 54 is fitted with the magnet coil 70.

Next, a working of the diaphragm pump 1 configured in this way will be explained. First, the electromagnetic actuation unit 4 is energized by operating the power supply and control device (not shown). When the magnet coil 70 of the electromagnetic actuation unit 4 is energized, the plunger core 63 is moved frontward by an electromagnetic force. When the energization of the magnet coil 70 is stopped, the plunger 61 is moved rearward by the spring force of the return spring 64. At this time, the control device controls the energization frequency of the magnet coil 70, thereby controlling the frequency of the reciprocating movement of the plunger 61.

In a suction stroke in which the diaphragm 80 is moved rearward together with the plunger 61, the pump chamber 6 becomes a negatively-pressured state inside. Therefore, the check valve 21 of the suction valve unit 20 is opened and the check valve 31 of the discharge valve unit 30 is closed, thereby introducing a liquid into the pump chamber 6 from a tank (not shown) through the joint 22, the check valve 21, and the flow path 12a of the pump head body 10. Next, in a discharge stroke in which the diaphragm 80 is moved frontward together with the plunger 61, the fluid pressures in the pump chamber 6 and in the flow path 12b of the pump head body 10 become higher than the back pressure provided by the spring 28 of the check valve 31. Therefore, the check valve 21 of the suction valve unit 20 is closed and the check valve 31 of the discharge valve unit 30 is opened, thereby discharging the liquid in the pump chamber 6 to a discharge-side hose (not shown) through the flow path 12b of the pump head body 10, the check valve 31, and the joint 32. Here, the check valves 21 and 31 are opened or closed in response to the hole 26a of the valve seat portion 26 being opened or closed as the spring 28 is contracted or expanded by the fluid pressure or the spring force of the spring 28 aided by the valving element 27.

The diaphragm pump according to the present embodiment described above is suitable for downsizing, because it uses the springs 28 in the check valves 21 and 31 and this enables itself to demonstrate a better checking performance in the suction step and the discharge step and thereby improve the pump efficiency. Moreover, the springs 28 are made of resin and thus can be used with no problem even for delivering a chemical liquid having metal corrosivity.

When check valves are used in such suction valve unit 20 and discharge valve unit 30 as above, and besides, the springs 28 are made of resin, there are risks of checking performance deterioration and friction due to the sliding resistance caused by the reciprocating movement. However, the diaphragm pump according to the present embodiment can reduce the sliding resistance because the projections 29 are formed on the outer circumference of the springs 28.

In the present embodiment, the suction valve unit 20 and the discharge valve unit 30 are provided on the front surface of the pump head 2 such that they protrude in parallel with the direction of the central axis of the pump head 2 and electromagnetic actuation unit 4 coaxial with the pump head 2, and such that they are contained inside the range of the outer frame of the pump head 2 and electromagnetic actuation unit 4, provided that the outer frame is extended in the axial direction of the pump head 2 and electromagnetic actuation unit 4. Therefore, the pump is compact on the whole with no protrusion in the direction orthogonal to the central axis, and can advantageously provide a high degree of attaching latitude when it is attached to another device.

The reciprocating pump according to the present embodiment has been a diaphragm pump, but is not limited to this and may be such reciprocating pumps as a bellows pump, a tubephragm pump, etc.

While certain embodiments of the inventions have been described, these embodiments have been presented by way of example only, and are not intended to limit the scope of the inventions. Indeed, the novel methods and systems described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the methods and systems described herein may be made without departing from the spirit of the inventions. The accompanying claims and their equivalents are intended to cover such forms or modifications as would fail within the scope and spirit of the inventions.