Diaphragm pump

This invention provides a diaphragm pump that decreases the number of components or improves workability in assembling. A crank (4) to which the output shaft (2a) of a motor (2) is pivotally attached has, in its upper surface, a ring-shaped insertion groove (5) with respect to the output shaft (2a) as the center. A projecting driving shaft (9b) is formed integrally with a driver (7). When the lower end (9c) of the driving shaft (9b) is inserted into the insertion groove (5), the axis (9d) tilts. When the crank (4) rotates, an engaging portion provided in the insertion groove (5) engages with the lower end (9c). The driving shaft (9b) rotates while changing the tilt direction of the axis (9d) following the rotation of the crank (4). Hence, when a diaphragm portion (12a) attached to the drive element (7a) of the driver (7) moves upward/downward, a pump chamber (18) expands/contracts so that a pump action is obtained.

TECHNICAL FIELD

The present invention relates to a diaphragm pump used to pressurize or depressurize a fluid supplied to a sphygmomanometer, household electric appliances, or the like.

BACKGROUND ART

A diaphragm pump of this type includes a motor serving as a driving source, a crank that rotates upon driving of the motor, a driving shaft fixed to a portion displaced from the rotation center of the crank while having one end tilted with respect to the rotation axis of the crank, a driver having a non-through hole for receiving the other end of the driving shaft and pivotally supported by the driving shaft to be rotatable, and a diaphragm to which a diaphragm portion configured to form a pump chamber at each oscillation end of the driver is attached (see patent literature 1).

In the diaphragm pump described in patent literature 1, when the crank rotates upon driving of the motor, the driving shaft rotates about the output shaft of the motor while changing its tilt direction. The oscillation ends of the driver thus sequentially reciprocally move. Hence, the pump chambers sequentially expand and contract. When the pump chamber expands, air is sucked from the atmosphere into the pump chamber. When the pump chamber contracts next, the air in it is supplied to a pressurization target such as a sphygmomanometer.

RELATED ART LITERATURE

Patent Literature

DISCLOSURE OF INVENTION

Problem to be Solved by the Invention

In the above-described diaphragm pump, the driving shaft that transmits the rotation operation of the crank to the driver as an oscillation operation is formed from a member different from the driver. It is therefore impossible to decrease the number of components.

When assembling the diaphragm pump, one end of the driving shaft is fixed in advance to the crank attached to the output shaft of the motor. Additionally, the diaphragm portions of the diaphragm are attached to the oscillation ends of the driver, respectively. Then, the other end of the driving shaft is inserted into the non-through hole provided in the driver. In the operation of inserting the driving shaft into the non-through hole, the non-through hole needs to be fitted, from above, on the driving shaft tilted with respect to the vertical direction in a state in which the opening of the non-through hole is orientated downward, that is, in a state in which the opening portion cannot be visually confirmed. This operation is cumbersome and needs experience and skill, leading to not only poor workability but also a bottleneck in assembly automation.

It is an object of the present invention to provide a diaphragm pump that decreases the number of components.

It is another object of the present invention to provide a diaphragm pump that improves workability in assembling and facilitates introduction of assembly automation.

Means of Solution to the Problem

In order to achieve the above-described object, according to the present invention, there is provided a diaphragm pump comprising a motor serving as a driving source, a crank that is rotated by the motor and has a ring-shaped insertion groove in an upper surface, a pump chamber that is formed from a diaphragm including a diaphragm portion and expands/contracts in accordance with reciprocal motion of the diaphragm portion, a driver that reciprocally moves the diaphragm portion by an oscillation operation, a driving shaft that projects from the driver and engages with the insertion groove of the crank with respect to a rotation axis of the crank as a center, and an engaging portion that is formed in the insertion groove, and engages with the driving shaft to make the driving shaft follow the rotation of the crank, wherein the driving shaft and the driver are integrally formed from a single material or different materials.

According to the present invention, there is also provided a diaphragm pump comprising a motor serving as a driving source, a crank that is rotated by the motor, a pump chamber that is formed from a diaphragm including a diaphragm portion and expands/contracts in accordance with reciprocal motion of the diaphragm portion, a driver that reciprocally moves the diaphragm portion by an oscillation operation, a driving shaft that projects from the driver and is connected to the crank, converts a rotation operation of the crank into an oscillation operation of the driver, and is pivotally supported to be rotatable at a portion displaced from a rotation axis of the crank while tilting with respect to the rotation axis, wherein the driving shaft and the driver are integrally formed from a single material.

Effect of the Invention

According to the present invention, since the driving shaft is formed integrally with the driver, the number of components can be decreased. In addition, the step of pivotally attaching the driving shaft in a tilted state to the crank is unnecessary.

In addition, since the driving shaft is inserted into not a hole but the insertion groove formed into a ring shape, the insertion operation becomes easy, and workability in assembly improves. Since the driving shaft is guided by the guide portion into the insertion groove, the driving shaft need not be aligned with the insertion groove at the time of assembly. It is therefore possible to easily introduce assembly automation.

Furthermore, since the driver is sandwiched between the crank and the diaphragm holder, the oscillation operation of the driver stabilizes, and the expansion/contraction operation of the pump chamber also stabilizes. It is therefore possible to regulate the pulsating flow of the supplied fluid.

BEST MODE FOR CARRYING OUT THE INVENTION

The present invention will now be described in detail with reference to the accompanying drawings. Note that “upper/lower” used to explain a direction in this specification indicates a direction in the drawings for the descriptive convenience, and does not always match the upper/lower direction when actually using a diaphragm pump according to the present invention.

A diaphragm pump according to the first embodiment of the present invention will be described below with reference toFIGS. 1 to 5A and 5B. A diaphragm pump1according to this embodiment includes a motor2serving as a driving source, as shown inFIG. 1. The motor2is attached, via bolts, to the outside of a bottom portion3aof a case3formed into a cylindrical shape with a closed bottom such that an output shaft2aprojects from a shaft hole formed in the bottom portion3ainto the case3.

A crank4is formed into an almost cylindrical shape and has a non-through hole4aextending in the vertical direction at the center of its bottom surface, in which the output shaft2aof the motor2is press-fitted and pivotally attached, as shown inFIG. 3C. An insertion groove5having a ring shape when viewed from the upper side and extending in the circumferential direction about the non-through hole4a(the rotation axis of the crank4) is formed in the upper surface of the crank4. A wall surface5aof the insertion groove5on the side of the crank4tilts upward by an angle α with respect to the vertical direction to the side of the non-through hole4a(the center of the crank4). The insertion groove5is partially provided with an engaging portion5b. When the crank4rotates, the engaging portion5bengages with a lower end9cof a driving shaft9b(to be described later) inserted into the insertion groove5and rotates the driving shaft9bfollowing the rotation of the crank4.

A conical guide portion6stands at a portion of the upper surface of the crank4surrounded by the insertion groove5, that is, at the center of the upper surface of the crank4. When viewed in a section, a side surface6aof the guide portion6tilts by an angle β larger than the angle α with respect to the vertical direction. The lower end of the side surface6aof the guide portion6and the upper end of the inner surface5aof the above-described insertion groove5are continuously formed.

A driver7includes three drive elements7awhich are integrally provided at equal angles (120°) in the circumferential direction when viewed from the upper side, as shown inFIG. 5A, and project in directions perpendicular to the thickness direction. The drive elements7aare formed to tilt downward a little at the same angle from the proximal end to the oscillation end, as shown inFIG. 4B. Each oscillation end has a diaphragm portion attachment hole7b.

As shown inFIG. 4B, an oscillation fulcrum shaft8having a semispherical upper end projects upward from the center of the upper surface of the driver7. In addition, at the center of the lower surface of the driver7, a support portion9formed into a cylindrical shape, a non-slidable contact portion9ahaving a truncated conical shape and provided at the lower end of the support portion9, and the driving shaft9bprovided at the lower end of the non-slidable contact portion9aare formed using a resin to be integrated with the driver7as a single member. The lower end9cof the driving shaft9bis formed into a semispherical shape. An axis9dof the driving shaft9bis oriented in a direction almost perpendicular to the extending directions of the drive elements7a. The driving shaft9band the oscillation fulcrum shaft8are provided on the axis9dof the driving shaft9bso as to be oriented in directions opposing each other via the driver7. A total length L2 of the driving shaft9bis larger than a depth L1 of the insertion groove5.

A diaphragm holder10is formed into an inverted cylindrical shape with a closed bottom and holds a diaphragm12to be described later. A bearing portion11athat is formed into a concave shape to support the oscillation fulcrum shaft8rotatably about the axis while being able to change the tilt angle of the oscillation fulcrum shaft8in the axial direction is provided at the center of the lower surface of a ceiling portion11. Three holding cylinders11b(only one holding cylinder11bis illustrated) each formed into a cylindrical shape are provided in the ceiling portion11at equal angles (120°) in the circumferential direction when viewed from the upper side.

The diaphragm12is made of a flexible material such as rubber and formed into an almost disk-like shape. Three thin diaphragm portions12aare provided at equal angles (120°) in the circumferential direction when viewed from the upper side. A piston portion12bis integrally provided under each diaphragm portion12a. A small-diameter portion12cis integrally provided at the lower end of the piston portion12b. Pump chambers (to be described later) are formed from the diaphragm12including the diaphragm portions12a.

A valve holder13serves as a partition formed into an almost cylindrical shape with a closed bottom and having a cylindrical portion13a. An engaging convex portion13bprojects from the center of the upper surface of the bottom portion. A cylindrical partition wall13cstands around the engaging convex portion13b. Three discharge holes13d(only one discharge hole13dis illustrated) are provided around the engaging convex portion13bon the bottom portion of the valve holder13at equal angles (120°) in the circumferential direction when viewed from the upper side. In addition, three suction holes13e(only one suction hole13eis illustrated) are provided around the partition wall13cat equal angles (120°) in the circumferential direction when viewed from the upper side.

Referring toFIGS. 1 and 2, a discharge valve14is formed into a hat shape and attached to the engaging convex portion13bto open/close the discharge holes13d. The discharge valve14regulates the backflow of a fluid from a discharge space20to be described later to pump chambers18. A suction valve15is formed into an umbrella shape to open/close the suction hole13e, and regulates the backflow of a fluid from the pump chamber18to the suction hole13e.

A cover16is formed into an inverted cylindrical shape with a closed bottom. The cover16has a cylindrical portion16aintegrally projecting downward from its periphery, and a partition wall16bformed into a cylindrical shape concentric to the cylindrical portion16aand integrally projecting downward from its center. A discharge cylinder portion16dhaving a discharge port16cintegrally stands at the center of the ceiling portion of the cover16. A suction cylinder portion16fhaving a suction port16e′ integrally stands at part of the periphery of the ceiling portion.

A method of assembling the diaphragm pump having the above-described structure will be described next. The suction valve15is attached to the valve holder13in advance. Additionally, the discharge valve14is attached to the engaging convex portion13b. After stacking the cover16on the valve holder13, the two members are sealed by welding or the like, thereby forming a valve holder assembly17. In this state, a suction space19that has a ring shape when viewed from the upper side and makes the suction holes13ecommunicate with the suction port16e, and the discharge space20that makes the discharge holes13dcommunicate with the discharge port16care formed between the cover16and the valve holder13.

Next, the motor2is attached to the case3by bolts (not shown). The non-through hole4aof the crank4is press-fitted on the output shaft2aof the motor2, thereby fixing the crank4on the output shaft2a.

Each diaphragm portion12aof the diaphragm12is inserted into a corresponding holding cylinder11bof the diaphragm holder10to place the diaphragm12on the diaphragm holder10. The small-diameter portion12cof each piston portion12bis attached to the diaphragm portion attachment hole7bof a corresponding drive element7aof the driver7, so that the oscillation fulcrum shaft8of the driver7abuts against the bearing portion11aof the diaphragm holder10. The driver7and the diaphragm12are thus assembled in the diaphragm holder10to form a diaphragm holder assembly22.

The valve holder assembly17is stacked on the diaphragm holder assembly22to form a pump assembly23. In this state, the three pump chambers18(only one pump chamber18is illustrated) are formed by the valve holder13and the diaphragm portions12aof the diaphragm12. The three sets of discharge holes13dand suction holes13ecorrespond to the pump chambers18, respectively. Next, the pump assembly23is lowered from above the case3down onto the case3, thereby inserting the lower end9cof the driving shaft9bof the driver7into the insertion groove5of the crank4. At this time, the conical guide portion6is provided at the portion of the crank4surrounded by the insertion groove5, and the lower end of the side surface6aof the guide portion6and the upper end of the inner surface5aof the insertion groove5are continuously formed. Hence, the lower end9cof the driving shaft9babuts against the side surface6aof the guide portion6, moves downward while being guided by the side surface6a, and is inserted into the insertion groove5.

In this state, as shown inFIG. 2, the lower end of the driver7is supported by the insertion groove5via the driving shaft9b, and the oscillation fulcrum shaft8at the upper end of the driver7abuts against the bearing portion11aof the diaphragm holder10. The driving shaft9binserted into the insertion groove5leans against the wall surface5aon the side of the non-through hole4a. The axis9dof the driving shaft9btilts by the angle α with respect to the vertical direction. Since the total length L2 of the driving shaft9bis larger than the depth L1 of the insertion groove5, and the outer peripheral surface of the non-slidable contact portion9atilts by the angle β, the outer peripheral surface of the non-slidable contact portion9ais spaced apart from the guide portion6and is in a non-contact state with respect to the guide portion6.

Since the driving shaft9bis inserted into not a hole but the insertion groove5formed into a ring shape, the insertion operation becomes easy, and workability in assembly improves. The lower end9cof the driving shaft9bis inserted into the insertion groove5of the crank4only by lowering the driver7. This obviates the cumbersome operation requiring experience and skill, that is, the operation of fitting the non-through hole, from above, on the driving shaft tilted with respect to the vertical direction in a state in which the opening of the non-through hole is orientated downward. In addition, since the guide portion6that guides the lower end9cof the driving shaft9bis provided in the insertion groove5, the lower end9ccan more reliably be inserted into the insertion groove5. It is therefore possible to easily introduce assembly automation.

The pump assembly23and the case3are integrated using a spring (not shown), thereby forming the diaphragm pump1.

The pump action of the diaphragm pump1having the above-described structure will be described next. When the motor2is driven to rotate the crank4via the output shaft2a, the engaging portion5bof the insertion groove5engages with the lower end9cof the driving shaft9b. The driving shaft9bthen rotates following the rotation of the crank4while remaining engaged with the engaging portion5band changing the tilt direction of the axis9d. Hence, the oscillation ends of the three drive elements7asequentially oscillate in the upward/downward direction.

When the oscillation end of the first drive element7amoves downward, the first pump chamber18expands via the piston portion12b, as shown inFIG. 1, and the air in the pump chamber18is set to a negative pressure. Hence, blocking of the suction hole13eby the suction valve15is canceled, and the suction hole13eis opened. In this state, air sucked from the external atmosphere via the suction port16eof the cover16passes through the suction hole13evia the suction space19and flows into the first pump chamber18.

Next, when the oscillation end of the drive element7aof the first pump chamber18that has expanded moves upward, the first pump chamber18contracts, as shown inFIG. 2, and the pressure of the air in the first pump chamber18rises. Blocking of the discharge hole13dby the discharge valve14is canceled, and the discharge hole13dis opened. The air in the first pump chamber18passes from the discharge hole13dthrough the discharge port16cvia the discharge space20and is supplied to a pressurization target connected to an air tube (not shown) or the like.

When the crank4further rotates via the output shaft2a, and the oscillation end of the second drive element7amoves downward, the second pump chamber18expands, and the air in the pump chamber18is set to a negative pressure. Hence, blocking of the suction hole13eby the suction valve15is canceled, and the suction hole13eis opened. In this state, air sucked from the external atmosphere via the suction port16eof the cover16passes through the suction hole13evia the suction space19and flows into the second pump chamber18.

Next, when the oscillation end of the drive element7aof the second pump chamber18that has expanded moves upward, the pump chamber18contracts, and the pressure of the air in the pump chamber18rises. Blocking of the discharge hole13dby the discharge valve14is canceled, and the discharge hole13dis opened. The air in the second pump chamber18passes from the discharge hole13dthrough the discharge port16cvia the discharge space20and is supplied to the pressurization target connected to the air tube (not shown) or the like.

When the crank4further rotates via the output shaft2a, and the oscillation end of the third drive element7amoves downward, the third pump chamber18expands, and the air in the pump chamber18is set to a negative pressure. Hence, blocking of the suction hole13eby the suction valve15is canceled, and the suction hole13eis opened. In this state, air sucked from the external atmosphere via the suction port16eof the cover16passes through the suction hole13evia the suction space19and flows into the third pump chamber18.

Next, when the oscillation end of the drive element7aof the third pump chamber18that has expanded moves upward, the pump chamber18contracts, and the pressure of the air in the third pump chamber18rises. Blocking of the discharge hole13dby the discharge valve14is canceled, and the discharge hole13dis opened. The air in the third pump chamber18passes from the discharge hole13dthrough the discharge port16cvia the discharge space20and is supplied to the pressurization target connected to the air tube (not shown) or the like. In this way, the three pump chambers18sequentially perform the expansion/contraction operation. Hence, the air with little pulsatile flow is continuously supplied from the discharge port16cto the pressurization target.

In addition, the upper end of the driver7is supported by the bearing portion11aof the diaphragm holder10via the oscillation fulcrum shaft8, and each drive element7aoscillates about the oscillation fulcrum shaft8. For this reason, each drive element7ahas a predetermined oscillation width, and a stable oscillation operation can be obtained. When the expansion/contraction operation of the pump chambers18stabilizes without variations, the amount of air supplied from the pump chambers18becomes constant. It is therefore possible to regulate a pulsating flow by the supplied air.

The second embodiment of the present invention will be described next with reference toFIG. 6. As the characteristic feature of the second embodiment, a driving shaft25is not formed using a resin to be integrated with a driver7but integrally formed as a member different from the driver7. For example, the driving shaft25made of a metal is integrally molded and unitized with the driver7made of a resin. A non-through hole9eis formed at the center of the lower end of a non-slidable contact portion9a. One end of the driving shaft25formed from a metal or slidable member is press-fitted and fixed in the non-through hole9e. When the driving shaft25that receives a relatively large load with respect to an insertion groove5is formed from a metal or slidable member, the durability and wear resistance of the driving shaft25can be improved.

The third embodiment of the present invention will be described next with reference toFIG. 7. As the characteristic feature of the third embodiment, a driving shaft9bis formed using a resin to be integrated with a driver7, whereas an oscillation fulcrum shaft26is formed from a member (material) different from the driver7. For example, the oscillation fulcrum shaft26made of a metal is integrally molded with the driver7made of a resin. A non-through hole7cis formed at the center of the upper surface of the driver7. One end of the oscillation fulcrum shaft26formed from a metal or slidable member is press-fitted and fixed in the non-through hole7c. The third embodiment is effective for a vacuum diaphragm pump in which a relatively large load acts on the oscillation fulcrum shaft26.

The fourth embodiment of the present invention will be described next with reference toFIG. 8. In the fourth embodiment, the above-described second and third embodiments are simultaneously employed. A driving shaft25and an oscillation fulcrum shaft26are formed from members (materials) different from a driver7. For example, the driving shaft25and the oscillation fulcrum shaft made of a metal are integrally molded and unitized with the driver7made of a resin. Having both the functions of the second and third embodiments, the fourth embodiment is applicable to both a pressurized type and a vacuum type and therefore has high versatility.

The fifth embodiment of the present invention will be described next with reference toFIG. 9. In the fifth embodiment, one driving shaft27is press-fitted and fixed in a through hole9fextending through a driver7and a support portion9. For example, the driving shaft27made of a metal is integrally molded and unitized with the driver7made of a resin. A lower portion27aof the driving shaft27projects downward from the support portion9and is inserted into an insertion groove5of a crank4described above. An upper portion27bprojecting upward from the driver7is supported by a bearing portion11aof a diaphragm holder10. In the fifth embodiment, since the one driving shaft27also serves as the oscillation fulcrum shaft, the number of components and the number of assembly steps can be decreased, as compared to the fourth embodiment.

According to the above-described embodiments, since the driving projection9bis formed integrally with the driver7, it need not be formed as another member, and the number of components can be decreased. In addition, the step of pivotally attaching the driving shaft in a tilted state to the crank4as in the related art is unnecessary.

Note that in the above-described embodiments, the insertion groove5extending in the circumferential direction is formed in the crank4. In place of the insertion groove5, a non-through hole may be used, which tilts with respect to the non-through hole4aat a position displaced from the non-through hole4aand, when the driving projection9bis inserted, pivotally and rotatably supports the driving projection9b. In the embodiments, a so-called three-cylinder diaphragm pump including the three pump chambers18has been described. The embodiments are also applicable to a diaphragm pump including two or less, or four or more cylinders, as a matter of course. The engaging portion5bis molded integrally with the crank4. However, the engaging portion5bmay be formed from a member different from the crank4using a slidable member or the like and fixed in the insertion groove5of the crank4by fitting or the like.

The guide portion6is formed into a conical shape. However, the present invention is not limited to this. The guide portion6may be formed into a columnar shape, or need only have a shape capable of guiding the driving shaft9babutting against it into the insertion groove5when the driver7is moved downward. A so-called three-cylinder diaphragm pump including the three pump chambers18has been described. The embodiments are also applicable to a diaphragm pump including two or less, or four or more cylinders, as a matter of course.

EXPLANATION OF THE REFERENCE NUMERALS AND SIGNS