Diaphragm pump

Abstract

A diaphragm pump is disclosed. The diaphragm pump converts rotation of a motor into reciprocating motion and drives a diaphragm. The diaphragm pump includes a partition configured to form a pump chamber together with a deformed portion of the diaphragm, a suction passage communicating with the pump chamber via a suction through-hole extending through the partition, and a suction valve configured to open / close the suction passage. A valve body of the suction valve includes a leakage structure configured to form a passage between the valve body and a seating surface of the partition.

Description

TECHNICAL FIELD

[0001] The present application relates to a diaphragm pump including a suction valve that comes into contact with or separates from a seat surface of a valve seat. BACKGROUND

[0002] There is a diaphragm pump configured to drive a diaphragm by converting rotation of a motor into reciprocating motion. In order to reduce the discharge flow rate of such a diaphragm pump, a method of reducing the rotation speed of the motor by lowering the voltage applied to the motor is generally employed.

[0003] In order to suppress the discharge flow rate to a very low flow rate by this method, it is necessary to significantly lower the voltage applied to the motor. However, if the applied voltage is too low, the motor can stop due to insufficient torque, or the rotation becomes unstable, causing the pulsation of the pump motion to become large. Therefore, it is not possible to obtain a stable low flow rate. Thus, it is difficult to suppress the discharge flow rate to a fairly low flow rate, such as 3% of the rated flow rate.

[0004] The present inventors believe that the above problem can be solved to some extent by providing a diaphragm pump with a leakage structure for intentionally leaking the pressure in the pump chamber. This is because the discharge flow rate can be suppressed to be lower even if the voltage applied to the motor is not significantly lowered to the extent that the motor stops due to insufficient torque or the rotation becomes unstable, because fluid leaks from the leakage structure.

[0005] For another purpose, a diaphragm pump with a leakage structure is disclosed in Japanese Utility Model Publication No. 62-43535 (Document 1) and Japanese Patent Publication No. 2001-73953 (Document 2). In Document 1, a protrusion is provided on a base that holds a diaphragm. When the diaphragm is in close contact with the base, a gap is formed at the end of the protrusion. Fluid partially leaks from the gap. In Document 2, a protrusion is provided on a valve seat of a check valve. Even in a state where the check valve is closed, a gap is formed around the protrusion, and fluid slightly flows out from the gap.

[0006] However, in the leakage structure disclosed in Document 1, if a foreign object is placed in the gap between the diaphragm and the protrusion on the base, the foreign object cannot be substantially removed, and thus the discharge flow rate cannot be reduced. Therefore, in the diaphragm pump with the leakage structure, the performance can be unstable.

[0007] In the leakage structure disclosed in Document 2, since the hardness of the valve seat is higher than that of the check valve, the valve body of the check valve that repeatedly comes into contact with the protrusion wears and dust is generated. Therefore, the durability of the diaphragm pump with the leakage structure is low. SUMMARY

[0008] An object of the present application is to provide a diaphragm pump capable of suppressing discharge flow to a very low flow rate and capable of improving performance stability and durability.

[0009] To achieve the above object of the present application, there is provided a diaphragm pump including a diaphragm including a deformation portion having a cup shape; a partition plate configured to close an opening portion of the deformation portion and form a pump chamber together with the deformation portion; a suction through-hole extending through the partition plate; a suction passage communicating with the pump chamber via the suction through-hole; a discharge through-hole extending through the partition plate; a discharge passage communicating with the pump chamber via the discharge through-hole; a drive mechanism configured to convert rotation of a motor into reciprocating motion and deform the deformation portion alternately in a direction in which a capacity of the pump chamber is increased and in a direction in which the capacity of the pump chamber is decreased; a suction valve attached to the partition plate and configured to open the suction passage in a stroke in which the capacity of the pump chamber is increased and close the suction passage in a stroke in which the capacity is not increased; and a discharge valve attached to the partition plate in the discharge passage and configured to open the discharge passage in a stroke in which the capacity of the pump chamber is decreased and close the discharge passage in a stroke in which the capacity is not decreased, wherein the partition plate includes a seating surface on a side facing the pump chamber, and the suction valve includes a valve body configured to be in contact with or separated from the seating surface, and the valve body includes a leakage structure configured to form a passage between the valve body and the seating surface. BRIEF DESCRIPTION OF DRAWINGS

[0010] Figure 1 is a sectional view of a diaphragm pump according to a first embodiment of the present application;

[0011] Figure 2 is a sectional view of a portion of a suction valve and a valve holder;

[0012] Figure 3 is a plan view of a suction valve;

[0013] Figure 4 is an enlarged sectional view of a portion of a suction valve; and

[0014] Figure 5 is an enlarged sectional view of a portion of a mold. DETAILED DESCRIPTION

[0015] Reference will now be made to Figures 1 to 5 A diaphragm pump according to an embodiment of the present application will now be described in detail.

[0016] Figure 1 The diaphragm pump 1 shown in FIG. 1 is attached to a pump head 2 located Figure 1The motor 2 is arranged at the lowermost position in the housing 3, and is driven by the motor 2. The diaphragm pump 1 according to the present embodiment is a pump that sucks and discharges air.

[0017] The diaphragm pump 1 includes a housing 3 fixed to the motor 2. Functional components constituting the diaphragm pump 1 are held by the housing 3. The housing 3 is formed in a cylindrical shape by combining a plurality of members in the axial direction of the motor 2, and is located on the same axis as the rotation shaft 4 of the motor 2.

[0018] The plurality of members constituting the housing 3 include a bottom body 5, a diaphragm holder 6, a valve holder 8, a cover body 9, and the like. The bottom body 5 is a member having a cylindrical shape with a bottom and attached to the motor 2. The diaphragm holder 6 is attached to an open portion of the bottom body 5. The valve holder 8 is a disc-shaped member (partition) attached to the diaphragm holder 6 in a state in which a diaphragm 7 described later is sandwiched between the valve holder 8 and the diaphragm holder 6. The cover body 9 is attached to the valve holder 8 while covering the valve holder 8.

[0019] The diaphragm 7 is held while being sandwiched between the diaphragm holder 6 and the valve holder 8. The diaphragm 7 includes a plurality of cup-shaped deformation portions 11 that are open to the valve holder 8. The deformation portions 11 are arranged in each of a plurality of regions formed by dividing the diaphragm 7 in the circumferential direction of the housing 3. An open portion of the deformation portion 11 is closed by the valve holder 8, and a pump chamber 12 is formed between the deformation portion 11 and the valve holder 8. That is, the valve holder 8 and the deformation portion 11 together form the pump chamber 12. A connecting member 13 protruding in a direction opposite to the pump chamber 12 is provided on a bottom wall 11a of the deformation portion 11 having a cup shape. A drive mechanism 21 is connected to the connecting member 13.

[0020] The drive mechanism 21 includes a crank body 22 attached to the rotation shaft 4 of the motor 2, a drive body 24 connected to the crank body 22 via a drive shaft 23, and the like. The crank body 22 is fixed to the rotation shaft 4, and rotates integrally with the rotation shaft 4. The drive shaft 23 is fixed to an eccentric portion of the crank body 22 while being inclined with respect to the rotation shaft 4 of the motor 2. The inclination direction of the drive shaft 23 is a direction in which the amount of eccentricity with respect to the rotation shaft 4 decreases at a distal end portion of the drive shaft 23.

[0021] The drive body 24 includes a columnar shaft portion 25 connected to the drive shaft 23, and a plurality of arm portions 26 protruding outward in a radial direction from the shaft portion 25. The arm portions 26 are provided for each of the deformation portions 11 of the diaphragm 7, and extend radially outward from the shaft portion 25. A through-hole 26a is formed in the arm portion 26. The connecting member 13 of the diaphragm 7 is engaged in the through-hole 26a. The connecting member 13 extends through the arm portion 26, and is fixed to the arm portion 26 in this state. Thus, the arm portion 26 is connected to each of the plurality of deformation portions 11 of the diaphragm 7.

[0022] According to the drive mechanism 21, when the rotation shaft 4 of the motor 2 rotates, the crank body 22 and the drive shaft 23 rotate around the rotation shaft 4. At this time, since the rotation of the drive body 24 is blocked by the diaphragm 7, the drive body 24 swings as the direction of the inclination of the drive shaft 23 changes. By this swing, the arm portion 26 pushes or pulls the deformation portion 11. In this way, the drive body 24 converts the rotation of the rotation shaft 4 into a reciprocating motion and transmits it to the deformation portion 11.

[0023] If the deformation portion 11 of the diaphragm 7 is pulled toward the motor 2 side by the arm portion 26 and the deformation portion 11 expands, the capacity of the pump chamber 12 increases. On the other hand, if the deformation portion 11 of the diaphragm 7 is pushed toward the valve holder 8 side by the arm portion 26 and the deformation portion 11 contracts, the capacity of the pump chamber 12 decreases. Therefore, when the crank body 22 continuously rotates, the state in which the capacity of the pump chamber 12 increases and the state in which the capacity decreases are alternately repeated.

[0024] The suction passage hole 32 and the discharge passage hole 33 are formed in the portion of the valve holder 8 that forms the wall of the pump chamber 12. The suction valve 31 is provided near the suction passage hole 32. The suction valve 31 is made of a rubber material and is attached to the valve holder 8 for each pump chamber 12. As Figure 2 shown, the suction valve 31 according to the present embodiment includes a shaft portion 31a that is inserted into a shaft hole 34 formed in the valve holder 8 and is fixed to the valve holder 8, and a valve body 31b that comes into contact with or separates from a seat surface 35 of a valve seat formed on the valve holder 8. The seat surface 35 is a smooth surface formed on the side of the valve holder 8 that faces the pump chamber 12.

[0025] The valve body 31b of the suction valve 31 is formed in a circular ring plate shape, as Figure 3 shown. As Figure 2 shown, the valve body 31b according to the present embodiment is formed in a shape that is curved to gradually approach the seat surface 35 toward the outer edge.

[0026] In addition, as Figure 4 shown, the valve body 31b includes a leakage structure 37 that is configured to form a minute passage 36 between the valve body 31b and the seat surface 35. The valve body 31b includes a sealing surface 38 that faces the seat surface 35, and a concave-convex portion 41 formed by a concave portion 39 and a convex portion 40 provided on the entire sealing surface 38 constitutes the leakage structure 37. The sealing surface 38 is formed in the range indicated by hatching in Figure 3 . In Figure 4 , the concave-convex portion 41 is drawn by a wavy curve to help understanding the configuration of the leakage structure 37. However, there can be a corner portion or a valley portion having a steep inclined surface in the concave-convex portion 41.

[0027] Note that as long as a channel 36 is formed from the suction port 32 into the pump chamber 12, the leakage structure 37 formed by the protrusion 41 does not always need to be provided on the entire sealing surface 38. For example, the leakage structure 37 formed by the protrusion 41 can be provided only on the outer edge portion of the sealing surface 38, which contacts the seat surface 35 when the suction valve 31 closes the suction port 32.

[0028] use Figure 5 The mold 42 shown is used to mold the valve body 31b. The mold 42 includes a molding surface 42a for molding. The protrusions 41 of the valve body 31b are formed by transferring the shape of the molding surface 42a of the mold 42. That is, when the valve body 31b is molded using the mold 42 that molds the valve body 31b into the desired shape, the protrusions 41 are formed by performing molding on the sealing surface 38. The surface shape of the protrusions 41 formed by molding is, for example, a leather texture, a wood texture, a rock grain texture, a sand texture, a satin texture, or a geometric texture.

[0029] like Figure 1 As shown, the suction through-hole 32 is a hole extending through the valve retainer 8 to communicate the pump chamber 12 with the suction passage 51, which will be described later. The opening of the suction through-hole 32 on the pump chamber 12 side is opened / closed by the valve body 31b of the suction valve 31. When the valve body 31b is disengaged from the opening, the suction passage 51 is opened. When the valve body 31b closes the opening, the suction passage 51 is closed. During the stroke that increases the capacity of the pump chamber 12, the valve body 31b is disengaged from the opening. During the remaining stroke, the valve body 31b closes the opening. That is, the suction valve 31 opens the suction passage 51 (or suction through-hole 32) during the stroke that increases the capacity of the pump chamber 12, and closes the suction passage 51 (or suction through-hole 32) during the remaining stroke. The remaining stroke includes strokes that do not increase the capacity of the pump chamber 12, and includes strokes that decrease the capacity of the pump chamber 12 and strokes that maintain the capacity.

[0030] The suction passage 51 is formed by the following: a suction fluid chamber 52, to which a suction through-hole 32 leads; a drive mechanism storage chamber 53 in the housing 3, which is connected to the suction fluid chamber 52 via a communication path (not shown); and an inlet passage 54 extending from the drive mechanism storage chamber 53 through the valve retainer 8 and the cover 9. The suction fluid chamber 52 is formed between the valve retainer 8 and the cover 9. The drive mechanism storage chamber 53 is a space for storing the drive mechanism 21. The inlet passage 54 is formed by a through-hole 56 and a through-hole 58, the through-hole 56 being formed in the valve retainer 8 and the through-hole 58 including a hollow portion of a suction tube 57 disposed in the cover 9.

[0031] The discharge through-hole 33 is a hole extending through the valve holder 8 to communicate the pump chamber 12 and a discharge passage 61. The discharge passage 61 is formed of a discharge fluid chamber 62 formed at the center between the valve holder 8 and the cap 9, and a discharge pipe 63 protruding at the axial portion of the cap 9.

[0032] In the discharge passage 61, a discharge valve 64 is attached to the valve holder 8. The discharge valve 64 has a so-called cap shape and is made of a rubber material. The discharge valve 64 includes a valve body 65 having a ring-shaped plate shape and opening / closing an opening of the discharge through-hole 33, and is fitted on a protruding portion 66 of the valve holder 8 and fixed to the valve holder 8.

[0033] The opening of the discharge through-hole 33 at the discharge fluid chamber 62 side is opened / closed by the valve body 65 of the discharge valve 64. When the valve body 65 is separated from the opening, the discharge passage 61 is opened. When the valve body 65 closes the opening, the discharge passage 61 is closed. In the stroke of reducing the capacity of the pump chamber 12, the valve body 65 is separated from the opening. In the remaining stroke, the valve body 65 closes the opening. That is, the discharge valve 64 opens the discharge passage 61 (or the discharge through-hole 33) in the stroke of reducing the capacity of the pump chamber 12, and closes the discharge passage 61 (or the discharge through-hole 33) in the remaining stroke. The remaining stroke is a stroke of not reducing the capacity of the pump chamber 12, and includes a stroke of increasing the capacity of the pump chamber 12 and a stroke of maintaining the capacity.

[0034] In the discharge stroke in which the discharge valve 64 is opened and the air in the pump chamber 12 is discharged to the discharge passage 61, the valve body 31b of the suction valve 31 is pressed against the seat surface 35 by the pressure in the pump chamber 12. At this time, the sealing surface 38 of the valve body 31b is in contact with the seat surface 35. The minute passage 36 is formed on the sealing surface 38.

[0035] In the discharge stroke in which the capacity of the pump chamber 12 is reduced, if the rising speed of the pressure in the pump chamber 12 is relatively high, that is, if the rotation speed of the motor 2 is relatively high, the passage 36 substantially functions as a diaphragm, and the amount of air leaking from the pump chamber 12 to the suction passage 51 via the passage 36 becomes relatively small. For this reason, in this case, the discharge flow rate of the diaphragm pump 1 is a flow rate substantially corresponding to the rotation speed of the motor 2.

[0036] On the other hand, if the rotation speed of the motor 2 is relatively low, more specifically, if the rotation speed is low to the extent that the motor 2 does not stop or the rotation does not become unstable due to insufficient torque, the amount of air leaking from the pump chamber 12 to the suction passage 51 via the passage 36 in the discharge stroke increases. For this reason, when the motor 2 is caused to rotate at a minimum rotation speed which is low to the extent that the motor 2 does not stop or the rotation does not become unstable, the discharge flow rate of the diaphragm pump 1 can be reduced compared to the case where the leakage structure 37 is not provided.

[0037] The seat surface 35 that contacts or separates from the valve body 31b of the suction valve 31 is formed as a smooth surface. Therefore, the leakage structure 37 of the valve body 31b that repeatedly contacts the seat surface 35 hardly wears. The less wear means that dust generation is less, and the durability is high. In a case where a foreign matter is placed in the leakage structure 37, when the valve body 31b moves with opening / closing, the foreign matter falls from the leakage structure 37 and is thus removed. For this reason, the leakage structure 37 has high stability. Therefore, according to the present embodiment, it is possible to provide a diaphragm pump that can suppress the discharge flow to a considerably low flow, and improve the performance stability and the durability.

[0038] The leakage structure 37 according to the present embodiment is formed by the concave-convex portion 41 provided on the entire sealing surface 38 of the valve body 31b. Therefore, since air can leak from the entire area of the sealing surface 38, it is possible to further reduce the discharge flow at a low rotation speed.

[0039] The concave-convex portion 41 according to the present embodiment is a concave-convex portion formed by transferring the shape of a molding surface 42a for press molding processing, which is provided on a mold 42 for molding the valve body 31b. For this reason, it is possible to easily form the concave-convex portion 41 having a complex shape, and to easily form the concave-convex portion 41 according to the performance of the diaphragm pump 1.

[0040] (Aspects of the Invention)

[0041] According to an aspect of the present application, there is provided a diaphragm pump 1 including: a diaphragm 7 including a deformation portion 11 having a cup shape; a partition plate 8 configured to close an open portion of the deformation portion 11 and form a pump chamber 12 together with the deformation portion 11; a suction through-hole 32 extending through the partition plate 8; a suction passage 51 communicating with the pump chamber 12 via the suction through-hole 32; a discharge through-hole 33 extending through the partition plate 8; a discharge passage 61 communicating with the pump chamber 12 via the discharge through-hole 33; a drive mechanism 21 configured to convert a rotation of a motor 2 into a reciprocating motion and alternately deform the deformation portion 11 in a direction in which a capacity of the pump chamber 12 is increased and in a direction in which the capacity of the pump chamber 12 is decreased; a suction valve 31 attached to the partition plate 8 and configured to open the suction passage 51 (or the suction through-hole 32) in a stroke in which the capacity of the pump chamber 12 is increased and to close the suction passage 51 (or the suction through-hole 32) in a stroke in which the capacity is not increased; and a discharge valve 64 attached to the partition plate 8 in the discharge passage 61 and configured to open the discharge passage 61 (or the discharge through-hole 33) in a stroke in which the capacity of the pump chamber 12 is decreased and to close the discharge passage 61 (or the discharge through-hole 33) in a stroke in which the capacity is not decreased, wherein the partition plate 8 includes a seating surface 35 on a side facing the pump chamber 12, and the suction valve 31 includes a valve body 31b configured to be in contact with or separated from the seating surface 35, and the valve body 31b includes a leakage structure 37 configured to form a passage 36 between the valve body 31b and the seating surface 35.

[0042] When fluid leaks from the leakage structure 37 of the valve body 31b, the discharge flow rate can be suppressed to be small. In addition, even if the leakage structure 37 of the valve body 31b repeatedly comes into contact with the seating surface 35 of the partition plate 8, the leakage structure 37 is hardly worn. Furthermore, in a case where a foreign matter is placed in the leakage structure 37, when the valve body 31b moves with opening / closing, the foreign matter falls from the leakage structure 37 and is thus removed. Therefore, it is possible to provide a diaphragm pump capable of improving performance stability and durability while adopting a configuration capable of suppressing the discharge flow rate to a flow rate that is considerably low.

[0043] The valve body 31b can include a sealing surface 38 facing the seating surface 35. The leakage structure 37 can include a concavo-convex portion 41 provided on the sealing surface 38. The concavo-convex portion 41 can include an angular portion having an inclined surface and / or a valley portion.

[0044] The concave-convex portion 41 can be provided on the entire sealing surface 38. The concave-convex portion 41 can be provided only on an outer edge portion of the sealing surface 38 that comes into contact with the seating surface 35 when the suction valve 31 closes the suction through-hole 32. The concave-convex portion 41 can be provided at least on the outer edge portion of the sealing surface 38.

[0045] The concave-convex portion 41 can be a concave-convex portion formed by transferring a molding surface 42a for press molding processing provided on a mold 42 for molding the valve body 31b.

[0046] The seating surface 35 can be a smooth surface. When the seating surface 35 is formed as a smooth surface, the leakage structure 37 of the valve body 31b that repeatedly comes into contact with the seating surface 35 is less likely to be worn.

[0047] The valve body 31b of the suction valve 31 can be formed in a ring-shaped plate shape. The valve body 31b can be formed in a shape that is curved to gradually approach the seating surface 35 toward the outer edge.

Claims

1. A diaphragm pump (1), comprising: A diaphragm (7), the diaphragm including a deformed portion (11) having a cup-shaped shape; A partition (8) is configured to close the opening of the deformable portion (11) and together with the deformable portion (11) form a pump chamber (12); A suction through-hole (32) extends through the partition (8); The suction passage (51) is connected to the pump chamber (12) via the suction through hole (32); Discharge through hole (33), the discharge through hole extending through the partition (8); Discharge channel (61), which is connected to the pump chamber (12) via the discharge through hole (33); The drive mechanism (21) is configured to convert the rotation of the motor (2) into reciprocating motion and to cause the deformable portion (11) to deform alternately in the direction of increasing the capacity of the pump chamber (12) and in the direction of decreasing the capacity of the pump chamber (12); A suction valve (31) is attached to the partition (8) and is configured to open the suction passage (51) during a stroke that increases the capacity of the pump chamber (12) and close the suction passage (51) during a stroke that does not increase the capacity. as well as A discharge valve (64) is attached to the baffle (8) in the discharge passage (61) and is configured to open the discharge passage (61) during a stroke that reduces the capacity of the pump chamber (12) and close the discharge passage (61) during a stroke that does not reduce the capacity. The partition (8) includes a seat surface (35) on the side facing the pump chamber (12), and The suction valve (31) includes a valve body (31b) configured to contact or separate from the seat surface (35), and the valve body (31b) includes a leakage structure (37) configured to form a channel (36) between the valve body (31b) and the seat surface (35).

2. The diaphragm pump (1) according to claim 1, wherein, The valve body (31b) includes a sealing surface (38) facing the seat surface (35), and The leakage structure (37) includes a protrusion (41) provided on the sealing surface (38).

3. The diaphragm pump (1) according to claim 2, wherein, The uneven portion (41) is provided on the entire sealing surface (38).

4. The diaphragm pump (1) according to claim 2 or 3, wherein, The protrusion (41) is formed by transferring the shape of a molding surface (42a) for molding processing, which is disposed on a mold (42) for molding the valve body (31b).

5. The diaphragm pump (1) according to claim 1, wherein, The seat surface (35) is a smooth surface.

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