Membranpumpe

Abstract

A diaphragm pump is provided which is configured such that a center plate is less likely to deform. The diaphragm pump (1) comprises: a pump housing (10), a crank mechanism (20) fixed to the pump housing (10), and a diaphragm assembly (22) connected to the crank mechanism (20). The diaphragm assembly (22) has a diaphragm (30) and a center plate (32) which holds an inner peripheral portion (38) of the diaphragm (30). The center plate (32) has a first holding member (34) having a fitting recess (52) and a second holding member (36) having a fitting projection (58) which is press-fitted into the fitting recess (52). The center plate (32) clamps an inner peripheral portion (38) of the diaphragm (30) between the first holding member (34) and the second holding member (36). A screw (48) for fastening the center plate (32) is installed through insertion holes (54) and (60) which extend through the fitting recess (52) and (60) respectively.the fitting projection (58). The inner diameter of the fitting recess (52) and the outer diameter of the fitting projection (58) are larger than the insertion holes (54) and (60).

Description

Technical area:

[0001] The present invention relates to a diaphragm pump configured to suck and discharge a fluid by reciprocating movement of a diaphragm. Background Art:

[0002] For example, Patent Literature 1 discloses a diaphragm pump having a center plate fixed to the center of a disc-shaped diaphragm made of an elastic member such as rubber. The center plate is reciprocated by a drive mechanism such as a crank mechanism or an electromagnetic reciprocating mechanism, thereby sucking and discharging a fluid such as air or water. The center plate consists of an inner center plate and an outer center plate, which are fixed to the drive mechanism by being pressed together with a screw, with the diaphragm sandwiched between them. Note that the outer center plate has a recess in its center, and the inner center plate has a projection in its center. By fitting the projection into the recess, the center positions of the outer and inner center plates are aligned. Citation list:Patent literature:

[0003] Patent Literature 1: Japanese Patent Application Publication No. 2012-225190 Summary of the invention:Technical problem:

[0004] There are growing demands for the diaphragm pump described above to achieve higher performance and higher flow rate. One way to achieve higher performance and higher flow is to increase the diameter of the diaphragm. In such a case, it is desirable to increase the size of the center plate in proportion to the increase in diaphragm diameter. However, when the center plate is enlarged, the distance from the center position where the center plate is held by the screw to the outer peripheral end of the center plate becomes correspondingly longer, so the possibility of the center plate deforming due to a force absorbed by the diaphragm during the reciprocating movement of the center plate increases.The deformation of the center plate causes a gap to form between the inner center plate and the outer center plate, which may make it impossible to maintain the holding state of the diaphragm, resulting in the diaphragm detaching from the center plate.

[0005] Accordingly, it is an object of the present invention to provide a diaphragm pump configured so that the center plate is less likely to deform even when the center plate is increased in diameter. Solution to the problem:

[0006] The present invention provides a diaphragm pump comprising: a pump housing; a drive mechanism fixed to the pump housing; a diaphragm having an outer peripheral portion and an inner peripheral portion, the outer peripheral portion being fixed to the pump housing; a center plate connected to the drive mechanism and holding the inner peripheral portion of the diaphragm, the center plate including a first holding member having a fitting recess and a second holding member having a fitting projection press-fitted into the fitting recess, the center plate being configured to clamp the inner peripheral portion of the diaphragm between the first holding member and the second holding member, and the center plate having an insertion hole extending through the fitting recess and the fitting projection.and a fastener installed through the insertion hole to fix the diaphragm to the drive mechanism via the center plate; wherein the inner diameter of the fitting recess and the outer diameter of the fitting projection are larger than the insertion hole.

[0007] In the diaphragm pump, the first retaining member and the second retaining member of the center plate are fixed to each other by fitting the fitting recess and the fitting projection, which are larger than the insertion hole through which the fastener is installed. Therefore, it is possible to shorten the distance between the position where the first and second retaining members are fixed to each other and the outer peripheral end of the center plate. Consequently, it is possible to reduce the likelihood of the first retaining member and the second retaining member of the center plate deforming even when the first retaining member and the second retaining member receive a force from the diaphragm in a direction away from each other during pump operation.In particular, even if the diameter of the center plate is increased, the occurrence of distortion during pump operation can be prevented by appropriately increasing the diameter of the fitting recess and the fitting projection.

[0008] Furthermore, the arrangement may be configured as follows. Not the entire outer peripheral surface of the fitting projection abuts against the inner peripheral surface of the fitting recess, so that a receiving space is formed between the inner peripheral surface of the fitting recess and the outer peripheral surface of the fitting projection. More specifically, the arrangement may be such that the fitting projection has a radially inward hollow portion, so that the receiving space is formed by the hollow portion. Even more specifically, the arrangement may be such that the fitting projection has a plurality of hollow portions equally spaced in a circumferential direction, thereby forming a plurality of radially outward projecting portions, and only outer peripheral surfaces of the plurality of projecting portions engage with the inner peripheral surface of the fitting recess.

[0009] By providing the receiving spaces between the inner peripheral surface of the fitting recess and the outer peripheral surface of the fitting projection, deformed portions of the fitting recess and the fitting projection, which are generated when the fitting projection is press-fitted into the fitting recess, can enter the receiving spaces. Consequently, it is possible to fix the first retaining member and the second retaining member to each other by firmly joining the fitting recess and the fitting projection, and at the same time, it is possible to prevent the occurrence of warpage or other undesirable deformation of the first and second retaining members due to excessive stress that would otherwise be generated in other portions of the first and second retaining members when they are assembled.

[0010] Embodiments of a diaphragm pump according to the present invention are explained below with reference to the accompanying drawings. Short description of the drawings: Fig. 1 is a perspective view of a diaphragm pump according to an embodiment of the present invention. Fig. 2 is a sectional view of the diaphragm pump from Fig. 1, along the center position of a membrane. Fig. is a cross-sectional view of a membrane arrangement. Fig. 4 is a perspective view of a top surface of a first support member of a center plate. Fig. 5 is a perspective view of a bottom side of a second support member of the center plate. Fig. 6 is a sectional view along the line AA in Fig. 3. Description of embodiments:

[0011] As in Fig. 1, a diaphragm pump 1 according to an embodiment of the present invention includes a pump housing 10 and a motor 12 mounted on the pump housing 10. The pump housing 10 is provided with a suction port 14 and a discharge port 16. The diaphragm pump 1 is configured to suck air through the suction port 14 and discharge the air through the discharge port 16 by reciprocating a diaphragm assembly 22 (described later) installed in the pump housing 10 using the motor 12. The diaphragm pump 1 is configured to be installed in a predetermined position via rubber vibration dampers 18.

[0012] As in Fig. 2, the diaphragm pump 1 further includes a crank mechanism 20 coupled to the motor 12, and a diaphragm assembly 22 attached to the crank mechanism 20. A pump chamber 24 is formed between an inner peripheral surface 10a of the pump housing 10 and the diaphragm assembly 22. A one-way valve 26 is installed between the suction port 14 and the pump chamber 24. The one-way valve 26 allows air to flow only from the suction port 14 to the pump chamber 24. Furthermore, a one-way valve 28 is installed between the pump chamber 24 and the outlet port 16. The one-way valve 28 allows air to flow only from the pump chamber 24 to the outlet port 16.The diaphragm assembly 22 is reciprocated mainly in an up-down direction by the crank mechanism 20, causing the capacity of the pump chamber 24 to increase and decrease, thus allowing air to be sucked into the pump chamber 24 via the suction port 14 and to be conveyed from the pump chamber 24 to the outlet port 16.

[0013] The membrane assembly 22 includes a disc-shaped membrane 30 and a center plate 32 that holds the membrane 30. As shown in Fig. 3, the center plate 32 has a first (lower) holding member 34 and a second (upper) holding member 36 and holds the diaphragm 30 by clamping an inner peripheral portion 38 of the diaphragm 30 between the first and second holding members 34 and 36. The diaphragm 30 has an outer peripheral locking portion 42 projecting upwardly at its outer peripheral portion 40, an inner peripheral locking portion 44 projecting downwardly at its inner peripheral portion 38, and an intermediate curved portion 46 curved upwardly at an intermediate portion. As shown in Fig. As shown in Figure 2, the outer peripheral locking portion 42 of the diaphragm 30 is fixed to the pump housing 10. Furthermore, the center plate 32 is fixed to a connecting rod 50 of the crank mechanism 20 with a screw (locking element) 48.

[0014] As in Fig. 4, the first holding member 34 of the center plate 32 has a circular fitting recess 52 in a top surface 34a thereof and an insertion hole 54 extending through the center position of the fitting recess 52. The first holding member 34 further has an annular locking groove 56 formed in the top surface 34a at a position outside the fitting recess 52. As shown in Fig. As shown in Fig. 5, the second retaining member 36 of the center plate 32 has a fitting projection 58 on its lower surface 36a and an insertion hole 60 extending through the center position of the fitting projection 58. The second retaining member 36 further includes two annular projections 62 formed on the lower surface 36a at corresponding positions outside the fitting projection 58. The fitting projection 58 has six radially inwardly directed hollow portions 64 equally spaced circumferentially, thereby forming six projecting portions 66. The fitting projection 58 is in the shape of a gear.

[0015] As in Fig. As shown in Fig. 3, the diaphragm assembly 22 is assembled by fitting the inner peripheral locking portion 44 of the diaphragm 30 into the annular locking groove 56 of the first holding member 34, and in this state, the fitting projection 58 of the second holding member 36 is press-fitted into the fitting recess 52 of the first holding member 34. The inner peripheral portion 38 of the diaphragm 30 is clamped between the upper surface 34a of the first holding member 34 and the lower surface 36a of the second holding member 36 to be held therebetween. In addition, the two annular projections 62 of the second holding member 36 bite into the diaphragm 30, whereby the diaphragm 30 can be held even more firmly. As shown in Fig.6, receiving spaces 68 are formed in the hollow portions 64 of the fitting projection 58 between the fitting projection 58 and the fitting recess 52. The fitting projection 58 engages an inner peripheral surface 52a of the fitting recess 52 only at an outer peripheral surface 58a of each projecting portion 66. Before assembly of the diaphragm assembly 22, the outer diameter of the fitting projection 58 is substantially equal to or slightly larger than the inner diameter of the fitting recess 52. Accordingly, when the fitting projection 58 is press-fitted into the fitting recess 52, the projecting portions 66 of the fitting projection 58 or the fitting recess 52 may be slightly deformed. However, the deformed portions can escape into the adjacent receiving spaces 68, so that excessive stress does not develop in other portions.If the receiving spaces 68 were not provided, there would be no path for the deformed portions, so that large stress might be generated in other portions, particularly in the base of the fitting projection 58 and its surroundings. This could cause the second holding member 36 to warp as a whole. In contrast, in the embodiment of the present invention, the occurrence of warp during the assembly process can be prevented due to the provision of the receiving spaces 68. It should be noted that the shape and number of the protruding portions 66 and the receiving spaces 68 can be changed as desired. Furthermore, the receiving spaces may be formed by forming radially outwardly directed hollow portions in the inner peripheral surface 52a of the fitting recess 52. Other different shapes for the receiving spaces are also conceivable.That is, any shape is usable provided that when the fitting projection 58 is press-fitted into the fitting recess 52, not all or only a part of the outer peripheral surface 58a of the fitting projection 58 engages with the inner peripheral surface 52a of the fitting recess 52 and receiving spaces are formed in other portions.

[0016] The assembled diaphragm assembly 22 is secured to the connecting rod 50 of the crank mechanism 20 with the screw 48, as described above. However, it should be noted that the first retaining element 34 and the second retaining element 36 of the center plate 32 are secured to each other by a virtually interference fit between the fitting recess 52 and the fitting projection 58.

[0017] In the diaphragm pump 1, the first holding member 34 and the second holding member 36 of the center plate 32, which holds the diaphragm 30, are integrally connected to each other not by the screw 48, but mainly by a fit between the fitting recess 52 and the fitting projection 58. The inner diameter of the fitting recess 52 and the outer diameter of the fitting projection 58 are larger than the insertion holes 54 and 60; Therefore, the distance from the inner and outer peripheral surfaces 52a and 58a of the fitting recess 52 and the fitting projection 58, which are fitted to each other, to an outer peripheral end 32a of the center plate 32 is shorter than the distance from the screw 48 to the outer peripheral end 32a of the center plate 32. During pump operation, an outer peripheral portion 70 of the second holding member 36 of the center plate 32 is subjected to a force of the diaphragm 30 in a direction away from the first holding member 34.However, since the distance from the outer peripheral surface 58a of the fitting projection 58, where the second holding member 36 is fixed to the first holding member 34, to the outer peripheral end 32a thereof has been shortened, the second holding member 36 is less likely to warp compared to a case where the first holding member 34 and the second holding member 36 are fixed to each other only with the screw 48. Furthermore, since the fitting recess 52 and the fitting projection 58 are fitted to each other, the first holding member 34 and the second holding member 36 are prevented from rotating relative to each other.This can prevent an undesirable force from being exerted on the diaphragm 30, which would otherwise be caused by the rotation of the second holding element 36 when tightening the screw 48, and it can also prevent the screw 48 from becoming loose during pump operation, which could otherwise be caused by the rotation of the second holding element 36.

[0018] Although some embodiments of the present invention have been described above, the present invention is not limited to these embodiments. For example, the first support member of the center plate may be formed as a component integrated with the connecting rod of the crank mechanism. Moreover, the second support member of the center plate may be fixed to the crank mechanism, and the first support member may be fixed to the second support member. In other words, the fitting protrusion may be formed on the connecting rod-side member, and the fitting recess may be formed in the other member. Although a structure including a motor and a crank mechanism is adopted as the drive mechanism in the above embodiment, other mechanisms, for example, an electromagnetic reciprocating mechanism, may be used.Furthermore, the fluid to be pumped is not limited to air, but can also be a liquid, such as water. List of reference symbols: 1 diaphragm pump 10 pump housing 10a inner circumferential surface 12 Engine 14 Suction connection 16 Outlet connection 18 rubber vibration dampers 20 Crank mechanism 22 Membrane arrangement 24 Pump chamber 26 One-way valve 28 One-way valve 30 membrane 32 center plate 32a outer circumferential end 34 first holding member 34a top 36 second holding element 36a bottom 38 inner circumferential section 40 outer peripheral section 42 outer peripheral locking section 44 inner circumferential locking section 46 intermediate curved section 48 Screw (locking element) 50 connecting rod 52 Pass recess 52a inner peripheral surface 54 insertion hole 56 annular locking groove 58 pass advantage 58a outer peripheral surface 60 insertion hole 62 annular projections 64 hollow parts 66 protruding parts 68 recording rooms 70 outer peripheral section QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] JP 2012-225190

[0003]

Claims

[1] Diaphragm pump comprising: a pump housing; a drive mechanism attached to the pump housing; a diaphragm having an outer peripheral portion and an inner peripheral portion, the outer peripheral portion being fixed to the pump housing; a center plate connected to the drive mechanism and holding the inner peripheral portion of the diaphragm, the center plate including a first holding member having a fitting recess and a second holding member having a fitting projection press-fitted into the fitting recess, the center plate being configured to clamp the inner peripheral portion of the diaphragm between the first holding member and the second holding member, and the center plate including an insertion hole extending through the fitting recess and the fitting projection; and a fastener installed through the insertion hole to fix the diaphragm to the drive mechanism via the center plate; wherein an inner diameter of the fitting recess and an outer diameter of the fitting projection are larger than the insertion hole. [2] A diaphragm pump according to claim 1, wherein not all of the outer peripheral surface of the fitting projection is engaged with an inner peripheral surface of the fitting recess, so that a receiving space is formed between the inner peripheral surface of the fitting recess and the outer peripheral surface of the fitting projection. [3] A diaphragm pump according to claim 2, wherein the fitting projection has a radially inwardly directed hollow portion so that the receiving space is formed by the hollow portion. [4] A diaphragm pump according to claim 3, wherein the fitting projection has a plurality of hollow portions equally spaced circumferentially to form a plurality of radially outwardly projecting portions, and only the outer peripheral surfaces of the plurality of projecting portions engage the inner peripheral surface of the fitting recess.

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