Diaphragm pump

Abstract

To provide a diaphragm pump having high reliability and safety.SOLUTION: In a pump body (2), an access opening (20) to a pilot chamber (17) is defined, which can be closed by a closure element (21) that can be removably fixed to the pump body (2). The closure element (21) comprises a main body (22) made of plastic material by molding, and at least one plate-shaped element (23) that defines at least a portion of a contact face of the closure element (21) and is made of a material having, with respect to a sliding pad (15), a higher wear resistance and a lower friction coefficient than the plastic material.SELECTED DRAWING: Figure 7

Description

[Technical field]

[0001] The present invention relates to a diaphragm pump. [Background technology]

[0002] Diaphragm pumps are known that have a pump body defining at least a pair of pumping chambers therein, both of which are connected to suction and delivery connectors of the pump with respective check valves interposed therebetween.

[0003] The pumping chambers are bounded by respective diaphragms which separate the pumping chambers from the respective working chambers, and compressed air is cyclically introduced and exhausted to generate alternating movement of the two diaphragms, thereby transferring the pumped liquid from the suction connector to the delivery connector of the pump.

[0004] A powered valve is provided for moving compressed air in and out of the working chambers, and cyclically connects one of the two working chambers with a source of compressed air and the other working chamber with the external environment.

[0005] The working chamber is provided inside the powered valve, and a shuttle-type flow control element is movable in a reciprocating motion, allowing alternate opening and closing of the connection of the working chamber to the compressed air source and the external environment, respectively, depending on the position it assumes.

[0006] The operation of the shuttle-type flow control element in the powered valve is controlled by a pilot valve, also called an end-of-travel valve, whose function is to admit compressed air into and expel compressed air from a portion of the working chamber of the powered valve so as to generate reciprocating motion of the shuttle-type flow control element.

[0007] In particular, the pilot valve is housed in a pilot chamber supplied with compressed air, has a sliding pad cursor therein capable of sliding along the wall of the body of the pump, and defines several ports, namely a pilot port connected to a portion of the working chamber of the power valve, and a discharge port for compressed air connected to the external environment.

[0008] More specifically, the sliding pad cursor is pushed by the diaphragm by means of a connecting rod or shaft, so that the alternating movement of the diaphragm is converted into a reciprocating movement of the pad cursor between two extreme stroke limit positions to allow compressed air to be alternately sent to the pilot port or the exhaust port, thus producing a displacement of the shuttle flow control element in one or the other direction, and thus the introduction of compressed air into one working chamber and the flushing of the other chamber, and vice versa.

[0009] Pilot valves constructed in this manner provide excellent reliability, however the sliding pads exhibit wear over time.

[0010] In prior art pumps, if an operation needs to be performed on the pilot valve, the pump must be almost completely dismantled, with obvious inconveniences in terms of both time and effort as well as cost.

[0011] To overcome this drawback, diaphragm pumps have been offered on the market that are equipped with pilot valves having sliding pads that are easily accessible from the outside of the pump.

[0012] In particular, in this case, an easily accessible region of the pump body is defined with an access opening which, under normal operating conditions of the pump, is closed by a removable closure element.

[0013] When the closure element is removed, this access opening connects the external environment with the part of the pump affected by the presence of the sliding pad, i.e. the working chamber of the pilot valve, allowing the user to easily reach the sliding pad and replace it.

[0014] Currently, the closure element of the access opening to the pilot valve is a metal body, in particular a body made of stainless steel, having a part that can be inserted into the access opening and is made from a solid block by turning using a machine tool and is fitted with an adapted gasket seal, and a flanged fixing head is designed to be fixed to the body of the pump by means of screws and is made using laser cutting or a machining center.

[0015] The pilot port and the exhaust port are also formed, again using a machine tool, in the body of the closure element on the surface intended to come into contact with the sliding pad, and corresponding portions of the channels are also formed on this surface, carrying the compressed air to the power valve and to the external environment, respectively.

[0016] Although this type of pump is from a practical point of view a sound implementation solution, pumps constructed in this way prove to be rather complicated to manufacture and have very high manufacturing costs.

[0017] Another drawback of the known technology is constituted by the fact that currently dust, dirt, liquids, etc. tend to enter the working chamber of the pilot valve through the exhaust port, which can cause serious problems in the operation of the pump. Summary of the Invention [Problem to be solved by the invention]

[0018] It is an object of the present invention to provide a diaphragm pump that is able to improve upon the known art in one or more of the above mentioned aspects. [Means for solving the problem]

[0019] Within this objective, it is an object of the present invention to provide a diaphragm pump which allows convenient access to the inner area of ​​the pilot valve without the need for disassembly of the pump and which at the same time can be provided simply and at low cost.

[0020] Another object of the invention is to provide a diaphragm pump which allows optimal and rational use of materials for its manufacture.

[0021] Another object of the present invention is to provide a diaphragm pump which can prevent the possibility of dust or dirt entering the interior of the pilot valve through the exhaust port of the pilot valve.

[0022] A further object of the present invention is to overcome the drawbacks of the known art in an alternative manner to any existing solutions.

[0023] Another object of the present invention is to provide a diaphragm pump which offers high reliability and safety in its operation.

[0024] This object, as well as these and other objects which will become more apparent hereinafter, are achieved by a diaphragm pump according to claim 1, optionally comprising one or more of the features of the dependent claims.

[0025] Further features and advantages of the present invention will become more apparent from the following detailed description of preferred, but not exclusive, embodiments of a diaphragm pump according to the invention, illustrated by way of non-limiting example in the accompanying drawings, in which: [Brief description of the drawings]

[0026] [Figure 1] FIG. 1 is a perspective view of a diaphragm pump according to the present invention. [Diagram 2] FIG. 1 is an exploded perspective view of a pump according to the present invention, with parts omitted for simplicity. [Diagram 3] FIG. 3 is a perspective view of a portion of the pump of FIG. 2. [Figure 4]FIG. 1 is a perspective view of a pump according to the present invention, partially cut away to show the interior. [Diagram 5] FIG. 2 is a plan view from above of a portion of a pump according to the present invention; [Figure 6] FIG. 6 is a cross-sectional view taken along line VI-VI of FIG. 5. [Figure 7] FIG. 7 is a cross-sectional view taken along line VII-VII in FIG. 5. [Figure 8] 1 is an exploded perspective view of a closure element for an access opening to a pilot valve of a pump according to the invention; FIG. [Figure 9] FIG. 2 is a side view of the closure element. [Figure 10] 10 is a cross-sectional view of the closure element taken along line XX in FIG. 9. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0027] With reference to the figures, a diaphragm pump according to the invention, generally designated by reference numeral 1, comprises a pump body 2 defining therein at least a pair of pumping chambers 3 and 4 which are connected at an inlet to at least one suction connector 5 and at an outlet to at least one delivery connector 6 of the pump, by the interposition of respective non-return valves 3a, 3b and 4a, 4b.

[0028] In particular, the pumping chambers 3 and 4 are defined by respective diaphragms 7 and 8 which separate the pumping chambers 3 and 4 from the respective working chambers, more precisely from a first working chamber 9 and a second working chamber 10 .

[0029] More specifically, as known per se, the working chambers 9 and 10 can be alternately connected to a compressed air source 200 , advantageously by means of a powered valve 11 associated with the pump body 2 .

[0030] The powered valve 11 allows compressed air to be cyclically sent to one of the two working chambers 9, 10 while the compressed air present in the other working chamber 9, 10 is exhausted to the external environment and vice versa, imparting a simultaneous reciprocating motion to the two diaphragms 7 and 8, thereby allowing the volume of the pumping chambers 3 and 4 to be varied, resulting in the transfer of the liquid to be pumped from the suction connector 5 to the delivery connector 6.

[0031] Advantageously, as known per se, a working chamber 12 is provided inside the powered valve 11, in which a flow control element of the shuttle type 13 can move in a reciprocating motion, allowing alternate opening and closing of the connections of the working chambers 9 and 10 with the compressed air source 200 and with the external environment, respectively, depending on the position assumed within the working chamber 12.

[0032] In particular, the shuttle-type flow control element 13 can be moved within the working chamber 12 between a first operating position in which compressed air is routed to the first working chamber 9 and exhausted from the second working chamber 10, and a second operating position in which compressed air is routed to the second working chamber 10 and exhausted from the first working chamber 9.

[0033] The powered valve 11 is controlled by a pilot valve 14, which is conveniently also defined within the pump body 2 together with its valve body.

[0034] The pilot valve 14 in particular makes it possible to command the displacement of the shuttle-type flow control element 13 of the powered valve 11 from a first operating position to a second operating position, and vice versa, by delivering compressed air to at least a portion of the working chamber 12 of the powered valve 11, as described below.

[0035] In detail, as in the illustrated example, the shuttle-type flow control element 13 of the powered valve 11 has a rod portion 13a that occupies less lateral space than the working chamber 12, the rod portion 13a extends axially within the working chamber 12 and is connected at one end to a plunger portion 13b that slides along the side wall of the working chamber 12 and is configured to divide the working chamber 12 into a first portion 12a that is always connected to the compressed air source 200 and through which the rod portion 13a extends, and a second portion 12b that is connected to a pilot valve 14 that operates to alternately connect the second portion 12b of the working chamber 12 to the compressed air source 200 or to the external environment.

[0036] More specifically, the surface of the plunger portion 13b facing the first working portion 12a of the working chamber 12 is smaller than the surface of the plunger portion 13b facing the second working portion 12b of the working chamber 12.

[0037] In this way, when the pilot valve 14 connects the second part 12b of the working chamber 12 with the external environment, the plunger part 13a automatically assumes one of two operating positions, for example the first operating position, under the thrust exerted by the compressed air present in the first part 12a of the working chamber 12.

[0038] Instead, when the pilot valve 14 connects the second part 12b of the working chamber 12 with the compressed air source 200, the thrust exerted on the plunger part 13b by the compressed air present in the second part 12b of the working chamber 12 is greater than the thrust exerted on the plunger part 13b by the compressed air present in the first part 12a of the working chamber 12, displacing the shuttle-type flow control element 13 towards the other operating position, i.e. the second operating position, since the surface of the plunger part 13b facing towards the second part 12b of the working chamber 12 is greater compared to the surface of the same plunger part 13b facing towards the first part 12a of the working chamber 12.

[0039] In detail, the pilot valve 14 has a pilot chamber 17 to which compressed air is supplied and in which a sliding pad 15 capable of moving in a reciprocating motion is housed, and alternately connects this pilot chamber 17 to a pilot port 18 connected to the pilot valve 11, more specifically, to the second part 12b of the working chamber 12 of the power valve 11, or to an exhaust port 19 connected to the external environment.

[0040] The sliding pad 15 is mechanically pressed by the diaphragms 7 and 8 , expediently by means of a connecting rod 16 , so that its position in the pilot chamber 17 is determined by the positions of the diaphragms 7 and 8 .

[0041] Furthermore, the pump body 2 is provided with an access opening 20 adapted to allow access to the pilot chamber 17 and the sliding pad 15 from the outside in order to carry out maintenance work on the pilot valve 14 .

[0042] Conveniently, such access opening 20 is defined in an area of ​​the pump body which is easily and conveniently accessible to an operator, in particular in a flat surface defined in the upper portion of the pump body 2 .

[0043] The access opening 20 is closed, in normal operating conditions of the pump, by a closure element 21 which can be removably fixed to the pump body 2 .

[0044] The closure element 21 can be inserted into the access opening 20 and has a contact surface 21 a adapted to come into contact with the sliding pad 15 .

[0045] In particular, both the pilot port 18 and the exhaust port 19 are defined in the contact surface 21 a of the closure element 21 .

[0046] The closure element 21 is made by casting and comprises a body 22 made of plastic material and at least one plate-like element 23 which is joined to the body 23 and defines at least a part of the contact surface 21a of the closure element 21, more precisely the part of the contact surface 21a which is influenced by the sliding pad 15 sliding thereon.

[0047] Such plate-like elements 23 are made of a material that is more wear-resistant and has a lower coefficient of friction with respect to the plastic material from which the body 22 is made than the sliding pads 15 .

[0048] For example, the material constituting the plate-like elements 23 can be a metallic material, preferably stainless steel, or a ceramic material.

[0049] The plastic material that may be actively used to construct the body 22 may be, for example, polypropylene.

[0050] As shown, the plate-like element 23 advantageously has holes defining the pilot port 18 and the exhaust port 19 of the pilot valve 14, respectively.

[0051] In particular, such holes are arranged in the plate-like element 23 so as to align with the pilot channel 24 and the exhaust channel 25 defined within the body 22 of the closure element 21, respectively, once the plate-like element 23 is joined to the body 22 of the closure element 21.

[0052] Advantageously, a pilot channel 24, in which the closure element 21 is arranged in the access opening 20, is defined in the pump body 2 and is connected to a connection 26 leading to the second part 12b of the working chamber 12 of the power valve 11, while the exhaust channel 25 is connected directly to the outside, as described below.

[0053] Advantageously, at least one gasket 27 is interposed between the body 22 of the closure element 21 and the plate-shaped element 23, which is configured to ensure, in addition to a fluid seal between the pilot channel 24 and the exhaust channel 25, continuity between the hole defining the pilot port 18 and the pilot channel 24, and between the hole defining the exhaust port 19 and the exhaust channel 25.

[0054] For example, gasket 27 has an annular portion 27a designed to engage with the areas of plate-like element 23 and body 22 extending around the holes defining pilot port 18 and exhaust port 19, and a central portion 27b disposed within annular portion 27a, with its ends connected to two opposite points of annular portion 27a, and designed to be interposed between the holes of pilot port 18 and exhaust port 19.

[0055] Advantageously, an accommodating recess 28 is defined in the body 22 and contoured to enable the plate-like element 23 to be placed therein, so that the plate-like element 23, with its face arranged on the contact surface 21a of the closure element 21, is arranged substantially flush with the part of the body of the closure element arranged on the contact surface 21a of the closure element 21.

[0056] Advantageously, the body 22 of the closure element 21 is provided along its extension axis 100 with a connecting portion 22a which is contoured to substantially correspond to the access opening 20 and which can be axially inserted into the interior of the access opening with one of its ends at which the contact surface 21a of the closure element 21 is located.

[0057] At an end opposite the insertion portion 22 a , the body 22 further includes a fastening head 22 b projecting laterally relative to the coupling portion 22 a for engaging a region of the pump body disposed about the access opening 20 .

[0058] Advantageously, a receiving opening 29 is defined in the fixing head 22 b for a fixing screw 30 which can be screwed into the pump body 2 so that the closure element 21 can be fixed to the pump body 2 .

[0059] For example, as in the illustrated embodiment, the fixation head 22b may include a pair of lateral projections or wings that are opposed to one another and project radially relative to the extension axis 100 of the body 22, each of which defines a respective receiving opening 29 for the fixation screw 30.

[0060] Advantageously, the recessed area 32 is defined in the pump body 2 in the flat surface in which the access opening 20 is located, is located around the access opening 20 and is contoured to receive the fixing head 22b, so that when the closure element 21 is positioned in the access opening 20, the fixing head 22b is recessed into the pump body 2 with its surface facing outward in a position aligned with the flat surface of the pump body 2 in which the access opening 20 is defined.

[0061] Advantageously, it should be noted that the compressed air discharge channel 25 defined inside the body 22 of the closure element 21 is connected to the external environment at at least one outlet opening 33 defined in a part of the body 22 adapted to be placed outside the pump body 2 and is in a transverse position with respect to the extension axis 100 of the body 22 so as to prevent or at least significantly limit the risk of dust or other dirt entering the pilot chamber 17 of the pilot valve 14 through the discharge channel 25.

[0062] Conveniently, the outlet opening 33 can be defined on the side of a substantially cylindrically shaped axial protrusion 34 which is integrally defined in the body 22 of the closure element 21 and protrudes axially from the face of the fixing head 22b which is designed to remain outside the pump body 2 when the closure element 21 is positioned in the access opening 20.

[0063] Advantageously, as in the illustrated example, the exhaust channel 25 extends starting from the exhaust port 19 towards the outlet opening 33, for at least one first portion, substantially parallel or, optionally, coaxial with the extension axis 100, and for at least one second portion, connected to the first portion and extending substantially radially with respect to the first portion.

[0064] Basically, the discharge channel 25 may advantageously be L-shaped. The pilot channel 24 is then provided with a connection port 35 on the side of the connecting portion 22a of the body 22 of the closure element 21, which is consequently aligned with the connection portion 26 when the closure element 21 is positioned within the access opening 20, thereby obtaining communication between the pilot port 18 and the second portion 12b of the working chamber 12 of the powered valve 11.

[0065] For the sake of completeness, it should be noted that, in order to ensure sealing of the pilot chamber 17 when the closure element 21 is positioned within the access opening 20, one or more sealing elements 36 are advantageously associated with the body 22 of the closure element 21 and designed to act between the coupling portion 22a of the body 22 and the side wall of the access opening 20.

[0066] Such sealing element 36 advantageously comprises a sealing ring extending around the extension axis 100 and housed in a respective annular groove 37 defined in a side of the coupling portion 22a of the body 22 of the closure element 21.

[0067] In particular, the sealing elements 36 are arranged along the coupling portion 22 a such that they are arranged on opposite sides to a connection port 35 of the pilot channel 24 so as to also ensure sealing of the connection between the pilot channel 24 and the connection portion 26 .

[0068] The use of the diaphragm pump according to the invention is as follows. Under normal operating conditions of the pump, the closure element 21 is positioned in the access opening 20 so as to close the connection between the pilot chamber 17 of the pilot valve 14 and the external environment and is fixed to the pump body 2 by means of a fixing screw 30.

[0069] In these conditions, the compressed air supplied by the compressed air source 200 to the first part 12a of the working chamber 12 of the powered valve 11 is alternately sent to one or the other of the two working chambers 9 and 10, depending on the position in which the shuttle-type flow control element 13 is located, causing a simultaneous displacement of the diaphragms 7 and 8 and thus a change in the volume of the corresponding pumping chambers 3 and 4, resulting in the transfer of the liquid to be pumped from the suction connector 5 to the delivery connector 6 of the pump.

[0070] The movement of the shuttle-type flow control element 13 from the first operating position to the second operating position 13 is obtained by alternate delivery and flushing of compressed air by the second part 12b of the working chamber 12 of the power valve 11 based on the position assumed by the sliding pad 15 in the pilot chamber 17 of the pilot valve 14.

[0071] In particular, when the diaphragms 7 and 8 reach one of their stroke limit positions, the sliding pad 15 is in a position where it either opens the connection between the pilot port 18 and the first part 12a of the working chamber 12 of the power valve 11, or opens the connection between the second part 12b of the working chamber 12 of the power valve 11 and the external environment, thereby causing a displacement of the shuttle-type flow control element 13 from one of its operating positions to the other, thus sending compressed air into the previously flushed working chambers 9, 10, and obtaining another change in the volume of the respective pumping chambers 3 and 4 as a result of the reversal of the movement of the diaphragms 7 and 8 towards their other stroke limit positions.

[0072] If intervention is required for maintenance or repair of the pilot valve 14, it is not necessary for the operator to carry out a complete disassembly of the pump body 2; it is sufficient for the operator to unscrew the fixing screw 30 from the pump body 2 and remove the closure element 21, reach the interior of the pilot valve 14 via the access opening 20 and carry out the required intervention without difficulty.

[0073] From the above, it can be seen that the present invention fully achieves its intended aims and objectives by providing a diaphragm pump, the closure element of the opening allowing easy access to the inner area of ​​the pilot valve, is obtained using technologies and materials which are able to optimally combine the requirements of reliability and safety of the components with the requirements of simplicity and economy of construction.

[0074] The invention thus conceived is susceptible to numerous modifications and variations, all of which are within the scope of the appended claims. Moreover, all the details may be substituted by other technically equivalent elements.

[0075] In fact, the materials used can be any, depending on the requirements and the state of the art, as long as they fit the specific application, as well as the conditional dimensions and shapes.

Claims

1. A diaphragm pump comprising a pump body (2) defining therein at least a pair of pumping chambers (3, 4) connected at an inlet to at least one suction connector (5) and at an outlet to at least one delivery connector (6) of the pump via respective check valves (3 a, 3 b, 4 a, 4 b), said pumping chambers (3, 4) being separated by respective diaphragms (7, 8) separating said pumping chambers (3, 4) from respective working chambers (9, 10), each of which can be alternatively connected to a compressed air source (200) by means of a powered valve (11) controlled by a pilot valve (14) comprising a sliding pad (15) mechanically pressed by said diaphragms (7, 8) and able to move in a reciprocating motion within said pilot chamber (17) supplied with compressed air, in order to alternatively connect said pilot chamber (17) to a pilot port (18) connected to said powered valve (11) or to an exhaust port (19) connected to the external environment, 1. A pump comprising: in said pump body (2) there is an access opening (20) configured to allow access from the outside to said pilot chamber (17) and to said sliding pads (15), said access opening (20) being closable by a closure element (21) that can be removably fixed to said pump body (2), said closure element (21) being insertable into said access opening (20) and having a contact surface (21 a) designed to come into contact with said sliding pads (15), said pilot port (18) and said discharge port (19) being defined in said contact surface (21 a), said closure element (21) comprising a body (22) made of a moulded and plastic material and at least one plate-like element (23) connected to said body (22) and defining at least one part of said contact surface (21 a), said plate-like element (23) being made of a material having a higher wear resistance and a lower coefficient of friction with respect to said sliding pads (15) than said plastic material.

2. 2. The pump according to claim 1, characterized in that the plate-like element (15) has holes defining the pilot port (18) and the exhaust port (19), respectively, which holes can be aligned with pilot channels (24) and exhaust channels (25), respectively, defined inside the body (22), when the plate-like element (23) is coupled to the body (22), and at least one gasket (27) is interposed between the body (22) and the plate-like element (23).

3. 2. A pump according to claim 1, characterized in that a receiving recess (28) for said plate-shaped element (23) is defined in said body (22).

4. 10. A pump according to claim 9, characterized in that the body (22) is substantially shaped along its extension axis (100) to correspond to the access opening (20) and has at one of its ends a connecting portion (22a) which can be axially inserted into the access opening (20), and a fixing head (22b) arranged at the opposite end to the connecting portion (22a), projecting laterally relative to the connecting portion (22a) and engaging in a region of the pump body (22) arranged around the access opening (20), the fixing head having a receiving opening (29) for a fixing screw (30).

5. 10. A pump according to any one of the preceding claims, characterised in that a recessed area (32) adapted to receive the fixing head (22b) is defined in the pump body (2).

6. 10. The pump according to claim 1, characterized in that the discharge channel (25) is connected with the external environment by at least one outlet opening (33), the outlet opening being defined in a part of the body (22) designed to be placed outside the pump body (2), the outlet opening (33) being arranged transversely with respect to the extension axis (100) of the body (22).

7. 10. The pump according to claim 1, characterized in that the discharge channel (25) extends, starting from the discharge port (19) towards the outlet opening (33), for at least one first portion substantially parallel to the extension axis (100) and for at least one second portion connected to the first portion and extending substantially radially with respect to the first portion.

8. 10. A pump according to any one of the preceding claims, characterized in that the material from which the plate-like elements (23) are made is a metallic or ceramic material.

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