Series-parallel two-stage vacuum diaphragm pump

Abstract

The series-parallel two-stage vacuum diaphragm pump comprises a double-output-shaft motor, and the two output ends of the double-output-shaft motor are each connected with a single-head diaphragm pump. The single-head diaphragm pump comprises a head cover, a valve plate, a pump shell, a diaphragm and a connecting rod assembly. An inlet pipe and an outlet pipe are arranged on the head cover; the upper end face of the valve plate is tightly and hermetically connected with the head cover, and an inlet cavity, an outlet cavity and a difference compensation cavity which are mutually independent are formed; after the lower end face of the valve plate is tightly and hermetically connected with the pump shell, the edge of the diaphragm is pressed and fixed by the valve plate and the pump shell, and a closed diaphragm cavity is formed; the inlet cavity, the outlet cavity and the difference compensation cavity are all communicated with the closed diaphragm cavity; the connecting rod assembly is driven by the output end to be used for driving the diaphragm to do reciprocating motion. And the compensation channel is communicated with the difference compensation cavities of the two single-head diaphragm pumps. According to the structure combining the advantages of series connection and parallel connection, opening and closing of the vacuum valves are controlled through pressure difference, and the large-flow and high-vacuum requirements are met. And meanwhile, the vacuum degree is further improved by optimally designing a closed diaphragm cavity.

Description

Technical Field

[0001] The present invention relates to the field of vacuum pumps, in particular to a series-parallel two-stage vacuum diaphragm pump. Background Art

[0002] A vacuum diaphragm pump is a positive displacement vacuum pump that uses the reciprocating motion of a diaphragm to compress and discharge gas. It is a type of oil-free dry pump. The operating principle of a vacuum diaphragm pump is based on the reciprocating motion of the diaphragm. When the motor drives the diaphragm up and down, the volume of the pump chamber changes accordingly, thereby allowing gas to be drawn in and out. Due to their high efficiency, oil-free operation, and corrosion resistance, vacuum diaphragm pumps are widely used in various fields.

[0003] Among existing vacuum diaphragm pump designs, one type uses a dual-output shaft motor to synchronously drive two diaphragm pumps, which generally include a series type and a parallel type.

[0004] Series type can refer to Figure 12 The series structure uses air pipes to connect the inlet and outlet ends of the head cover in series. The advantage of the series structure is its simple structure, but the disadvantages are: (1) at the same speed and stroke, the series structure can only achieve half the high vacuum flow rate of the parallel structure, which cannot meet the flow requirements; (2) limited by the motor characteristics and pump body size design, increasing the speed or redesigning the pump body is costly.

[0005] Parallel type can refer to Figure 13 The parallel type uses air pipes to connect the two independently working outlet pipes in parallel, forming a parallel air path. At the same speed and stroke, the parallel type doubles the flow rate of the series type, but the vacuum degree is only about 80%, which cannot meet the requirements of high vacuum.

[0006] At the same time, due to the limitations of top clearance and stroke, the parallel structure cannot achieve high vacuum by modification. Summary of the Invention

[0007] The present invention aims to provide a series-parallel two-stage vacuum diaphragm pump that combines the advantages of both series and parallel connections. This pump controls the opening and closing of vacuum valves by differential pressure to meet the requirements of high flow and high vacuum. Furthermore, the optimized design of the sealed diaphragm chamber further enhances the vacuum level.

[0008] The technical solution for achieving the object of the present invention is as follows: the present invention includes a dual-output shaft motor, wherein the two output ends of the dual-output shaft motor are respectively connected to a single-head diaphragm pump; the single-head diaphragm pump includes a head cover, a valve plate, a pump housing, a diaphragm, and a connecting rod assembly; the head cover is provided with an inlet pipe and an outlet pipe; the upper end surface of the valve plate is tightly and sealingly connected to the head cover, forming mutually independent inlet chamber, outlet chamber, and compensation chamber; the lower end surface of the valve plate is provided with a chamber; After the lower end surface of the valve plate is tightly and sealedly connected to the pump housing, the valve plate and the pump housing press and fix the edge of the diaphragm; a closed diaphragm cavity is formed between the diaphragm and the chamber; the inlet cavity, outlet cavity and compensation cavity are all connected to the closed diaphragm cavity; The connecting rod assembly is used to be fixedly connected to the diaphragm and is transmission-connected to the output ends of the corresponding sides of the dual-output motor shaft; the connecting rod assembly is used to drive the diaphragm to reciprocate under the drive of the output end; A first one-way valve is provided at the connection between the inlet cavity and the sealed diaphragm cavity, which only allows the medium to enter the sealed diaphragm cavity; a second one-way valve is provided at the connection between the outlet cavity and the sealed diaphragm cavity, which only allows the medium to enter the outlet cavity; It also includes a compensation channel connecting the compensation cavities of two single-head diaphragm pumps; a third one-way valve is provided at the connection between the compensation cavity of one single-head diaphragm pump and the closed diaphragm cavity on its corresponding side, which only allows the medium to enter the compensation cavity.

[0009] Furthermore, the above-mentioned connecting rod assembly includes an upper fixer, a fastening bolt, a lower fixer, a connecting rod, a bearing and an eccentric wheel; the diaphragm is located between the upper fixer and the lower fixer; the upper fixer is located on one side of the closed diaphragm cavity; the fastening bolt passes through the upper fixer, diaphragm and lower fixer in sequence from top to bottom, and is fixedly connected to the upper end of the connecting rod; the lower end of the connecting rod is provided with a bearing sleeve; the eccentric wheel is fixedly connected to the output end of the corresponding side of the dual-output shaft motor, and a bearing is sleeved on the outside of the eccentric wheel; the bearing is installed in the bearing sleeve of the connecting rod on the corresponding side; the connecting rod performs up and down reciprocating motion under the action of the driven eccentric wheel, and drives the diaphragm to perform up and down reciprocating motion.

[0010] Furthermore, a third one-way valve is provided at the connection between the compensation cavity of one single-head diaphragm pump and the closed diaphragm cavity on its corresponding side, which only allows the medium to enter the compensation cavity; a fourth one-way valve is provided at the connection between the compensation cavity of the other single-head diaphragm pump and the closed diaphragm cavity on its corresponding side, which only allows the medium to enter the closed diaphragm cavity.

[0011] Furthermore, the lower fixture includes a disc-shaped reference plate and a first connection hole provided at the center of the reference plate; the upper fixture includes a disc-shaped pressing plate and a second connection hole provided at the center of the pressing plate; the lower end surface of the pressing plate and the upper end surface of the reference plate are press-fitted and fixed to the diaphragm by fastening bolts; The outer edge of the upper surface of the reference plate forms a bearing surface that is inclined downwardly outward; the outer edge of the upper surface of the press plate forms a first inclined surface that is inclined downwardly outward; the press plate is provided with a second inclined surface in the thickness direction that is connected to the first inclined surface and inclined inwardly; The diameter of the chamber side surface gradually decreases from the lower end opening to the chamber top surface; the chamber side surface includes a naturally connected annular arc surface, a chamfered arc surface, and an annular inclined surface in sequence from the lower end opening to the chamber top surface; When the diaphragm stroke is at the upward limit position, the gap between the outer edge of the bearing surface and the annular arc surface on the side of the chamber is: 2.88~3.07mm; the gap between the inner edge of the bearing surface and the annular arc surface on the side of the chamber is: 2.59mm~2.77mm; the gap between the lower edge of the second inclined surface and the annular inclined surface on the side of the chamber is: 1.13mm~1.24mm; the gap between the junction of the second inclined surface and the first inclined surface and the annular inclined surface on the side of the chamber is: 0.86mm~1.06mm; the gap between the inner edge of the first inclined surface and the top surface of the chamber is: 0.96mm~1.06mm; the gap between the highest position of the upper fixer and the top surface of the chamber is: 0.53mm~0.73mm.

[0012] Furthermore, the two single-head diaphragm pumps are symmetrically arranged; a first circular groove, a second circular groove and a third circular groove are provided on the upper end surface of the valve plate; a fourth circular groove, a fifth circular groove and a sixth circular groove corresponding to the first circular groove, the second circular groove and the third circular groove are respectively provided on the end surface of the head cover facing the upper end surface of the valve plate; when the head cover is fastened to the valve plate, the first circular groove and the fourth circular groove cooperate to form an inlet cavity, the second circular groove and the fifth circular groove cooperate to form an outlet cavity, and the third circular groove and the sixth circular groove cooperate to form a compensation cavity; When the head cover is fastened to the valve plate, O-ring grooves are formed between the head cover and the valve plate around the outside of the inlet cavity, outlet cavity and compensation cavity. An O-ring is installed in each O-ring groove. When the head cover is fastened to the valve plate, each O-ring is deformed under pressure and forms a seal for the corresponding inlet cavity, outlet cavity or compensation cavity. The bottoms of the first circular groove, the second circular groove, and the third circular groove are all connected to the sealed diaphragm cavity through through holes; the inlet pipe is connected to the fourth circular groove through the inlet hole; and the outlet pipe is connected to the fifth circular groove through the outlet hole. Both the first circular groove and the second circular groove are provided with multiple through holes, and the number of through holes on the first circular groove is greater than the number of through holes on the second circular groove; the number of through holes on the third circular groove of one of the single-head diaphragm pumps provided with a third one-way valve plate is less than the number of through holes on the third circular groove of the other single-head diaphragm pump.

[0013] Furthermore, the first circular groove is provided with five through holes; the second circular groove is provided with four through holes; the third circular groove of the single-head diaphragm pump provided with a third one-way valve plate is provided with a through hole, and the third circular groove of the other single-head diaphragm pump is provided with three through holes.

[0014] Furthermore, the multiple through holes on the above-mentioned first circular groove are distributed in a circular array along the central axis of the first circular groove within an angular range of less than 360°; the multiple through holes on the third circular groove provided with multiple through holes are distributed in a circular array along the central axis of the third circular groove within an angular range of less than 360°.

[0015] Furthermore, the inlet hole includes two inlet holes symmetrically arranged along the central axis of the fifth circular groove; and the outlet hole includes two outlet holes symmetrically arranged along the central axis of the sixth circular groove.

[0016] Furthermore, the first circular groove, the second circular groove and the third circular groove are all arranged in the first flat area of ​​the valve plate; the fourth circular groove, the fifth circular groove and the sixth circular groove are all arranged in the second flat area of ​​the head cover.

[0017] Furthermore, the four corners of the valve plate form a valve plate connection area, and a first grid forming area is formed between the valve plate connection area and the first flat area; the four corners of the head cover form a head cover connection area, and a second grid forming area is formed between the head cover connection area and the second flat area; when the head cover is tightly connected to the valve plate, the first flat area and the second flat area correspond to each other.

[0018] Furthermore, a valve plate connection area is provided in the middle of the valve plate, and a head cover connection area is also provided in the middle of the head cover; the head cover connection area of ​​the head cover and the valve plate connection area of ​​the valve plate are fastened together by connecting bolts.

[0019] Furthermore, at least one gasket is provided between the lower fixer and the upper end of the connecting rod, through which a fastening bolt passes and which is used to adjust the distance between the lower fixer and the upper end of the connecting rod.

[0020] Furthermore, a cooling fan is fixedly provided at the output ends on both sides of the above-mentioned dual-output shaft motor; the cooling fan is located in the pump housing and rotates under the drive of the output end; the connecting rod assembly is located between the cooling fan on the corresponding side and the dual-output motor.

[0021] Furthermore, the pump housing is provided with heat dissipation holes.

[0022] Furthermore, a connecting flange is provided on the pump housing; the pump housings of the two single-head diaphragm pumps are respectively mounted on both ends of the dual-output motor; the two pump housings are fastened together by locking nuts after a long screw passes through their respective connecting flanges.

[0023] As a variant design, a third one-way valve plate is provided at the connection between the compensation chamber of one single-head diaphragm pump and the closed diaphragm chamber on its corresponding side, which only allows the medium to enter the compensation chamber; the other single-head diaphragm pump does not have a compensation chamber, and it connects the compensation channel with the closed diaphragm chamber of the single-head diaphragm pump through a valve hole.

[0024] The present invention has the following positive effects: (1) By simply changing the air inlet and outlet modes of the head cover and valve plate, the present invention can achieve the advantages of high vacuum and high flow in both series and parallel structures, without consuming a large amount of manpower, material and financial resources to re-verify the life of the entire pump, thus greatly reducing the cost of the change. Furthermore, the opening and closing of the third one-way valve plate is controlled by the pressure difference to meet the requirements of high flow and high vacuum.

[0025] (2) The present invention further improves the vacuum degree by optimizing the design of the gap between the upper and lower retainers of the fixed diaphragm and the top of the sealed diaphragm cavity during the stroke.

[0026] (3) The present invention enables parallel operation when the pressure differential is very small through the third and fourth one-way valve plates; when the pressure differential is too high, they can be opened simultaneously to achieve series operation. At the same time, because the third and fourth one-way valves are respectively used in the compensation chambers of the two single-head diaphragm pumps, they are not easily clogged and can be used as superheated steam vacuum pumps.

[0027] (4) The present invention adopts a split design for the connection between the diaphragm and the connecting rod assembly, which is convenient for assembly and subsequent maintenance, and can also facilitate the adjustment of the height of the connecting rod assembly to meet the height tolerance requirements and facilitate the adjustment of the vacuum degree.

[0028] (5) The number of through holes in the present invention can further increase the pump pressure. At the same time, the distribution of the through holes is actually offset (i.e., not evenly distributed around the circumference), which helps to open the valve plate in the presence of water or water vapor.

[0029] (6) The design of the first flat area and the second flat area in the present invention helps to control leakage and thus ensure vacuum.

[0030] (7) In the present invention, a fastening connection position is added between the head cover and the valve plate at positions corresponding to the first flat area and the second flat area, which can reduce the deformation of the head cover and the valve plate during the production and installation process, thereby further ensuring the vacuum degree.

[0031] (8) The design of the first grid forming area of ​​the valve plate and the second grid forming area of ​​the head cover in the present invention is to make the wall thickness of the parts more uniform, which is conducive to controlling the degree of deformation of the head cover and valve plate during molding, while increasing the surface area of ​​the head cover and valve plate and improving heat dissipation.

[0032] (9) The present invention can further actively dissipate heat inside the pump casing through a cooling fan.

[0033] (10) The heat dissipation holes on the pump housing of the present invention can further improve the heat dissipation effect. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] In order to make the content of the present invention more clearly understood, the present invention is further described in detail below based on specific embodiments and in conjunction with the accompanying drawings, wherein Figure 1 It is a structural schematic diagram of the present invention; Figure 2 This is a schematic diagram of the series-parallel gas paths in the present invention; Figure 3 Schematic diagram of the cross-section of the series-parallel structure in the present invention; Figure 4 A longitudinal sectional view of the present invention; Figure 5 It is a cross-sectional view of the single-head diaphragm pump of the present invention; Figure 6 Schematic diagram of the structure of the head cover in the present invention; Figure 7 This is a schematic diagram of the end faces of the two head covers facing the valve plate in the present invention; Figure 8 Schematic diagram of the structure of the valve plate in the present invention; Figure 9 is a cross-sectional view of the valve plate of the present invention; Figure 10 This is a schematic diagram of the interior of the closed diaphragm cavity of the present invention; Figure 11 Schematic cross-sectional view of the series-parallel structure in Example 2 of the present invention; Figure 12 It is a schematic diagram of the gas path of an existing series vacuum diaphragm pump; Figure 13 It is a schematic diagram of the gas path of an existing parallel vacuum diaphragm pump.

[0035] In the figure, a dual-output shaft motor 1, a single-head diaphragm pump 2, a head cover 21, a valve plate 22, a pump housing 23, a diaphragm 24, a connecting rod assembly 25, an inlet cavity 26, an outlet cavity 27, a compensation cavity 28, a closed diaphragm cavity 29, an inlet pipe 211, an outlet pipe 212, a fourth circular groove 213, a fifth circular groove 214, a sixth circular groove 215, a second flat area 216, a head cover connection area 217, a second grid forming area 218, a chamber 221, a first flat area 222, a valve plate connection area 223, a first grid forming area 224, a heat dissipation hole 231, a connecting flange 232, an upper fixer 251, a fastening bolt 252, a lower fixer 253, and a connecting rod 254, bearing 255, eccentric wheel 256, annular arc surface 221-1, chamfered arc surface 221-2, annular inclined surface 221-3, first circular groove 221-4, second circular groove 221-5, third circular groove 221-6, first inclined surface 251-1, second inclined surface 251-2, bearing surface 253-1, bearing sleeve 254-1, first one-way valve disc 261, second one-way valve disc 271, third one-way valve disc 281a, fourth one-way valve disc 281b, valve hole 282, compensation channel 3, connecting pipe 31, channel 32, O-ring groove 4, O-ring 5, through hole 6, gasket 7, cooling fan 8, long screw 9. DETAILED DESCRIPTION

[0036] Example 1, see Figures 1 to 10 The present invention includes a dual-output shaft motor 1, wherein the two output ends of the dual-output shaft motor 1 are respectively connected to a single-head diaphragm pump 2; the single-head diaphragm pump 2 includes a head cover 21, a valve plate 22, a pump housing 23, a diaphragm 24 and a connecting rod assembly 25; the head cover 21 is provided with an inlet pipe 211 and an outlet pipe 212; the upper end surface of the valve plate 22 is tightly and sealingly connected to the head cover 21, and forms an independent inlet cavity 26, an outlet cavity 27 and a compensation cavity 28; the lower end surface of the valve plate 22 is provided with a chamber 221; After the lower end surface of the valve plate 22 is tightly and sealedly connected to the pump housing 23, the valve plate 22 and the pump housing 23 press and fix the edge of the diaphragm 24; specifically, after the head cover 21 and the valve plate 22 are tightly connected, a press-fitting groove for pressing the edge of the diaphragm 24 is formed; and annular protrusions are relatively provided on the upper and lower side walls of the press-fitting groove. When the head cover 21 and the valve plate 22 are tightly connected, the annular protrusions can squeeze and deform the edge of the diaphragm 24, prompting the diaphragm 24 to be tightly pressed in the press-fitting groove, and at the same time form a seal.

[0037] A sealed diaphragm cavity 29 is formed between the diaphragm 24 and the chamber 221; the inlet cavity 26, the outlet cavity 27 and the compensation cavity 28 are all connected to the sealed diaphragm cavity 29; The connecting rod assembly 25 is used to be fixedly connected to the diaphragm 24 and is in transmission connection with the output end of the corresponding side of the dual-output motor shaft 1; the connecting rod assembly 25 is used to drive the diaphragm 24 to reciprocate under the drive of the output end; A first one-way valve disc 261 is provided at the connection between the inlet cavity 26 and the sealed diaphragm cavity 29, which only allows the medium (usually gas) to enter the sealed diaphragm cavity 29; a second one-way valve disc 271 is provided at the connection between the outlet cavity 27 and the sealed diaphragm cavity 29, which only allows the medium to enter the outlet cavity. The diaphragm pump 2 further includes a compensation channel 3 connecting the compensation cavities 28 of the two single-head diaphragm pumps 2. A third one-way valve disc 281a is provided at the connection between the compensation cavity 28 of one of the single-head diaphragm pumps 2 and the sealed diaphragm cavity 29 on its corresponding side, allowing only the medium to enter the compensation cavity. A fourth one-way valve disc 281b is provided at the connection between the compensation cavity 28 of the other single-head diaphragm pump 2 and the sealed diaphragm cavity 29 on its corresponding side, allowing only the medium to enter the sealed diaphragm cavity 29. The compensation channel 3 includes a connecting pipe 31 and a channel 32 provided on the head cover 21 and communicating with the compensation cavity 28; both ends of the connecting pipe 31 are connected to the channels 32 on the two head covers 21; the connecting pipe 31 and the channels 32 on the two head covers 21 form the compensation channel 3, which can be seen in FIG. Figure 4 .

[0038] See also Figure 7The head cover 21 is also provided with an anti-stupid pin. The valve plate 22 is provided with a socket that cooperates with the anti-stupid pin. Through the cooperation between the anti-stupid pin and the socket, the head cover 21 and the valve plate 22 can be fast and accurately fastened.

[0039] The connecting rod assembly 25 includes an upper fixer 251, a fastening bolt 252, a lower fixer 253, a connecting rod 254, a bearing 255 and an eccentric wheel 256; the diaphragm 24 is located between the upper fixer 251 and the lower fixer 253; the upper fixer 251 is located on one side of the closed diaphragm cavity 29; the fastening bolt 252 passes through the upper fixer 251 and the lower fixer 253 of the diaphragm 24 from top to bottom, and is fixedly connected to the upper end of the connecting rod 254; the lower end of the connecting rod 254 is provided with a bearing sleeve 254-1; the eccentric wheel 256 is fixedly connected to the output end of the corresponding side of the dual-output shaft motor 1, and the outer part of the eccentric wheel 256 is provided with a bearing 255; the bearing 255 is installed in the bearing sleeve 254-1 of the connecting rod 254 on the corresponding side; the connecting rod 254 performs up and down reciprocating motion under the action of the driven eccentric wheel 256, and drives the diaphragm 24 to perform up and down reciprocating motion.

[0040] The lower fixer 253 includes a disc-shaped reference plate and a first connecting hole arranged in the center of the reference plate; the upper fixer 251 includes a disc-shaped pressing plate and a second connecting hole arranged in the center of the pressing plate; the lower end surface of the pressing plate and the upper end surface of the reference plate are pressed and fixed to the diaphragm 24 by fastening bolts 252, and specifically, the lower end surface of the pressing plate is also provided with an annular convex tooth; when the upper fixer 251 and the lower fixer 253 are fastened together by the fastening bolts, the annular convex tooth squeezes and deforms the diaphragm 24, thereby forming a seal while forming a compressed installation, and the seal mainly ensures the sealing of the fastening bolts 252 passing through the diaphragm 24.

[0041] The outer edge of the upper surface of the reference plate forms a bearing surface 253-1 that is inclined downward outward. The outer edge of the upper surface of the press plate forms a first inclined surface 251-1 that is inclined downward outward. The press plate is provided with a second inclined surface 251-2 in the thickness direction that is connected to the first inclined surface 251-1 and inclined inward. The diameter of the chamber side surface of the chamber 221 gradually decreases from its lower end opening to the chamber top surface; the chamber side surface includes a naturally connected annular arc surface 221-1, a chamfered arc surface 221-2, and an annular inclined surface 221-3 in sequence from its lower end opening to the chamber top surface; When the diaphragm 24 is at the upward limit position, the gap A between the outer edge of the bearing surface 253-1 and the annular curved surface 221-1 on the side of the groove is 2.88 mm to 3.07 mm; the gap B between the inner edge of the bearing surface 253-1 and the annular curved surface 221-1 on the side of the groove is 2.59 mm to 2.77 mm; the gap C between the lower edge of the second inclined surface 251-2 and the annular inclined surface 221-3 on the side of the groove is 1.13 mm to 1.24 mm; the gap D between the junction of the second inclined surface 251-2 and the first inclined surface 251-1 and the annular inclined surface 221-3 on the side of the groove is 0.86 mm to 1.06 mm; and the gap E between the inner edge of the first inclined surface 251-1 and the top surface of the chamber 221 is 0.96 mm to 1.24 mm. the gap F between the highest position of the upper fixture 251 and the top surface of the chamber 221 is: 0.53mm~0.73mm.

[0042] The two single-head diaphragm pumps 2 are symmetrically arranged; a first circular groove 221-4, a second circular groove 221-5 and a third circular groove 221-6 are provided on the upper end surface of the valve plate 22; a fourth circular groove 213, a fifth circular groove 214 and a sixth circular groove 215 corresponding to the first circular groove 221-4, the second circular groove 221-5 and the third circular groove 221-6 are respectively provided on the end surface of the head cover 21 facing the upper end surface of the valve plate 22; when the head cover 21 is fastened to the valve plate 22, the first circular groove 221-4 and the fourth circular groove 213 cooperate to form an inlet cavity 26, the second circular groove 221-5 and the fifth circular groove 214 cooperate to form an outlet cavity 27, and the third circular groove 221-6 and the sixth circular groove 215 cooperate to form a compensation cavity 28; When the head cover 21 is fastened to the valve plate 22, O-ring grooves 4 are formed between the head cover 21 and the valve plate 22 around the outside of the inlet cavity 26, the outlet cavity 27, and the compensation cavity 28. An O-ring 5 is installed in each O-ring groove 4. When the head cover 21 is fastened to the valve plate 22, each O-ring 5 is deformed under pressure and forms a seal with the corresponding inlet cavity 26, outlet cavity 27, or compensation cavity 28. The bottoms of the first circular groove 221-4, the second circular groove 221-5, and the third circular groove 221-6 are all connected to the sealed diaphragm cavity 29 through the through hole 6; the inlet pipe 211 is connected to the fourth circular groove 213 through the inlet hole; and the outlet pipe 212 is connected to the fifth circular groove 214 through the outlet hole. The first circular groove 221-4 and the second circular groove 221-5 are both provided with a plurality of through holes 6, and the number of through holes 6 on the first circular groove 221-4 is greater than the number of through holes 6 on the second circular groove 221-5. The number of through holes 6 provided on the third circular groove 221-6 of one single-head diaphragm pump 2 provided with the third one-way valve disc 281a is less than the number of through holes 6 provided on the third circular groove 221-6 of the other single-head diaphragm pump 2. In this embodiment, the first circular groove 221-4 is provided with five through holes 6; the second circular groove 221-5 is provided with four through holes 6; the third circular groove 221-6 of the single-head diaphragm pump 2 provided with the third one-way valve disc 281a has one through hole 6, and the third circular groove 221-6 of the other single-head diaphragm pump 2 has three through holes 6.

[0043] The five through holes 6 on the first circular groove 221-4 are distributed in a circular array along the central axis of the first circular groove 221-4 within an angle range of less than 360° (equivalent to being offset to one side); the three through holes 6 on the third circular groove 221-6 with three through holes 6 are distributed in a circular array along the central axis of the third circular groove 221-6 within an angle range of less than 360°.

[0044] The inlet holes include two inlet holes symmetrically arranged along the central axis of the fifth circular groove 214 ; the outlet holes include two outlet holes symmetrically arranged along the central axis of the sixth circular groove 215 .

[0045] The first circular groove 221 - 4 , the second circular groove 221 - 5 and the third circular groove 221 - 6 are all arranged in the first flat area 222 of the valve plate 22 ; the fourth circular groove 213 , the fifth circular groove 214 and the sixth circular groove 215 are all arranged in the second flat area 216 of the head cover 21 .

[0046] The four corners and the middle of the valve plate 22 form a valve plate connection area 223, and a first grid forming area 224 is formed between the valve plate connection area 223 and the first flat area 222; the four corners and the middle of the head cover 21 form a head cover connection area 217, and a second grid forming area 218 is formed between the head cover connection area 217 and the second flat area 216; when the head cover 21 is tightly connected to the valve plate 22, the first flat area 222 and the second flat area 216 correspond to each other.

[0047] The head cover connection area 217 of the head cover 21 and the valve plate connection area 223 of the valve plate 22 are fastened together by connecting bolts. Since the head cover 21 and the valve plate 22 are also fastened together in the middle, the vacuum degree is further ensured.

[0048] In this embodiment, the head cover connection area 217 in the middle is connected to the second flat area 216; the valve plate connection area 223 is connected to the first flat area 222. This design can further tighten the head cover 21 and the valve plate 22 near the inlet cavity 26 and the outlet cavity 27, further improving the vacuum level.

[0049] At least one shim 7 is provided between the lower retainer 253 and the upper end of the connecting rod 254, through which the fastening bolt 252 passes and for adjusting the distance between the lower retainer 253 and the upper end of the connecting rod 254. By selecting shims 7 of varying thicknesses or numbers to adjust the distance between the lower retainer 253 and the upper end of the connecting rod 254, the top clearance during the stroke can be adjusted.

[0050] The output ends on both sides of the dual-output shaft motor 1 are fixed with cooling fans 8; the cooling fans 8 are located in the pump housing 23 and rotate under the drive of the output end; the connecting rod assembly 25 is located between the cooling fan 8 on the corresponding side and the dual-output motor 1.

[0051] The pump housing 23 is provided with heat dissipation holes 231 .

[0052] The pump housing 23 is provided with a connecting flange 232; the pump housings 23 of the two single-head diaphragm pumps 2 are respectively mounted on both ends of the dual-output motor 1; the two pump housings 23 are fastened together by a locking nut after a long screw 9 passes through their respective connecting flanges 232.

[0053] The working process of the present invention is as follows: The output terminals at both ends of the dual-output shaft motor 1 drive the corresponding connecting rod assembly 25 to move up and down; the connecting rod assembly 25 drives the corresponding diaphragm 24 to reciprocate up and down. As the diaphragm 24 moves up and down, the medium enters the inlet chamber 26 from the inlet pipe 211, then enters the sealed diaphragm chamber 29 from the inlet chamber 26, then enters the sealed diaphragm chamber 29 from the sealed diaphragm chamber 29, enters the outlet chamber 27, and then enters the outlet pipe 212 from the outlet chamber 27, and is finally pumped out of the outlet pipe 212.

[0054] At the beginning of each pumping process, when the pressure difference between the single-head diaphragm pump 2 equipped with the third one-way valve plate 281a and the other single-head diaphragm pump 2 is very small, the two single-head diaphragm pumps 2 operate in parallel because the compensation channel 3 is closed by the third one-way valve plate 281a and the fourth one-way valve plate 281b at this time; when the pressure in the single-head diaphragm pump 2 equipped with the third one-way valve plate 281a is greater than the pressure in the other single-head diaphragm pump 2 and exceeds a certain pressure difference, the third one-way valve plate 281a and the fourth one-way valve plate 281b open, and the two single-head diaphragm pumps 2 work in series through the compensation channel 3.

[0055] Example 2, see Figure 11In the present invention, a third one-way valve plate 281a is provided at the connection between the compensation cavity 28 of a single-head diaphragm pump 2 and the closed diaphragm cavity 29 on its corresponding side, which only allows the medium to enter the compensation cavity 28; the other single-head diaphragm pump 2 omits the compensation cavity 28 and instead connects the compensation channel 3 with the closed diaphragm cavity 29 of the single-head diaphragm pump 2 through a reduced-diameter valve hole 282.

[0056] Other technical features are the same as those in Example 1.

[0057] The specific embodiments described above further illustrate the objectives, technical solutions and beneficial effects of the present invention in detail. It should be understood that the above are only specific embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. A series-parallel two-stage vacuum diaphragm pump, comprising a dual-output shaft motor, wherein each output end of the dual-output shaft motor is connected to a single-head diaphragm pump; characterized in that: The single-head diaphragm pump includes a head cover, a valve plate, a pump housing, a diaphragm and a connecting rod assembly; the head cover is provided with an inlet pipe and an outlet pipe; the upper end surface of the valve plate is tightly and sealedly connected to the head cover, and forms an independent inlet cavity, an outlet cavity and a compensation cavity; the lower end surface of the valve plate is provided with a chamber; After the lower end surface of the valve plate is tightly and sealedly connected to the pump housing, the valve plate and the pump housing press and fix the edge of the diaphragm; a closed diaphragm cavity is formed between the diaphragm and the chamber; the inlet cavity, outlet cavity and compensation cavity are all connected to the closed diaphragm cavity; The connecting rod assembly is used to be fixedly connected to the diaphragm and is transmission-connected to the output ends of the corresponding sides of the dual-output motor shaft; the connecting rod assembly is used to drive the diaphragm to reciprocate under the drive of the output end; A first one-way valve is provided at the connection between the inlet cavity and the sealed diaphragm cavity, which only allows the medium to enter the sealed diaphragm cavity; a second one-way valve is provided at the connection between the outlet cavity and the sealed diaphragm cavity, which only allows the medium to enter the outlet cavity; It also includes a compensation channel connecting the compensation cavities of two single-head diaphragm pumps; a third one-way valve is provided at the connection between the compensation cavity of one single-head diaphragm pump and the closed diaphragm cavity on its corresponding side, which only allows the medium to enter the compensation cavity.

2. A series-parallel two-stage vacuum diaphragm pump according to claim 1, characterized in that: The connecting rod assembly includes an upper fixer, a fastening bolt, a lower fixer, a connecting rod, a bearing and an eccentric wheel; the diaphragm is located between the upper fixer and the lower fixer; the upper fixer is located on one side of the closed diaphragm cavity; the fastening bolt passes through the upper fixer, the diaphragm and the lower fixer in sequence from top to bottom, and is fixedly connected to the upper end of the connecting rod; a bearing sleeve is provided at the lower end of the connecting rod; the eccentric wheel is fixedly connected to the output end of the corresponding side of the dual-output shaft motor, and a bearing is sleeved on the outside of the eccentric wheel; the bearing is installed in the bearing sleeve of the connecting rod on the corresponding side; the connecting rod performs up and down reciprocating motion under the action of the driven eccentric wheel, and drives the diaphragm to perform up and down reciprocating motion.

3. The series-parallel two-stage vacuum diaphragm pump according to claim 1, characterized in that: A third one-way valve disc is provided at the connection between the compensation cavity of one single-head diaphragm pump and the closed diaphragm cavity on its corresponding side, which only allows the medium to enter the compensation cavity; a fourth one-way valve disc is provided at the connection between the compensation cavity of the other single-head diaphragm pump and the closed diaphragm cavity on its corresponding side, which only allows the medium to enter the closed diaphragm cavity.

4. The series-parallel two-stage vacuum diaphragm pump according to claim 2, characterized in that: The lower holder includes a disc-shaped reference plate and a first connection hole provided at the center of the reference plate; the upper holder includes a disc-shaped pressing plate and a second connection hole provided at the center of the pressing plate; the lower end surface of the pressing plate and the upper end surface of the reference plate are press-fitted and fixed to the diaphragm by fastening bolts; The outer edge of the upper surface of the reference plate forms a bearing surface that is inclined downwardly outward; the outer edge of the upper surface of the press plate forms a first inclined surface that is inclined downwardly outward; the press plate is provided with a second inclined surface in the thickness direction that is connected to the first inclined surface and inclined inwardly; The diameter of the chamber side surface gradually decreases from the lower end opening to the chamber top surface; the chamber side surface includes a naturally connected annular arc surface, a chamfered arc surface, and an annular inclined surface in sequence from the lower end opening to the chamber top surface; When the diaphragm stroke is at the upward limit position, the gap between the outer edge of the bearing surface and the annular arc surface on the side of the chamber is: 2.88~3.07mm; the gap between the inner edge of the bearing surface and the annular arc surface on the side of the chamber is: 2.59mm~2.77mm; the gap between the lower edge of the second inclined surface and the annular inclined surface on the side of the chamber is: 1.13mm~1.24mm; the gap between the junction of the second inclined surface and the first inclined surface and the annular inclined surface on the side of the chamber is: 0.86mm~1.06mm; the gap between the inner edge of the first inclined surface and the top surface of the chamber is: 0.96mm~1.06mm; the gap between the highest position of the upper fixer and the top surface of the chamber is: 0.53mm~0.73mm.

5. The series-parallel two-stage vacuum diaphragm pump according to claim 1, characterized in that: Two single-head diaphragm pumps are symmetrically arranged; a first circular groove, a second circular groove and a third circular groove are provided on the upper end surface of the valve plate; a fourth circular groove, a fifth circular groove and a sixth circular groove are respectively provided on the end surface of the head cover facing the upper end surface of the valve plate, which correspond to the first circular groove, the second circular groove and the third circular groove; when the head cover is fastened to the valve plate, the first circular groove and the fourth circular groove cooperate to form an inlet cavity, the second circular groove and the fifth circular groove cooperate to form an outlet cavity, and the third circular groove and the sixth circular groove cooperate to form a compensation cavity; When the head cover is fastened to the valve plate, O-ring grooves are formed between the head cover and the valve plate around the outside of the inlet cavity, outlet cavity and compensation cavity. An O-ring is installed in each O-ring groove. When the head cover is fastened to the valve plate, each O-ring is deformed under pressure and forms a seal for the corresponding inlet cavity, outlet cavity or compensation cavity. The bottoms of the first circular groove, the second circular groove, and the third circular groove are all connected to the sealed diaphragm cavity through through holes; the inlet pipe is connected to the fourth circular groove through the inlet hole; and the outlet pipe is connected to the fifth circular groove through the outlet hole. Both the first circular groove and the second circular groove are provided with multiple through holes, and the number of through holes on the first circular groove is greater than the number of through holes on the second circular groove; the number of through holes on the third circular groove of one of the single-head diaphragm pumps provided with a third one-way valve plate is less than the number of through holes on the third circular groove of the other single-head diaphragm pump.

6. The series-parallel two-stage vacuum diaphragm pump according to claim 5, characterized in that: The first circular groove is provided with five through holes; the second circular groove is provided with four through holes; the third circular groove of the single-head diaphragm pump provided with the third one-way valve plate is provided with a through hole, and the third circular groove of the other single-head diaphragm pump is provided with three through holes.

7. A series-parallel two-stage vacuum diaphragm pump according to claim 5 or 6, characterized in that: The multiple through holes on the first circular groove are distributed in a circular array along the central axis of the first circular groove within an angular range of less than 360°; the multiple through holes on the third circular groove provided with multiple through holes are distributed in a circular array along the central axis of the third circular groove within an angular range of less than 360°.

8. The series-parallel two-stage vacuum diaphragm pump according to claim 5, characterized in that: The inlet hole includes two inlet holes symmetrically arranged along the central axis of the fifth circular groove; the outlet hole includes two outlet holes symmetrically arranged along the central axis of the sixth circular groove.

9. The series-parallel two-stage vacuum diaphragm pump according to claim 5, characterized in that: The first circular groove, the second circular groove and the third circular groove are all arranged in the first flat area of ​​the valve plate; the fourth circular groove, the fifth circular groove and the sixth circular groove are all arranged in the second flat area of ​​the head cover.

10. The series-parallel two-stage vacuum diaphragm pump according to claim 9, characterized in that: The four corners of the valve plate form a valve plate connection area, and a first grid forming area is formed between the valve plate connection area and the first flat area; the four corners of the head cover form a head cover connection area, and a second grid forming area is formed between the head cover connection area and the second flat area; when the head cover is tightly connected to the valve plate, the first flat area and the second flat area correspond to each other.

11. The series-parallel two-stage vacuum diaphragm pump according to claim 10, characterized in that: A valve plate connection area is further provided in the middle of the valve plate, and a head cover connection area is further provided in the middle of the head cover; the head cover connection area of ​​the head cover and the valve plate connection area of ​​the valve plate are fastened together by connecting bolts.

12. The series-parallel two-stage vacuum diaphragm pump according to claim 2, characterized in that: At least one gasket is provided between the lower fixer and the upper end of the connecting rod, through which a fastening bolt passes and which is used to adjust the distance between the lower fixer and the upper end of the connecting rod.

13. The series-parallel two-stage vacuum diaphragm pump according to claim 2, characterized in that: The output ends on both sides of the dual-output shaft motor are fixed with cooling fans; the cooling fans are located in the pump housing and rotate under the drive of the output end; the connecting rod assembly is located between the cooling fans on the corresponding side and the dual-output motor.

14. A series-parallel two-stage vacuum diaphragm pump according to claim 1, 2 or 13, characterized in that: The pump housing is provided with heat dissipation holes.

15. The series-parallel two-stage vacuum diaphragm pump according to claim 1, characterized in that: The pump housing is provided with a connecting flange; the pump housings of the two single-head diaphragm pumps are respectively mounted on both ends of the dual-output motor; the two pump housings are fastened together by locking nuts after a long screw passes through their respective connecting flanges.

16. The series-parallel two-stage vacuum diaphragm pump according to claim 1, characterized in that: A third one-way valve is provided at the connection between the compensation cavity of one single-head diaphragm pump and the closed diaphragm cavity on its corresponding side, which only allows the medium to enter the compensation cavity; the other single-head diaphragm pump does not have a compensation cavity, and its compensation channel is connected to the closed diaphragm cavity of the single-head diaphragm pump through a valve hole.

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