Series-parallel two-stage vacuum diaphragm pump

Abstract

This invention relates to a series-parallel two-stage vacuum diaphragm pump, comprising a dual-output shaft motor, with each of the two output ends of the motor connected to a single-head diaphragm pump. Each single-head diaphragm pump includes a head cover, a valve plate, a pump housing, a diaphragm, and a connecting rod assembly. The head cover has an inlet pipe and an outlet pipe. The upper end face of the valve plate is tightly sealed to the head cover, forming independent inlet, outlet, and compensation chambers. After the lower end face of the valve plate is tightly sealed to the pump housing, the valve plate and pump housing press-fit and fix the edge of the diaphragm, forming a sealed diaphragm cavity. The inlet, outlet, and compensation chambers are all connected to the sealed diaphragm cavity. The connecting rod assembly, driven by the output ends, drives the diaphragm to reciprocate. It also includes a compensation channel connecting the compensation chambers of the two single-head diaphragm pumps. This invention combines the advantages of series and parallel operation, using differential pressure to control the opening and closing of the vacuum valve to meet the requirements of high flow rate and high vacuum. Simultaneously, by optimizing the design of the sealed diaphragm cavity, the vacuum level is further improved.

Description

Technical Field

[0001] This invention relates to the field of vacuum pumps, and particularly to a series-parallel two-stage vacuum diaphragm pump. Background Technology

[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 belongs to the category of oil-free dry pumps. The working principle of a vacuum diaphragm pump is based on the reciprocating motion of the diaphragm. When the motor drives the diaphragm to move up and down, the volume of the pump chamber changes accordingly, thereby achieving gas intake and exhaust. Due to its high efficiency, oil-free operation, and corrosion resistance, vacuum diaphragm pumps are widely used in many fields.

[0003] Existing vacuum diaphragm pump designs include a configuration where two diaphragm pumps are synchronously driven by a dual-output-shaft motor. This design typically includes both series and parallel configurations.

[0004] For series connection, please refer to Figure 12 The air inlet and outlet of the head cover are connected in series by air pipes to form a series structure. The advantage of the series structure is that it is simple in structure, but the disadvantages are: (1) Under the same speed and stroke, the series structure can only obtain a high vacuum flow rate, which is only half that of the parallel structure, and cannot meet the flow rate requirements; (2) It is limited by the motor characteristics and pump body size design, and it is costly to increase the speed or modify the pump body.

[0005] For parallel connection, please refer to the following: Figure 13 It uses a gas pipe to connect the two separately operating gas outlet pipes in parallel, forming a parallel gas path. At the same speed and stroke, although the flow rate of the parallel type is twice that of the series type, the vacuum degree is only about 80%, which cannot meet the requirements of high vacuum.

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

[0007] The purpose of this invention is to provide a series-parallel two-stage vacuum diaphragm pump, which combines the advantages of series and parallel operation. It uses differential pressure to control the opening and closing of the vacuum valve to meet the requirements of high flow rate and high vacuum. Furthermore, by optimizing the design of the sealed diaphragm cavity, the vacuum level is further improved.

[0008] The technical solution to achieve the purpose of this invention is as follows: This invention includes a dual-output shaft motor, with each of the two output ends of the dual-output shaft motor 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 face of the valve plate is tightly sealed to the head cover, forming an independent inlet chamber, an outlet chamber, and a compensation chamber; the lower end face of the valve plate is provided with a chamber;

[0009] After the lower end face of the valve plate is tightly and sealed to the pump casing, the valve plate and the pump casing press and fix the edge of the diaphragm; a sealed diaphragm cavity is formed between the diaphragm and the chamber; the inlet cavity, outlet cavity and compensation cavity are all connected to the sealed diaphragm cavity;

[0010] The connecting rod assembly is used to fix and connect to the diaphragm, and is also connected to the output end of the corresponding side 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.

[0011] The inlet chamber is provided with a first one-way valve at the connection between the inlet chamber and the sealed diaphragm chamber, allowing only the medium to enter the sealed diaphragm chamber; the outlet chamber is provided with a second one-way valve at the connection between the outlet chamber and the sealed diaphragm chamber, allowing only the medium to enter the outlet chamber.

[0012] It also includes a compensation channel connecting the compensation chambers of two single-head diaphragm pumps; a third one-way valve is provided at the connection between the compensation chamber of one of the single-head diaphragm pumps and the corresponding sealed diaphragm chamber, allowing only the medium to enter the compensation chamber.

[0013] Furthermore, the aforementioned connecting rod assembly includes an upper retainer, a fastening bolt, a lower retainer, a connecting rod, a bearing, and an eccentric wheel; the diaphragm is located between the upper and lower retainers; the upper retainer is located on one side within the sealed diaphragm cavity; the fastening bolt passes through the upper retainer, diaphragm, and lower retainer sequentially 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 fitted on the outside of the eccentric wheel; the bearing is installed in the bearing sleeve of the corresponding side of the connecting rod; the connecting rod reciprocates up and down under the action of the driven eccentric wheel, and drives the diaphragm to reciprocate up and down.

[0014] Furthermore, one of the single-head diaphragm pumps has a third check valve at the connection between its compensation chamber and the corresponding sealed diaphragm chamber, which allows only the medium to enter the compensation chamber; the other single-head diaphragm pump has a fourth check valve at the connection between its compensation chamber and the corresponding sealed diaphragm chamber, which allows only the medium to enter the sealed diaphragm chamber.

[0015] Furthermore, the lower fixing device includes a disc-shaped reference plate and a first connecting hole located at the center of the reference plate; the upper fixing device includes a disc-shaped pressing plate and a second connecting hole located at the center of the pressing plate; the lower end face of the pressing plate and the upper end face of the reference plate are pressed and fixed to the diaphragm by fastening bolts.

[0016] The outer edge of the upper surface of the reference plate forms a bearing surface that slopes downward outward; the outer edge of the upper surface of the press plate forms a first inclined surface that slopes downward outward; the press plate has a second inclined surface in the thickness direction that connects with the first inclined surface and slopes inward.

[0017] The diameter of the side surface of the chamber gradually decreases from its lower opening to the top surface of the chamber; the side surface of the chamber from its lower opening to the top surface of the chamber successively includes a naturally connected annular arc surface, a chamfered arc surface, and an annular inclined surface;

[0018] When the diaphragm travels to its upper limit, the gap between the outer edge of the bearing surface and the annular arc surface of the chamber side is 2.88~3.07mm; the gap between the inner edge of the bearing surface and the annular arc surface of the chamber side is 2.59mm~2.77mm; the gap between the lower edge of the second inclined surface and the annular inclined surface of the chamber side is 1.13mm~1.24mm; the gap between the junction of the second and first inclined surfaces and the annular inclined surface of the chamber side 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; and the gap between the highest position of the upper fixator and the top surface of the chamber is 0.53mm~0.73mm.

[0019] Furthermore, the two single-head diaphragm pumps are symmetrically arranged; the upper end face of the valve plate is provided with a first circular groove, a second circular groove, and a third circular groove; the end face of the head cover facing the upper end face of the valve plate is provided with a fourth circular groove, a fifth circular groove, and a sixth circular groove, which correspond one-to-one with the first, second, and third circular grooves; when the head cover is fastened to the valve plate, the first and fourth circular grooves cooperate to form an inlet cavity, the second and fifth circular grooves cooperate to form an outlet cavity, and the third and sixth circular grooves cooperate to form a compensation cavity;

[0020] After the head cover and valve plate are fastened together, O-ring grooves are formed around the inlet cavity, outlet cavity and differential cavity respectively between the head cover and valve plate; O-rings are installed in each O-ring groove; each O-ring is deformed under pressure when the head cover and valve plate are fastened together and forms a seal on the corresponding inlet cavity, outlet cavity or differential cavity.

[0021] The bottoms of the first, second, and third circular grooves are all connected to the sealed diaphragm cavity through through holes; the inlet pipe is connected to the fourth circular groove through an inlet hole; and the outlet pipe is connected to the fifth circular groove through an outlet hole.

[0022] Both the first and second circular grooves 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.

[0023] 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 with a third one-way valve plate is provided with one through hole, and the third circular groove of another single-head diaphragm pump is provided with three through holes.

[0024] Furthermore, the multiple through holes on the first circular groove are arranged in a circumferential array along the central axis of the first circular groove within an angle range of less than 360°; the multiple through holes on the third circular groove are arranged in a circumferential array along the central axis of the third circular groove within an angle range of less than 360°.

[0025] Furthermore, the aforementioned 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.

[0026] Furthermore, the first, second, and third circular grooves are all located in the first flat area of ​​the valve plate; the fourth, fifth, and sixth circular grooves are all located in the second flat area of ​​the head cover.

[0027] Furthermore, the four corners of the valve plate form valve plate connection areas, and the valve plate connection areas and the first flat area form a first grid forming area; the four corners of the head cover form head cover connection areas, and the head cover connection areas and the second flat area form a second grid forming area; when the head cover and the valve plate are fastened together, the first flat area and the second flat area cooperate accordingly.

[0028] Furthermore, the valve plate is provided with a valve plate connecting area in the middle, and the head cover is provided with a head cover connecting area in the middle; the head cover connecting area of ​​the head cover and the valve plate connecting area of ​​the valve plate are fastened together by connecting bolts.

[0029] Furthermore, at least one shim is provided between the lower retainer and the upper end of the connecting rod, through which a fastening bolt can pass and for adjusting the distance between the lower retainer and the upper end of the connecting rod.

[0030] Furthermore, cooling fans are fixedly installed on both output ends of the aforementioned dual-output shaft motor; the cooling fans are located inside the pump housing and rotate under the drive of the output ends; the connecting rod assembly is located between the cooling fans on the corresponding sides and the dual-output motor.

[0031] Furthermore, the pump casing is provided with heat dissipation holes.

[0032] Furthermore, the pump casing is provided with a connecting flange; the pump casings of the two single-head diaphragm pumps are respectively fitted onto both ends of the dual-output motor; the two pump casings are connected by long screws passing through their respective connecting flanges and then fastened with lock nuts.

[0033] As a variation of the design, one of the single-head diaphragm pumps has a third one-way valve plate at the connection between the compensation chamber and the corresponding sealed diaphragm chamber, which allows the medium to enter the compensation chamber only; the other single-head diaphragm pump does not have a compensation chamber, and it is connected to the sealed diaphragm chamber of the single-head diaphragm pump through a valve hole.

[0034] The present invention has the following positive effects: (1) The present invention can achieve the advantages of high vacuum and high flow rate of series and parallel structures by only changing the air inlet and outlet of the head cover and valve plate, without having to spend a lot of manpower, material resources and financial resources to re-verify the life of the whole pump, which greatly reduces the modification cost. In addition, the opening and closing of the third one-way valve plate is controlled by differential pressure to meet the requirements of high flow rate and high vacuum.

[0035] (2) The present invention further improves the vacuum level by optimizing the design of the upper and lower fixing devices of the fixed diaphragm and the top gap of the sealed diaphragm cavity during the stroke.

[0036] (3) The present invention can achieve parallel operation when the pressure difference is very small by means of the third one-way valve plate and the fourth one-way valve plate; and when the pressure difference is too high, they can be opened at the same time to achieve series operation. At the same time, since the compensation chambers of the two single-head diaphragm pumps are respectively equipped with the third one-way valve and the fourth one-way valve, they are not easy to be blocked and can be used as superheated steam vacuum pumps.

[0037] (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 easily adjust the height of the connecting rod assembly to meet the height tolerance requirements and facilitate the adjustment of the vacuum degree.

[0038] (5) The number of through holes in this invention can further improve the pump output 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 when there is water or water vapor.

[0039] (6) The design of the first and second flattening zones in this invention helps to control leakage and thus ensure vacuum.

[0040] (7) In this invention, a fastening connection position is added between the head cover and the valve plate at the corresponding positions of the first flat area and the second flat area, which can reduce the deformation of the head cover and the valve plate during production and installation, thereby further ensuring the vacuum degree.

[0041] (8) The design of the first grid forming area of ​​the valve plate and the second grid forming area of ​​the head cover in this invention is to make the wall thickness of the parts more uniform, which is conducive to controlling the deformation degree of the head cover and valve plate forming, while increasing the surface area of ​​the head cover and valve plate and improving heat dissipation.

[0042] (9) The present invention can further actively dissipate heat from the inside of the pump casing by means of a cooling fan.

[0043] (10) The heat dissipation holes on the pump casing in this invention can further improve the heat dissipation effect. Attached Figure Description

[0044] To make the content of this invention easier to understand, the invention will be further described in detail below with reference to specific embodiments and accompanying drawings, wherein...

[0045] Figure 1 This is a schematic diagram of the structure of the present invention;

[0046] Figure 2 This is a schematic diagram of the series-parallel gas path in this invention;

[0047] Figure 3 This is a schematic cross-sectional view of the series-parallel structure in this invention;

[0048] Figure 4 This is a longitudinal sectional view of the present invention;

[0049] Figure 5 This is a cross-sectional view of the single-head diaphragm pump in this invention;

[0050] Figure 6 This is a schematic diagram of the head cover structure in this invention;

[0051] Figure 7 This is a schematic diagram of the end faces of the two headcaps facing the valve plate in this invention;

[0052] Figure 8 This is a schematic diagram of the valve plate structure in this invention;

[0053] Figure 9 This is a cross-sectional view of the valve plate in this invention;

[0054] Figure 10 This is a schematic diagram of the interior of the sealed diaphragm cavity of the present invention;

[0055] Figure 11 This is a schematic cross-sectional view of the series-parallel structure in Embodiment 2 of the present invention;

[0056] Figure 12 A schematic diagram of the gas path for an existing series-connected vacuum diaphragm pump;

[0057] Figure 13 This is a schematic diagram of the gas path for an existing parallel vacuum diaphragm pump.

[0058] In the diagram, the components are: dual-output shaft motor 1, single-head diaphragm pump 2, head cover 21, valve plate 22, pump housing 23, diaphragm 24, connecting rod assembly 25, inlet chamber 26, outlet chamber 27, compensation chamber 28, sealed diaphragm chamber 29, inlet pipe 211, outlet pipe 212, fourth circular groove 213, fifth circular groove 214, sixth circular groove 215, second flat area 216, head cover connecting area 217, second mesh forming area 218, chamber 221, first flat area 222, valve plate connecting area 223, first mesh forming area 224, heat dissipation hole 231, connecting flange 232, upper retainer 251, fastening bolt 252, lower retainer 253, and 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 Plate; 261, Second One-Way Valve Plate; 271, Third One-Way Valve Plate; 281a, Fourth One-Way Valve Plate; 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 Implementation

[0059] Example 1, see Figures 1 to 10 The present invention includes a dual-output shaft motor 1, the two output ends of which 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 face of the valve plate 22 is tightly sealed to the head cover 21, forming an independent inlet cavity 26, an outlet cavity 27, and a compensation cavity 28; the lower end face of the valve plate 22 is provided with a chamber 221;

[0060] After the lower end face of the valve plate 22 is tightly and sealed 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 is tightly connected to the valve plate 22, a pressing groove is formed to press the edge of the diaphragm 24. The upper and lower side walls of the pressing groove are provided with annular protrusions. When the head cover 21 is tightly connected to the valve plate 22, the annular protrusions can squeeze and deform the edge of the diaphragm 24, so that the diaphragm 24 is tightly pressed into the pressing groove, and at the same time, a seal is formed.

[0061] 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.

[0062] The connecting rod assembly 25 is used to be fixedly connected to the diaphragm 24 and to be driven by 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;

[0063] The inlet chamber 26 is provided with a first one-way valve 261 at the connection between the sealed diaphragm chamber 29 and the inlet chamber 26, which allows only the medium (generally gas) to enter the sealed diaphragm chamber 29; the outlet chamber 27 is provided with a second one-way valve 271 at the connection between the outlet chamber 27 and the sealed diaphragm chamber 29, which allows only the medium to enter the outlet chamber.

[0064] It also includes a compensation channel 3 that connects the compensation chambers 28 of the two single-head diaphragm pumps 2; a third one-way valve plate 281a is provided at the connection between the compensation chamber 28 of one single-head diaphragm pump 2 and the corresponding sealed diaphragm chamber 29, which allows only the medium to enter the compensation chamber; a fourth one-way valve plate 281b is provided at the connection between the compensation chamber 28 of the other single-head diaphragm pump 2 and the corresponding sealed diaphragm chamber 29, which allows only the medium to enter the sealed diaphragm chamber 29.

[0065] The compensation channel 3 includes a connecting pipe 31 and a channel 32 disposed on the head cover 21 and communicating with the compensation cavity 28; both ends of the connecting pipe 31 are respectively 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, as shown in [reference]. Figure 4 .

[0066] See Figure 7 The head cover 21 is also provided with a foolproof pin. The valve plate 22 is provided with a socket that mates with the foolproof pin. By engaging the foolproof pin with the socket, the head cover 21 and the valve plate 22 can be quickly and accurately fastened together.

[0067] The connecting rod assembly 25 includes an upper retainer 251, a fastening bolt 252, a lower retainer 253, a connecting rod 254, a bearing 255, and an eccentric wheel 256. The diaphragm 24 is located between the upper retainer 251 and the lower retainer 253. The upper retainer 251 is located on one side within the sealed diaphragm cavity 29. The fastening bolt 252 passes through the upper retainer 251 and the lower retainer 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 dual output shaft motor 1 on the corresponding side, and the bearing 255 is fitted on the outside of the eccentric wheel 256. The bearing 255 is installed in the bearing sleeve 254-1 of the connecting rod 254 on the corresponding side. The connecting rod 254 reciprocates up and down under the action of the driven eccentric wheel 256, and drives the diaphragm 24 to reciprocate up and down.

[0068] The lower fixture 253 includes a disc-shaped reference plate and a first connecting hole located at the center of the reference plate; the upper fixture 251 includes a disc-shaped pressing plate and a second connecting hole located at the center of the pressing plate; the lower end face of the pressing plate and the upper end face of the reference plate are pressed and fixed to the diaphragm 24 by fastening bolts 252, specifically, the lower end face of the pressing plate is also provided with annular protrusions; when the upper fixture 251 and the lower fixture 253 are fastened together by fastening bolts, the annular protrusions compress and deform the diaphragm 24, thereby forming a seal while forming a pressurized installation. This seal is mainly to ensure the seal at the point where the fastening bolts 252 pass through the diaphragm 24.

[0069] The outer edge of the upper surface of the reference plate forms a bearing surface 253-1 that slopes outward and downward; the outer edge of the upper surface of the press plate forms a first inclined surface 251-1 that slopes outward and downward; the press plate has a second inclined surface 251-2 in the thickness direction that connects with the first inclined surface 251-1 and slopes inward.

[0070] The diameter of the side surface of the chamber 221 gradually decreases from its lower opening to the top surface of the chamber; the side surface of the chamber from its lower opening to the top surface of the chamber includes, in sequence, a naturally connected annular arc surface 221-1, a chamfered arc surface 221-2, and an annular inclined surface 221-3;

[0071] When the diaphragm 24 is at its upper limit position, the gap A between the outer edge of the bearing surface 253-1 and the annular arc surface 221-1 on the side of the groove is 2.88mm~3.07mm; the gap B between the inner edge of the bearing surface 253-1 and the annular arc surface 221-1 on the side of the groove is 2.59mm~2.77mm; 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 1.13mm~1.24mm; 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 0.86mm~1.06mm; and the gap E between the inner edge of the first inclined surface 251-1 and the top surface of the chamber 221 is 0.96mm~ 1.06mm; the gap F between the highest position of the upper fixator 251 and the top surface of the chamber 221 is 0.53mm~0.73mm.

[0072] Two single-head diaphragm pumps 2 are symmetrically arranged; the upper end face of the valve plate 22 is provided with a first circular groove 221-4, a second circular groove 221-5, and a third circular groove 221-6; the end face of the head cover 21 facing the upper end face of the valve plate 22 is provided with a fourth circular groove 213, a fifth circular groove 214, and a sixth circular groove 215, which correspond one-to-one with the first circular groove 221-4, the second circular groove 221-5, and the third circular groove 221-6; 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;

[0073] After the head cover 21 is fastened to the valve plate 22, O-ring grooves 4 are formed around the outside of the inlet cavity 26, outlet cavity 27 and compensation cavity 28 between the head cover 21 and the valve plate 22; O-rings 5 ​​are installed in each O-ring groove 4; each O-ring 5 is deformed under pressure when the head cover 21 is fastened to the valve plate 22 and forms a seal on the corresponding inlet cavity 26, outlet cavity 27 or compensation cavity 28.

[0074] 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.

[0075] Both the first circular groove 221-4 and the second circular groove 221-5 are provided with multiple 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 on the third circular groove 221-6 of one of the single-head diaphragm pumps 2 equipped with a third one-way valve plate 281a is less than the number of through holes 6 on the third circular groove 221-6 of the other single-head diaphragm pump 2. Specifically, 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 equipped with a third one-way valve plate 281a is provided with one through hole 6, and the third circular groove 221-6 of the other single-head diaphragm pump 2 is provided with three through holes 6.

[0076] The five through holes 6 on the first circular groove 221-4 are arranged in a circumferential 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 are arranged in a circumferential array along the central axis of the third circular groove 221-6 within an angle range of less than 360°.

[0077] The inlet hole includes two inlet holes symmetrically arranged along the central axis of the fifth circular groove 214; the outlet hole includes two outlet holes symmetrically arranged along the central axis of the sixth circular groove 215.

[0078] The first circular groove 221-4, the second circular groove 221-5 and the third circular groove 221-6 are all located 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 located in the second flat area 216 of the head cover 21.

[0079] The four corners and the middle of the valve plate 22 form valve plate connecting areas 223, and the valve plate connecting areas 223 and the first flat area 222 form a first mesh forming area 224; the four corners and the middle of the head cover 21 form head cover connecting areas 217, and the head cover connecting areas 217 and the second flat area 216 form a second mesh forming area 218; when the head cover 21 and the valve plate 22 are fastened together, the first flat area 222 and the second flat area 216 are correspondingly engaged.

[0080] The head cover 21 connecting area 217 of the head cover 21 and the valve plate connecting 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 guaranteed.

[0081] In this embodiment, the head cover connecting area 217 in the middle is connected to the second flat area 216; the valve plate connecting area 223 is connected to the first flat area 222. This design allows the head cover 21 and the valve plate 22 to be further pressed together near the inlet cavity 26 and outlet cavity 27, further improving the vacuum level.

[0082] At least one shim 7 is provided between the lower retainer 253 and the upper end of the connecting rod 254, through which a fastening bolt 252 can pass, and for adjusting the distance between the upper ends of the lower retainer 253 and the connecting rod 254. By selecting shims 7 of different thicknesses or different numbers of shims 7, the distance between the upper ends of the lower retainer 253 and the connecting rod 254 can be adjusted, which is actually adjusting the top clearance during the stroke.

[0083] Cooling fans 8 are fixedly installed on both sides of the output ends of the dual-output shaft motor 1; the cooling fans 8 are located inside the pump housing 23 and rotate under the drive of the output ends; the connecting rod assembly 25 is located between the cooling fans 8 and the dual-output motor 1 on the corresponding side.

[0084] The pump casing 23 is provided with heat dissipation holes 231.

[0085] 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 fitted onto both ends of the dual-output motor 1; the two pump housings 23 are connected by a long screw 9 passing through their respective connecting flanges 232 and then fastened by a lock nut.

[0086] The working process of this invention is as follows:

[0087] The output 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 sequentially 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 outlet chamber 27 from the sealed diaphragm chamber 29, then enters the outlet pipe 212 from the outlet chamber 27, and finally is pumped out from the outlet pipe 212.

[0088] At the start of each pumping process, when the pressure difference between the single-head diaphragm pump 2 equipped with the third one-way valve 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 281a and the fourth one-way valve 281b at this time; when the pressure in the single-head diaphragm pump 2 equipped with the third one-way valve 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 281a and the fourth one-way valve 281b open, and the two single-head diaphragm pumps 2 operate in series through the compensation channel 3.

[0089] Example 2, see Figure 11 In this invention, a third one-way valve plate 281a is provided at the connection between the compensation chamber 28 of a single-head diaphragm pump 2 and the corresponding sealed diaphragm chamber 29, which allows the medium to enter the compensation chamber 28 only; another single-head diaphragm pump 2 omits the compensation chamber 28 and instead connects the compensation channel 3 to the sealed diaphragm chamber 29 of the single-head diaphragm pump 2 through a reduced-diameter valve hole 282.

[0090] Other technical features are the same as in Example 1.

[0091] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely 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 within the protection scope of the present invention.

Claims

1. A series-parallel two-stage vacuum diaphragm pump, comprising 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; 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 face of the valve plate is tightly sealed to the head cover, forming an independent inlet chamber, an outlet chamber, and a compensation chamber; the lower end face of the valve plate is provided with a chamber. After the lower end face of the valve plate is tightly and sealed to the pump casing, the valve plate and the pump casing press and fix the edge of the diaphragm; a sealed diaphragm cavity is formed between the diaphragm and the chamber; the inlet cavity, outlet cavity and compensation cavity are all connected to the sealed diaphragm cavity; The connecting rod assembly is used to fix and connect to the diaphragm, and is also connected to the output end of the dual-output shaft motor on the corresponding side. The connecting rod assembly is used to drive the diaphragm to reciprocate under the drive of the output end. The inlet chamber is provided with a first one-way valve at the connection between the inlet chamber and the sealed diaphragm chamber, allowing only the medium to enter the sealed diaphragm chamber; the outlet chamber is provided with a second one-way valve at the connection between the outlet chamber and the sealed diaphragm chamber, allowing only the medium to enter the outlet chamber. It also includes a compensation channel connecting the compensation chambers of two single-head diaphragm pumps; a third one-way valve is provided at the connection between the compensation chamber of one of the single-head diaphragm pumps and the corresponding closed diaphragm chamber, which allows the medium to enter the compensation chamber only. The connecting rod assembly includes an upper retainer, a fastening bolt, a lower retainer, a connecting rod, a bearing, and an eccentric wheel; the diaphragm is located between the upper and lower retainers; the upper retainer is located on one side within the sealed diaphragm cavity; the fastening bolt passes through the upper retainer, diaphragm, and lower retainer sequentially 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 fitted 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 reciprocates up and down under the action of the driven eccentric wheel, and drives the diaphragm to reciprocate up and down.

2. The series-parallel two-stage vacuum diaphragm pump according to claim 1, characterized in that: One of the single-head diaphragm pumps has a third check valve at the connection between its compensation chamber and the corresponding sealed diaphragm chamber, which allows only the medium to enter the compensation chamber; the other single-head diaphragm pump has a fourth check valve at the connection between its compensation chamber and the corresponding sealed diaphragm chamber, which allows only the medium to enter the sealed diaphragm chamber.

3. The series-parallel two-stage vacuum diaphragm pump according to claim 1, characterized in that: The lower fixing device includes a disc-shaped reference plate and a first connecting hole located at the center of the reference plate; the upper fixing device includes a disc-shaped pressing plate and a second connecting hole located at the center of the pressing plate; the lower end face of the pressing plate and the upper end face of the reference plate are pressed and fixed to the diaphragm by fastening bolts. The outer edge of the upper surface of the reference plate forms a bearing surface that slopes downward outward; the outer edge of the upper surface of the press plate forms a first inclined surface that slopes downward outward; the press plate has a second inclined surface in the thickness direction that connects with the first inclined surface and slopes inward. The diameter of the side surface of the chamber gradually decreases from its lower opening to the top surface of the chamber; the side surface of the chamber from its lower opening to the top surface of the chamber successively includes a naturally connected annular arc surface, a chamfered arc surface, and an annular inclined surface; When the diaphragm travels to its upper limit, the gap between the outer edge of the bearing surface and the annular arc surface of the chamber side is 2.88~3.07mm; the gap between the inner edge of the bearing surface and the annular arc surface of the chamber side is 2.59mm~2.77mm; the gap between the lower edge of the second inclined surface and the annular inclined surface of the chamber side is 1.13mm~1.24mm; the gap between the junction of the second and first inclined surfaces and the annular inclined surface of the chamber side 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; and the gap between the highest position of the upper fixator and the top surface of the chamber is 0.53mm~0.73mm.

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

5. A series-parallel two-stage vacuum diaphragm pump according to claim 4, characterized in that: The first circular groove has five through holes; the second circular groove has four through holes; the third circular groove of the single-head diaphragm pump with a third one-way valve plate has one through hole, and the third circular groove of another single-head diaphragm pump has three through holes.

6. A series-parallel two-stage vacuum diaphragm pump according to claim 4 or 5, characterized in that: The multiple through holes on the first circular groove are arranged in a circumferential array along the central axis of the first circular groove within an angle range of less than 360°; the multiple through holes on the third circular groove are arranged in a circumferential array along the central axis of the third circular groove within an angle range of less than 360°.

7. A series-parallel two-stage vacuum diaphragm pump according to claim 4, 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.

8. A series-parallel two-stage vacuum diaphragm pump according to claim 4, characterized in that: The first, second, and third circular grooves are all located in the first flat area of ​​the valve plate; the fourth, fifth, and sixth circular grooves are all located in the second flat area of ​​the head cover.

9. A series-parallel two-stage vacuum diaphragm pump according to claim 8, characterized in that: The four corners of the valve plate form a valve plate connection area, and the valve plate connection area and the first flat area form a first grid forming area; the four corners of the head cover form a head cover connection area, and the head cover connection area and the second flat area form a second grid forming area; when the head cover and the valve plate are fastened together, the first flat area and the second flat area cooperate accordingly.

10. A series-parallel two-stage vacuum diaphragm pump according to claim 9, characterized in that: The valve plate is further provided with a valve plate connecting area in the middle, and the head cover is further provided with a head cover connecting area in the middle; the head cover connecting area of ​​the head cover and the valve plate connecting area of ​​the valve plate are fastened together by connecting bolts.

11. A series-parallel two-stage vacuum diaphragm pump according to claim 1, characterized in that: At least one shim is provided between the lower retainer and the upper end of the connecting rod, through which a fastening bolt can pass and for adjusting the distance between the lower retainer and the upper end of the connecting rod.

12. A series-parallel two-stage vacuum diaphragm pump according to claim 1, characterized in that: Cooling fans are fixedly installed at the output ends on both sides of the dual-output shaft motor; the cooling fans are located inside the pump housing and rotate under the drive of the output ends; the connecting rod assembly is located between the cooling fans and the dual-output motor on the corresponding sides.

13. A series-parallel two-stage vacuum diaphragm pump according to claim 1 or 12, characterized in that: The pump casing is provided with heat dissipation holes.

14. A series-parallel two-stage vacuum diaphragm pump according to claim 1, characterized in that: The pump casing is provided with a connecting flange; the pump casings of the two single-head diaphragm pumps are respectively fitted onto both ends of the dual-output motor; the two pump casings are connected by long screws passing through their respective connecting flanges and then fastened with lock nuts.

15. A series-parallel two-stage vacuum diaphragm pump according to claim 1, characterized in that: One of the single-head diaphragm pumps has a third one-way valve at the connection between its compensation chamber and the corresponding sealed diaphragm chamber, which allows the medium to enter the compensation chamber only; the other single-head diaphragm pump does not have a compensation chamber, and it is connected to the sealed diaphragm chamber of the single-head diaphragm pump through a valve hole.

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