EP2483559A2

EP2483559A2 - Multi-stage diaphragm suction pump

Info

Publication number: EP2483559A2
Application number: EP10745570A
Authority: EP
Inventors: Erich Becker; Erwin Hauser
Original assignee: KNF Neuberger GmbH
Current assignee: KNF Neuberger GmbH
Priority date: 2009-09-29
Filing date: 2010-08-18
Publication date: 2012-08-08
Anticipated expiration: 2030-08-18
Also published as: CN102667151A; WO2011038807A2; JP2013506084A; ES2425545T3; US9004877B2; KR20120083880A; JP5511966B2; WO2011038807A8; US20120189468A1; EP2483559B1; KR101793750B1; DE102009043644A1; DE102009043644B4; CN102667151B; WO2011038807A3

Abstract

The invention relates to a multi-stage diaphragm suction pump, comprising at least two pump chambers, each having a fluid inlet having at least one inlet valve, and a fluid outlet having at least one outlet valve, and a suction line, which connects the fluid inlets of the pump chambers. Consecutive pump chambers are connected to each other by means of at least one connection line such that, when a differential pressure in the suction line is reached/exceeded, the diaphragm pump changes from parallel operation of the pump chambers thereof to an operating mode of said pump chambers that is at least also serial. At least one check valve, which opens to the downstream pump stage, is interposed in each of the inflow and outflow regions of the at least one connection line. In order to optimize the pump characteristic of such a diaphragm suction pump, according to the invention at least in one pump chamber, either in order to improve the intake pressure the suction-side opening of the at least one connection line, or in order to improve the suction capacity the pressure-side opening of the at least one connection line, is disposed in the region of the pump chamber, or in the vicinity of the region of the pump chamber, on which the diaphragm associated with said pump chamber rolls off first during a pump cycle. In addition, or instead, according to a further embodiment at least one connection line, in particular between successive pump chambers, has a descending line progression and, for this purpose, compared to the outflow-side line segment, the inflow-side line segment of said at least one connection line is arranged at a higher level.

Description

Multi-stage membrane suction pump

The invention relates to a multi-stage diaphragm suction pump having at least two pump chambers, each having a fluid inlet having at least one inlet valve and a fluid outlet having at least one outlet valve and a suction line connecting the fluid inlets of the pumping chambers, wherein each subsequent pumping space is in each case via at least one Connecting line are connected to each other such that the diaphragm pump on reaching / exceeding a differential pressure in the suction line from a parallel operation of their pumping chambers in an at least also serially operating operation of these pumping rooms passes, and wherein in the inflow and outflow of the at least one connecting line in each case at least a, the subsequent pumping stage opening check valve is interposed.

When evacuating, for example, an autoclave, on the one hand a large flow rate is desired, on the other hand, a good final vacuum. The large flow rate is achieved by parallel connection of the heads, the good final vacuum through multi-stage operation, ie by series connection. In many applications, especially in the laboratory, a low final pressure is required, which can only be achieved with a multi-stage arrangement. From WO 2004/088138 already known a micro-vacuum pump, which has two, each limited by an oscillating pumping diaphragm pump chambers. Each of these pump chambers has a fluid inlet having an inlet valve and a fluid outlet having an outlet valve, one of the fluid inlets the suction chambers connecting the pumping chambers and one, the fluid outlets connecting pressure line is provided. The pump chambers are connected to one another via a connecting line in such a way that the previously known micro-vacuum pump, upon reaching and exceeding a defined differential pressure in the suction line, transitions from a parallel operation of its pump chambers into a series-operating operation of these pump chambers. Both in the inflow region and in the outflow region of the connecting line, a check valve which opens for the subsequent pumping stage is interposed in each case. In order to reduce the effort associated with the production of the previously known membrane suction pump, the non-return valves interposed in the connecting line have a size comparable to the inlet and outlet valves of the two pumping chambers. Accordingly, the line section of the connecting line provided between one of the check valves, on the one hand, and the adjacent pump chamber, on the other hand, is dimensioned comparably large. Nevertheless, in order to be able to initially guide the fluid flow in the start phase of a pumping operation via the inlet and outlet valves connected in parallel, a throttle is interposed in the connecting line, which loses its throttling effect only when a corresponding pressure difference and a reduced pumping capacity are reached.

At the beginning of the suction process, the previously known micro-vacuum pump adopts a parallel configuration of its pumping chambers, because the throttle provided in the connecting line causes the system initially to be able to work more easily in parallel because of the still missing obstructions in the air circulation. As soon as this parallel operating configuration comes within the range of the final vacuum and the pressure difference in the suction line reaches a maximum, For example, the fluid can flow much more easily through the restrictor located in the connection line, so that it is also configured in a serial operation of their pumping chambers in order to achieve the highest possible ultimate vacuum.

However, it is disadvantageous that the check valves of the previously known membrane pump have a size comparable to the inlet and outlet valves, and that the line sections of the connecting line provided between the check valves have a correspondingly large clear line cross section, so that a correspondingly large line cross section occurs in these line sections large harmful space results, which affects the achievable final vacuum of the prior art membrane suction pump and the switching point between parallel and serial operation negatively affected.

In order to achieve as high a final vacuum as possible in the shortest possible time and in order to approach the optimum switching point between parallel and serial operation, a multi-stage diaphragm pump has also been created, in which the inlet and outlet areas of the connecting line (FIG. en) provided check valves are smaller compared to the inlet and outlet valves of the pump chambers and that these check valves each one adjacent to the adjacent pumping space open line section of the connecting line with a smaller compared to the inlet and outlet valves clear line cross-section is assigned (see 10 2007 057 945 A1). It is clear from a comparison of FIGS. 1 and 2 and the 90 ° sectional illustration in FIG. 4 of DE 10 2007 057 945 A1 that the inlet and outlet openings of the connecting lines in the crankshaft plane are also arranged in this previously known diaphragm pump. This known diaphragm pump has in the at least one, their pumping rooms with each other connecting connecting line on both inflow and outflow check valves, which are dimensioned much smaller compared to the inlet and outlet valves of these pump chambers. Since the movable valve body of these check valves thus also have lower masses and can react faster, an approximation to the optimal switching point between parallel and serial operation is substantially favored. Since the connecting line becomes effective only in the region of the optimal switching point, and since the connecting lines only have to handle comparatively low flow rates in this pumping phase, the clear cross section of the connecting lines can be made comparatively small in comparison with the suction line and the pressure line. This also makes it possible to carry out the check valves provided in the at least one connecting line with a very small flow cross section and correspondingly small diameter compared to the suction and pressure valves. Thus, the check valves due to the low mass of their movable valve or locking body when closing the suction and pressure valves react quickly and thereby prevent the previously known from DE 10 2007 057 945 A1 diaphragm pump in a transition region of the pressure differences does not or only insufficiently , Since the check valves in each case a leading to the adjacent pumping space line section is assigned, which has a substantially smaller clear line cross-section compared to the inlet and outlet valves, the remaining between a check valve on the one hand and the adjacent pump chamber on the other hand harmful space can be kept so low that the generation of a very low final vacuum is possible. The previously known from DE 10 2007 057 945 A1 diaphragm pump therefore allows the production of a possible with relatively simple technical means low final vacuum in the shortest possible time.

In the prior art membrane pumps known from WO 2004/0881 38 and DE 1 0 2007 057 945 A1, the pressure and suction-side openings of the connection lines are provided approximately centrally between the pressure and suction valves of the pump chambers in a line arranged axially parallel to the pivot axis , Since in each pump chamber the working diaphragm which rolls off at the pump chamber wall only reaches the openings of the connecting lines approximately at its dead center, leakage currents can escape via these openings of the connecting lines which adversely affect the performance of these diaphragm pumps.

It is therefore an object to provide a multi-stage diaphragm pump of the type mentioned above, which is characterized by its pumping characteristics optimized in terms of their suction or ^' their pumping speed.

An inventive solution to this problem is in the multi-stage diaphragm pump of the type mentioned in particular that at least in a pump chamber either to improve the suction pressure, the suction-side opening of the at least one connecting line or to improve the pumping speed, the pressure-side opening of the at least one connecting line in the Area of the pump chamber is arranged or approximated to this area, to which the pump chamber associated with this first during a pumping cycle rolls.

The pump chambers of the membrane pump according to the invention are connected to one another via connecting lines. In this case, the subsequent pumping in the conveying direction pumping chambers also have a suction-side opening, which is associated with a connecting line. To improve the suction pressure in at least one of subsequent suction chambers provided suction-side opening of at least one connecting line in the region of the pump chamber arranged or approximated to this area, in which the pump chamber associated with this first drum during a pumping cycle. In this embodiment, therefore, to improve the suction pressure, the arrangement of the suction-side opening of the at least one connecting line out of the center line oriented at the top dead center to Pleuelschwenkebene centered out preferably about -45 ° in the direction of the area of the pump chamber, in which this pump space associated The diaphragm rolls off during a pumping cycle first. Namely, the switching from parallel to serial pump operation of the multi-stage diaphragm pump comes about when the suction pressure in the following stage is lower than the discharge pressure in the previous stage. In order for this effect to occur, the crank angle of the crank mechanism assigned to the connecting rod must preferably be arranged offset from head to head by 180 °. The closer the small suction-side opening of a connection line is in the connecting-rod plane, on the side of the sealing space on which the connecting rod is deflected in the upward direction by the tilting movement of the connecting rod in the direction of rotation and results in the lower by the proximity to the connecting rod swing plane the suction pressure. The lowest intake pressure in the next stage results when the small intake-side opening of at least one connecting line lies exactly in the connecting-rod swing plane. Each position between the zero point and the connecting rod plane results in its own intake pressure. In this way, one can influence the transition of the suction curve of the pump connected in parallel to the suction curve of the pump connected in series. In this case, influencing is already possible if the arrangement of the suction-side opening in the mentioned direction is changed only in one of the pumping stages. The process starts at the first pumping stage and continues gradually on the other heads and pumping stages. By possibly also different pivoting angles in the arrangement of the suction-side opening of the connecting lines connecting the pumping stages to one another in the direction of the connecting rod swinging plane, the transitional region in the course of the curve can be influenced by suction pressure and pumping speed.

If, instead, the pumping speed is to be improved, it is also possible, at least in one pumping stage, to arrange the pressure-side opening of the at least one connecting line in the area of the pumping space or to approach that area at which the diaphragm assigned to this pumping space first rolls during a pumping cycle. To improve the pumping speed, it is thus possible to preferably rotate the arrangement of the pressure-side opening of the at least one connecting line out of the center line oriented at top dead center to the connecting rod pivot plane by approximately + 45 ° in the direction of the region of the pump chamber in which the pump chamber assigned membrane during a pumping cycle first rolls. Since, in this embodiment, the pressure-side opening of the connecting line provided in this pump chamber is closed at an early stage by the working diaphragm which rolls on the pump chamber wall, any leakage currents which otherwise lead via the connecting lines can be significantly reduced and the pumping speed can be improved.

In this case, a preferred embodiment according to the invention provides that each pump chamber of the diaphragm pump is associated with a pivotable in a connecting rod connecting rod and that at least in a pump chamber, the suction side or the pressure side opening of at least one connecting line is provided in the Pleuelschwingebene. An optimization of the pump characteristics is further promoted if the suction-side or the pressure-side opening of the at least one connecting line is arranged in the edge region of the pumping space adjacent to the clamping zone of the membrane.

A preferred embodiment according to the invention provides that at least in a pump chamber, the suction-side or the pressure-side opening of the at least one connecting line and the suction valve are arranged approximately on a line extending transversely to Pleuelschwingebene line.

Such multi-stage diaphragm suction pumps are often used as vacuum pumps for pumping off moist vapors. Under unfavorable pressure and temperature conditions, condensation may occur in the last and previous stages. This is usually prevented by using a gas ballast valve. Depending on the evaporation properties of the condensate, however, such a gas ballast valve leads to a significant deterioration of the final vacuum.

One method of achieving the maximum final vacuum despite condensate formation is the blowing out of the condensate which has occurred at atmospheric pressure (see DE 198 51 680 C2 and DE 100 21 454 A1). A disadvantage of this method, however, lies in the interruption of the evacuation process during the blow-out.

In parallel operation of the above-mentioned multi-stage diaphragm suction pumps, the maximum discharge pressure is regularly higher than the evaporation pressure of the condensate. The condensate therefore has no influence on the evacuation process. In series operation of such Membra suction pumps falls below the End pressure of the pump, however, often the evaporation point of the condensate, so that due to the re-expansion of the condensate, the final pressure can not be achieved. Therefore, the condensate must be continuously blown out.

It is expedient if at least one connecting line has a falling line course, in particular between subsequent pumping chambers, and if, for this purpose, the inflow-side line section is arranged higher in comparison with the downstream line section of this at least one connecting line. With this falling arrangement of the at least one, in particular between subsequent pump chambers provided connecting line blowing out the condensate possibly occurring in the subsequent pump chambers is facilitated and the pump characteristics of the membrane suction pump according to the invention in terms of their pumping speed even favors. The condensate occurs regularly in the vicinity of the atmospheric pressure and thus usually in the last three stages of the series-connected pump chambers of the multi-stage diaphragm suction pump. A designed according to this proposal invention membrane pump is characterized by a continuous evacuation process, although any condensate is constantly blown out by the working gas itself. In the case of pumps with two or more heads, the Boxer form offers a space-saving design. A preferred embodiment according to the invention therefore provides that the pump stages of the multi-stage diaphragm pump are arranged in pairs in a boxer form.

In a lying in a lying position Boxer form both sides parallel to the axis heads can be easily interconnected horizontally. If, however, according to the invention proposal mentioned above, an optimization of the suction curve by changing the switching pressures by means of a staggered arrangement of the openings provided in the pumping space of the connecting lines, located in the mounted on both sides of the pump housing heads suction side openings of the connecting lines in the direction of Pleuelschwingebene and on the side of the head, in which the connecting rod is deflected in the upward direction by the tilting movement in the direction of rotation, be arranged. Characterized comes in the second pumping stage, the suction-side opening to lie over the axis, while the pressure-side opening in the third pumping stage can be placed under the axis, so that when lying position of such a boxer pump, a falling connection line is created.

By contrast, if the boxer pump described above is operated in a standing position, the connecting line between the second and the third pumping stage is arranged horizontally, while the connecting line between the third and the fourth pumping stage is arranged falling.

A preferred embodiment according to the invention therefore provides that the suction-side opening of the connecting line provided in the second pumping stage is arranged above the crank axle and / or the pressure-side opening of the connecting line provided in the third pumping stage is below the crank axle. In order to be able to blow out the condensate continuously, the cross-section of the connecting lines between the comparatively small-dimensioned check valves should be designed so that the gas velocity occurring therein is limited to Blow out the condensate is sufficient. In case of falling or horizontal arrangement of the connecting lines, this may lead to the lowest effective gas velocity. A preferred development according to the invention therefore provides that the connecting lines have a line diameter which is equal to or less than half the clear line cross section of the pressure or suction lines leading to the pressure or suction valves. A preferred embodiment according to the invention provides that the membrane suction pump has four pumping chambers and / or is designed in four stages.

Further developments according to the invention will become apparent from the claims and the drawings. The invention will be described in more detail below with reference to preferred embodiments.

1a shows a multi-stage diaphragm suction pump in a schematic plan view, wherein the pump stages of this suction pump are connected to one another via connecting lines which have suction and pressure-side openings leading to the pump chambers,

Fig.1b membrane suction pump from Fig.1a in a schematic tables representation of their pumping rooms, wherein in the pump chambers, the arrangement of the pressure and suction valves and the pressure and suction ports of the

Connection lines are shown,

1 c shows the membrane suction pump of FIGS. 1 a and 1 b in a schematic side view with a view of the drive motor,

1 a to 1 c comparable membrane suction pump in a schematic plan view,

2a shows the multi-stage diaphragm suction pump from FIG. 2a in a schematic representation of their pumping chambers, wherein the pressure-side openings of the connecting lines in the pump chambers are staggered compared to the arrangement shown in FIG. 1b in such a way that promotes high pumping speed becomes,

2 c shows the diaphragm suction pump from FIGS. 2 a and 2 b in a schematic side view with a view of the drive motor,

3a shows a configured according to the prior art multi-stage diaphragm suction pump in a schematic plan view,

3a shows the diaphragm suction pump of Figure 3a in a schematic representation of their pumping rooms, wherein in the pump chambers, the arrangement of the pressure and suction valves and the pressure and suction side openings of the connecting lines are shown and wherein the suction and pressure side openings of between the connecting stages provided on the pump stages are arranged practically on a line lying between the suction and the pressure valve,

3 c shows a schematic side view of the drive motor, the curve of suction pressure and pumping speed in the diaphragm pumps shown in Fig.1a to 1c, 2a to 2c and 3a to 3c, a multi-stage diaphragm suction pump in a schematic plan view, a diaphragm suction pump in a schematic representation of their pumping chambers with a with FIG. 3b comparable arrangement of the suction and pressure valves and the suction and pressure side openings of the connecting lines, a diaphragm suction pump in a schematic representation of their pumping chambers, the arrangement of the suction and the pressure valves and the suction and pressure side openings of the connecting lines of FIG 1b corresponds to a membrane suction pump in a schematic representation of their pump chambers, the arrangement of the suction and pressure valves and the suction and pressure side openings of the connecting lines of the arrangement shown in Fig.2b corresponds, a multi-stage diaphragm suction pump in one Side view overlooking the drive motor, a e for blowing out the condensate possibly occurring in the subsequent pumping rooms particularly advantageous arrangement of provided between the pumping stages connecting lines in a standing Boxerform trained Membra suction pump in a schematic plan view (Figure 6a) and in a schematic representation of their pumping chambers (Figure 6b), the arrangement of the pressure and suction valves and the suction and pressure side openings of the connecting lines of the in Figures 3b and 5b corresponds to an arrangement for blowing out the condensate possibly occurring in the following pumping chambers particularly advantageous arrangement of provided between the pumping stages connecting lines of a standing boxer form diaphragm suction pump in a schematic plan view and in a schematic representation of their pumping rooms, the arrangement of the suction - And pressure valves and the suction and pressure side openings of the connecting lines of the arrangement shown in Figures 1b and 5c substantially corresponds to, for blowing out the condensate possibly occurring in the subsequent pumping space particularly advantageous arrangement of between Fig. 5A) and in a schematic representation of their pumping chambers (Fig.5b), wherein the arrangement of the suction and pressure valves and the suction and pressure side openings of the pumping stages provided connecting lines of a formed in standing boxer form diaphragm suction pump Connecting lines corresponds to the arrangement shown in Figures 2b and 5d,

Fig.9 a for blowing out in the following Pump chambers possibly occurring condensate particularly advantageous arrangement of provided between the pumping stages connecting lines of a lying in a lying Boxer form diaphragm suction pump in a schematic side view (Figure 9a) and in a rotated by 90 ° schematic side view (Figure 9b),

10 shows a diaphragm suction pump comparable to FIGS. 9a and 9b in a schematic side view (FIG. 10a) and in a side view rotated by 90 ° (FIG. 10b), wherein the pump stages of this diaphragm suction pump have differently arranged connections - lines are connected to each other, and

11 shows a schematic comparison of the clear cross section of the connection lines provided between the pumping stages, on the one hand, and the inlet or outlet ducts leading to the suction valve or to the pressure valve, on the other hand.

FIGS. 1 to 3 and 5 to 10 show various embodiments of a multi-stage membrane suction pump 10, 100. The pump embodiments 10, 100 shown here each have four pump chambers 1, 2, 3 and 4, which are arranged in pairs in a boxer form. Each pump chamber 1, 2, 3, 4, 4 of these pump designs has a respective fluid inlet 6, which has an inlet valve, and a fluid outlet 7, which has an outlet valve. In this case, the fluid inlets 6 of the pump chambers 1, 2, 3, 4 are connected via a common suction line.

In addition, the stepwise successive pumping chambers 2, 3, 4 are each via a connecting line 8, 9, 11 connected to one another in such a way that the pump designs 10, 100 shown here, upon reaching or exceeding a differential pressure in the suction line, pass from a parallel operation of their pumping chambers 1, 2, 3, 4 into at least serial operation of these pumping chambers 1, 2, 3, 4 , In this case, at least one check valve opening to the subsequent pump stage is interposed in the inflow and outflow regions of the connecting lines 8, 9, 11, respectively. The check valves and provided in each pump chamber pressure and suction valves are controlled by the pressure differences of the medium to be delivered.

As indicated in FIG. 11, the check valves provided in the inflow and outflow regions of the connecting lines 8, 9, 11 are smaller in comparison with the inlet and outlet valves of the pump chambers 1, 2, 3, 4, wherein these check valves are each one assigned to the adjacent pumping space open line section of the connecting line with a smaller compared to the inlet and outlet valves clear line cross-section. The diaphragm pumps shown here have in their, the pump chambers 1,2,3,4 interconnecting connecting lines 8,9,11 both inflow and outflow check valves on, compared to the inlet and outlet valves of these pump chambers 1,2,3 , 4 are much smaller dimensions. Since the movable valve body of these check valves thus also have lower masses and can react faster, an approximation to the optimal switching point between parallel and serial operation is substantially favored. Since the connecting lines 8,9,11 become effective only in the region of the optimum switching point, and since the connecting lines 8,9,11 have to cope with only comparatively low flow rates in this pumping phase the clear cross-section of the connecting lines 8,9,11 compared to the suction and the pressure line are made relatively small. This also makes it possible to carry out the non-return valves provided in the at least one connecting line 8, 9, 11 with a very small flow cross-section and correspondingly small diameter compared with the suction and pressure valves. Thus, the check valves due to the low mass of their movable valve or locking body when closing the suction and pressure valves react quickly and thereby prevent the pumps shown here in a transition region of the pressure differences do not or only insufficiently. Since the check valves each associated with the adjacent pumping space line section is assigned, which has a much smaller clear line cross-section compared to the inlet and outlet valves, the remaining between a check valve on the one hand and the adjacent pump room remaining harmful space can be kept so low that the generation of a very low final vacuum is possible. The pump designs shown here therefore allow with comparatively simple technical means to generate the lowest possible final vacuum in the shortest possible time.

In FIGS. 3a to 3c and in FIG. 5b pump embodiments are shown, which essentially correspond to the hitherto known state of the art with regard to the arrangement of the openings in the pump space leading to the connecting lines. As is apparent from Figures 3b and 5b, the pressure and the suction side openings of the connecting lines are provided approximately centrally between the pressure and the suction valves of the pump chambers in an axially parallel to Pleueldrehachse arranged line in the prior art. Since in each pump chamber 1,2,3,4 the rolling off at the pump room wall Working diaphragm reaches the openings 12,13 of the connecting lines 8,9,11 until about the dead center, leakage currents can escape through these openings 12,13 of the connecting lines, which adversely affect the performance of these Pumpenaus- leadership.

As is clear from the curve of the suction pressure and the pumping speed marked "0 °" in FIG. 4, the pump designs shown in FIGS. 3 a to 3 c and 5 b have a comparatively low suction pressure and at the same time a comparatively low suction capacity.

In Fig. 3c is indicated that the pressure and suction side openings of the at least one connecting line are arranged on a transverse to the connecting rod pivot plane center line L. Comparing FIG. 1 c with FIG. 3 c, it becomes clear that the arrangement of the suction-side opening of the at least one connecting line to improve the suction pressure out of the center line L oriented at top dead center transversely to the connecting rod pivot plane, for example, by about -45 ° in the direction can be rotated to the region of the pumping space in which the membrane associated with this pumping space first rolls during a pumping cycle. This area is marked in Figure 3c with "B" and "C". By contrast, it is clear from a comparison of FIGS. 2c and 3c that the arrangement of the pressure-side opening of the at least one connecting line out of the center line L oriented at top dead center transversely to the connecting rod pivot plane preferably out by approximately + 45 ° in the direction of the region of Pumping space can be rotated, in which the associated pump chamber first rolls during a pumping cycle. In this case, the desired benefits can already be achieved if at least in the pump room the second in the conveying direction Pumping step to improve the suction pressure, the suction-side opening of the at least one connecting line is rotated or if the pressure-side opening is rotated at least in the pump chamber of the first pumping stage in the conveying direction to improve the pumping speed.

In contrast, the pump embodiments 10 illustrated in FIGS. 1, 2, 5c, 5d, 7, 8, 9 and 10 are characterized by pump characteristics optimized with regard to their suction pressure or their pumping speed.

Thus, in order to improve the suction pressure in the pump embodiments shown in FIGS. 1, 5, 7, 9 and 10, the suction-side opening 12 of the at least one connecting line 8, 9, 11 is arranged in the region of the pump chamber or approximates this region at which the latter Pumping assigned diaphragm pumping during a pumping cycle first. The suction-side opening 12 is thus offset from the pump longitudinal center plane, preferably by approximately 45 ° in the direction of the region of the pump chamber 2, 3, 4, and thus arranged in the hemisphere of the pumping space 2, 3, 4 into which the pump chamber faces The diaphragm is rolled over first during a pumping cycle.

Namely, the switching from the parallel to the serial pumping operation of the multi-stage diaphragm pumps shown here comes about when the suction pressure in the following stage is lower than the discharge pressure in the previous stage. In order for this effect to occur, the crank angle of the crank mechanism assigned to the connecting rod must preferably be arranged offset from head to head by 180 °. The closer the small suction-side opening 12 of a connecting line 8, 9 or 11 now lies in the connecting-rod swing plane, specifically on the side of the sealing space on which the connecting rod moves upwards through the Tilting movement of the connecting rod is deflected in the direction of rotation and by the proximity to the Pleuelschwingebene, the lower the suction pressure results. The lowest suction pressure in the next stage results when the small suction-side opening 12 of at least one connecting line 8, 9, 11 lies exactly in the connecting-rod swing plane. Each position between the zero point and the connecting rod plane results in its own intake pressure. In this way, one can influence the transition of the suction curve of the pump connected in parallel to the suction curve of the pump connected in series. In this case, an influence is already possible if only in one of the pump stages 2, 3, 4 the arrangement of the suction-side opening 12 in the mentioned direction is changed. The process begins at the first pumping stage 1 and continues, gradually over the other heads and pumping stages 2,3,4. By optionally also different pivoting angles in the arrangement of the suction-side opening 12 of the connecting sections 8, 9, 11 connecting the pumping stages 2, 3, 11 in the direction of the connecting-rod swinging plane, the transitional region in the course of the curve can be influenced by suction pressure and pumping speed.

In the pump embodiments shown in FIGS. 2, 5d and 8, the pumping speed should instead be improved. For this purpose, in at least one pump stage 1, 2, 3, 4, the pressure-side opening 10 of the at least one connecting line 8, 9, 11 is arranged in the area of the pump space 1, 2, 3, 4 or approximates this area, at which the pump space 1 thereof , 2,3,4 associated membrane during a pumping cycle first rolls. The pressure-side opening 13 is therefore offset from the pump longitudinal center plane preferably approximately at 45 ° in the direction of the region of the pumping space and thus arranged in the hemisphere of the pumping space, in which the diaphragm associated with this pumping space first rolls during a pumping cycle. FIG. 4 also shows the curve profile of suction pressure and pumping speed in the case of the pump designs shown in FIGS. 1,5c, 7, 9 and 10 on the one hand and in the pump designs illustrated in FIGS. 2, 5d and 8 on the other hand. While the curve progression indicated by "-45 ° / + 45 °" of the pump designs shown in FIGS. 1, 5, 7, 9 and 10 is characterized by an improved, namely additionally reduced, suction pressure, the curve "+ 45 ° / -. 45 ° "marked curve of the pump designs shown in Figures 2, 5d and 8 on an improved pumping speed.

As is clear from a comparison of Figures 1, 2, 3, 5c, 5d, 7, 8, 9 and 10, the pressure and the suction-side openings 12,13 of the at least one connecting line 8, 9,11 and in the Fluid inlet 6 provided suction valve arranged approximately on a line extending transversely to Pleuelschwingebene line.

The diaphragm suction pumps 10, 100 shown here can often also be used as vacuum pumps for pumping off moist vapors. However, under unfavorable pressure and temperature conditions, condensation may occur in the last and preceding stages 2, 3, 4. In parallel operation of the membrane suction pumps 10, 100, the maximum discharge pressure is regularly higher than the evaporation pressure of the condensate. The condensate therefore has no influence on the evacuation process. In series operation of such membrane suction pumps, however, the final pressure of the pump often falls below the evaporation point of the condensate, so that the final pressure can not be achieved due to the back expansion of the condensate.

In the pump embodiments shown in FIGS. 6 to 10, at least one connecting line 8, 9, 10 is in particular configured between subsequent pump chambers 2,3,4 with a falling line, for which the inflow-side line section 8,9,11 is higher compared to the downstream line section of the connecting lines. With this falling arrangement of the at least one, in particular between subsequent pump chambers 2,3,4 provided connecting line 8,9,11 blowing out the condensate possibly occurring in the subsequent pump chambers is facilitated and the pump characteristics of the diaphragm suction pumps shown here in terms of their pumping speed additionally favored. In this case, the condensate occurs regularly in the vicinity of the atmospheric pressure and thus usually in the last three stages of the series-connected pump chambers of the multi-stage diaphragm suction pumps. The membrane suction pumps shown here are characterized by a continuous evacuation process, although any condensate is constantly blown out by the working gas itself. As is clear from a comparison of Figures 9 and 10, located in the mounted on both sides of the pump housing heads suction openings 12 of the connecting lines 8, 9, 11 in the direction of Pleuelschwingebene and on the side of the head, in which the connecting rod at Upward stroke is deflected by the tilting movement in the direction of rotation, be arranged if one seeks to optimize the suction curve in terms of suction pressure by changing the switching pressures by means of a staggered arrangement of provided in the pump chamber 1,2,3,4 openings of the connecting lines 8, 9, 11 , Characterized comes in the second pumping stage 2, the suction-side opening 12 to lie over the axis, while the pressure-side opening in the third pumping stage 3 can be placed under the axis, so that when lying position of such a boxer pump, a falling connection line is created. In contrast, when the boxer pump described above is operated in a standing position as shown in FIGS. 6 to 8, the connecting line 8 is arranged horizontally between the second and third pumping stages 2, 3, while the connecting line 9 is arranged between the third and the fourth Pumping stage 3, 4 is arranged falling. An embodiment is preferred in which the suction-side opening 1 2 of the connecting line provided in the second pumping stage 2 is arranged above the crank axle and / or the pressure-side opening of the connecting line provided in the third pumping stage 3 below the crank axle (FIGS. 7b, 8b) ,

FIG. 11 schematically illustrates that the cross section d of the connecting lines 8, 9, 11 between the relatively small non-return valves should be designed so that the gas velocity occurring therein is sufficient to blow out the condensate. The connecting lines of the pump embodiments shown here therefore have a line diameter d, which is equal to or less than half of the clear line cross-section D of the leading to the pressure or suction valves pressure or suction lines. Thus, the lowest effective gas velocity is achieved with falling or horizontal arrangement of the connecting lines 8, 9, 1 1.

claims

Claims

claims

Multi-stage diaphragm suction pump (10) having at least two pump chambers (1, 2, 3, 4), each having a fluid inlet (6) having at least one inlet valve and a fluid outlet (7) having at least one outlet valve, and having one Fluid inlets (6) of the pump chambers (1,2,3,4) connecting suction line, wherein each subsequent pumping chambers (1,2,3,4) in each case via at least one connecting line (8,9,11) are interconnected such that the Membrane pump (10) on reaching / exceeding a differential pressure in the suction line of a parallel operating operation of their pumping chambers (1,2,3,4) merges into an at least also serially operating operation of these pumping rooms, and wherein in the inflow and outflow of the at least a connecting line (8,9,11) is interposed in each case at least one check valve opening to the subsequent pumping stage, characterized in that at least in a pumping space (1,2,3,4) either for improvement the suction-side opening (12) of the at least one connecting line (8, 9, 11) or for improving the pumping speed the pressure-side opening (13) of the at least one connecting line (8, 9, 11) in the area (B, C) the pump chamber (1,2,3,4) is arranged or approximates this region (B, C), at which the diaphragm associated with this pumping chamber first circulates during a pumping cycle.

Membrane suction pump according to claim 1, characterized in that each pump chamber (1, 2, 3, 4) of the diaphragm pump (10) is associated with a pivotable connecting rod in a connecting rod and that at least in one pump chamber (1, 2, 3, 4) the suction side or the pressure side opening (12,13) is provided at least one connecting line (8,9,11) in the Pleuelschwingebene.

Membrane suction pump according to claim 1 or 2, characterized in that the suction-side or the pressure-side opening (12,13) of the at least one connecting line (8,9,11) in the adjacent to the clamping zone of the membrane edge region of the pump chamber (1,2 , 3,4) is arranged.

Membrane suction pump according to one of claims 1 to 3, characterized in that at least in a pump chamber (1,2,3,4), the suction-side or the pressure-side opening (12,13) of the at least one connecting line (8,9,11) and the suction valve are arranged approximately on a line extending transversely to the Pleuelschwingebene line.

Membrane suction pump according to one of claims 1 to 4, characterized in that arranged at least in the pump chamber (2) in the conveying direction second pumping stage to improve the suction pressure, the suction side opening (12) of the at least one connecting line in the region of the pump chamber (2) or approximates this range, at which the membrane associated with this pumping room first rolls during a pumping cycle.

Membrane suction pump according to one of claims 1 to 4, characterized in that arranged at least in the pump chamber (1) in the conveying direction of the first pumping stage to improve the pumping speed, the pressure-side opening (13) of the at least one connecting line in the region of the pump chamber (1) or this Is approached, at which the membrane associated with this pumping space during a pumping cycle first.

Membrane suction pump according to one of claims 1 to 6, characterized in that at least one connecting line (8,9,11) in particular between subsequent pump chambers (1,2,3,4) has a falling line profile and that to the inflow-side line section in comparison to the outflow line section of this at least one connecting line (8,9,11) is arranged higher.

Membrane suction pump according to one of claims 1 to 7, characterized in that the pumping stages (1,2,3,4) of the multi-stage diaphragm pump (10,100) are arranged in pairs in a boxer form.

Membrane suction pump according to one of claims 1 to 8, characterized in that the suction-side opening (12) provided in the second pump stage (2) connecting line (9) above the crank axis and / or the pressure-side opening (13) in the third Pump stage (3) provided connecting line is arranged below the crank axle.

Membrane suction pump according to one of claims 1 to 9, characterized in that the connecting lines (8,9,11) have a line diameter which is equal to or less than half of the clear line cross-section of leading to the pressure or suction valves pressure or suction lines ,

Membrane suction pump according to one of claims 1 to 10, characterized in that the membrane suction pump (10,100) has four pump rooms (1,2,3,4).

12. membrane suction pump according to one of claims 1 to 11, characterized in that in the first and in the last pump chamber (1,4) of the successive pump chambers (1,2,3,4) at least one suction or pressure side opening of a connecting line and in the interposed pump chambers (2,3) at least one suction and at least one pressure-side opening of the connecting lines are provided.