EP2483559B1 - Multi-stage diaphragm suction pump - Google Patents

Description

The invention relates to a multi-stage membrane suction pump having at least two pump chambers, each having a driven by a connecting rod of a crank drive, rolling on a pump chamber wall membrane, and each have a, at least one inlet valve having fluid inlet and a, at least one outlet valve having fluid outlet, and with a suction line connecting the fluid inlets of the pumping chambers, wherein subsequent pumping spaces are connected to each other via at least one connecting line in such a way that the diaphragm pump reaches a differential pressure in the suction line from a parallel operation of its pumping spaces into at least also a serial operating mode transitions these pumping spaces, and wherein in the inflow and outflow of the at least one connecting line in each case at least one, 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 the WO 2004/088138 One already knows a micro-vacuum pump, the two, each by an oscillating pumping membrane has limited pump rooms. 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 chamber connecting the pumping chambers and a, 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 operating operation of its pumping chambers into a series-operating operation of these pumping 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 to be able to initially work more easily in parallel due to the still lacking 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.

The disadvantage, however, that the check valves of the prior art diaphragm pump have a size comparable to the inlet and outlet valves, and that provided between the check valves line sections of the connecting line have a correspondingly large clear line cross-section, so that in these line sections a correspondingly harmful Room results, which has an effect on the achievable final vacuum of the prior art membrane suction pump and negatively affected the switching point between parallel and serial operation.

In order to achieve as high a final vacuum as possible in the shortest possible time and to approach the optimum switching point between parallel and serial operation, a multi-stage diaphragm pump has already been created in which the in-flow and outflow regions of the connecting line (s) provided check valves compared to the inlet and outlet valves of the pump chambers are made smaller and that these check valves each associated with an 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. DE 10 2007 057 945 A1 ). From a comparison of Fig. 1 and 2 and the 90 ° section in FIG Fig. 4 of the DE 10 2007 057 945 A1 It is clear that even with this known membrane pump, the inlet and outlet openings of the connecting lines are arranged in the crank axis plane. This prior art membrane 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 is effective only in the region of the optimal switching point, and since the connecting lines in this pumping phase have to handle only comparatively low flow rates, the clear cross section of the connecting lines can be made relatively small compared to the suction 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 off DE 10 2007 057 945 A1 previously known diaphragm pump in a transition region of the pressure differences does not or only insufficiently promotes. 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. From DE 10 2007 057 945 A1 Previous diaphragm pump therefore allows the production of a possible with relatively simple technical means low final vacuum in the shortest possible time.

From the DE 10 2006 043 159 B3 Already known is a two-stage superheated steam pump, which has push-pull membranes as pumping organs. The two pump chambers have inlets and outlets equipped with check valves, which are each connected in parallel via lines. The pump chambers are connected via a control line which has a check valve arrangement. In order to produce a high ultimate vacuum as quickly as possible, is in the DE 10 2006 043 159 B3 provided that the valve members of the connecting line associated check valve assembly have a much lower mass than the valve members of the inlets and outlets of the pump chambers associated check valves.

Even with the out DE 10 2006 043 159 B3 Prior art diaphragm pump, the pressure and the suction side openings of the connecting line are provided approximately centrally between the pressure and suction valves of the pump chambers in an axis parallel to the Pleueldrehachse arranged line. Since in each pump chamber the working diaphragm which rolls off at the pump chamber wall only reaches the openings of the connecting line approximately at its dead center, leakage currents can escape via these openings of the connecting line which adversely affect the performance of these diaphragm pumps.

Something else does not arise from the FIGS. 2a and 2b in the opposite DE 10 2006 043 159 B3 , In the FIGS. 2a and 2b of the DE 10 2006 043 159 B3 in fact, only the fluid inlets and outlets connected to the pump chambers are shown cut longitudinally in the region of their non-return valves 1.5 and 1.6, while those outside the Cutting plane disposed suction and pressure side openings of the connecting connecting the pumping chambers connecting line not shown and are not visible. Rather, these openings are in the partially cross-sectional top view in FIG FIG. 3 visible in the area of their control valves 1.7 and 2.7 respectively. There, the suction and pressure side openings of the pumping spaces interconnecting connecting line are provided approximately centrally between the pressure and the suction valves of the pump chambers in an axis-parallel to the Pleueldrehachse arranged line.

At the WO 2004/088138 and from DE 10 2007 057 945 A1 Prior art membrane pumps, 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 axis parallel to the Pleueldrehachse arranged line. 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 or optimized in terms of their suction pressure or pumping characteristics.

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 at least one connecting line or to improve the pumping speed, the pressure-side opening of at least one Connecting line from the pump longitudinal center plane out offset in the hemisphere of the pump chamber is arranged, to which the pump chamber associated with this first changes during a pumping cycle.

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 connecting line in the Pleuelschwingebene is now, on the side of the seal chamber 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 the proximity to the Pleuelschwingebene, the lower results 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, you 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. Through possibly also different pivoting angles in the arrangement of the suction-side opening of the connecting lines connecting the pumping stages with each other in the direction of the connecting rod swing 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 enhanced 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 purging of the condensate which has occurred with atmospheric pressure (cf. 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 diaphragm 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 pumping chambers provided connecting line blowing out the condensate possibly occurring in the subsequent pump chambers is facilitated and further favors the pumping characteristics of the membrane suction pump according to the invention in terms of their pumping speed. 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.

Fig.1a

eine mehrstufige Membran-Saugpumpe in einer schematischen Draufsicht, wobei die Pumpstufen dieser Saugpumpe über Verbindungsleitungen miteinander verbunden sind, die zu den Pumpräumen führende saug- und druckseitige Öffnungen haben,

Fig.1b

die Membran-Saugpumpe aus Fig.1a in einer schematischen Darstellung ihrer Pumpräume, wobei in den Pumpräumen die Anordnung der Druck- und Saugventile sowie der druck- und saugseitigen Öffnungen der Verbindungsleitungen dargestellt sind,

Fig.1c

die Membran-Saugpumpe aus Fig.1a und 1b in einer schematischen Seitenansicht mit Blick auf den Antriebsmotor,

Fig.2a

eine mit Fig.1a bis 1c vergleichbare Membran-Saugpumpe in einer schematischen Draufsicht,

Fig.2b

die mehrstufige Membran-Saugpumpe aus Fig.2a in einer schematischen Darstellung ihrer Pumpräume, wobei die druckseitigen Öffnungen der Verbindungsleitungen in den Pumpräumen im Vergleich zu der in Fig.1b gezeigten Anordnung derart versetzt angeordnet sind, dass ein hohes Saugvermögen begünstigt wird,

Fig.2c

die Membran-Saugpumpe aus Fig.2a und 2b in einer schematischen Seitenansicht mit Blick auf den Antriebsmotor,

Fig.3a

eine gemäß dem Stand der Technik ausgestaltete mehrstufige Membran-Saugpumpe in einer schematischen Draufsicht,

Fig.3b

die Membran-Saugpumpe aus Fig.3a in einer schematischen Darstellung ihrer Pumpräume, wobei in den Pumpräumen die Anordnung der Druck- und Saugventile sowie der druck- und saugseitigen Öffnungen der Verbindungsleitungen dargestellt sind und wobei die saug- und druckseitigen Öffnungen der zwischen den Pumpstufen vorgesehenen verbindungsleitungen praktisch auf einer zwischen dem Saug- und dem Druckventil liegenden Linie angeordnet sind,

Fig.3c

die Membran-Saugpumpe aus Fig.3a und 3b in einer schematischen Seitenansicht mit Blick auf den Antriebsmotor,

Fig.4

den Kurvenverlauf von Ansaugdruck und Saugvermögen bei den in Fig.1a bis 1c, 2a bis 2c und 3a bis 3c dargestellten Membranpumpen,

Fig.5a

eine mehrstufige Membran-Saugpumpe in einer schematischen Draufsicht,

Fig.5b

eine Membran-Saugpumpe in einer schematischen Darstellung ihrer Pumpräume mit einer mit Fig.3b vergleichbaren Anordnung der Saug- und Druckventile sowie der saug- und druckseitigen Öffnungen der Verbindungsleitungen,

Fig.5c

eine Membran-Saugpumpe in einer schematischen Darstellung ihrer Pumpräume, wobei die Anordnung der Saug- und der Druckventile sowie der saug- und druckseitigen Öffnungen der Verbindungsleitungen der in Fig.1b gezeigten Anordnung entspricht,

Fig.5d

eine Membran-Saugpumpe in einer schematischen Darstellung ihrer Pumpräume, wobei die Anordnung der Saug- und Druckventile sowie der saug- und druckseitigen Öffnungen der Verbindungsleitungen der in Fig.2b gezeigten Anordnung entspricht,

Fig.5e

eine mehrstufige Membran-Saugpumpe in einer Seitenansicht mit Blick auf den Antriebsmotor,

Fig.6

eine zum Ausblasen des in den nachfolgenden Pumpräumen eventuell auftretenden Kondensats besonders vorteilhafte Anordnung der zwischen den Pumpstufen vorgesehenen Verbindungsleitungen einer in stehender Boxerform ausgebildeten Membran-Saugpumpe in einer schematischen Draufsicht (Fig.6a) sowie in einer schematischen Darstellung ihrer Pumpräume (Fig.6b), wobei die Anordnung der Druck- und Saugventile sowie der saug- und druckseitigen Öffnungen der Verbindungsleitungen der in den Figuren 3b und 5b gezeigten Anordnung entspricht,

Fig.7

eine zum Ausblasen des in den nachfolgenden Pumpräumen eventuell auftretenden Kondensats besonders vorteilhafte Anordnung der zwischen den Pumpstufen vorgesehenen Verbindungsleitungen einer in stehender Boxerform ausgebildeten Membran-Saugpumpe in einer schematischen Draufsicht sowie in einer schematischen Darstellung ihrer Pumpräume, wobei die Anordnung der Saug- und Druckventile sowie der saug- und druckseitigen Öffnungen der Verbindungsleitungen der in den Figuren 1b und 5c gezeigten Anordnung im wesentlichen entspricht,

Fig.8

eine zum Ausblasen des in den nachfolgenden Pumpräumen eventuell auftretenden Kondensats besonders vorteilhafte Anordnung der zwischen den Pumpstufen vorgesehenen Verbindungsleitungen einer in stehender Boxerform ausgebildeten Membran-Saugpumpe in einer schematischen Draufsicht (Fig.8a) und in einer schematischen Darstellung ihrer Pumpräume (Fig.5b), wobei die Anordnung der Saug- und Druckventile und der saug- und druckseitigen Öffnungen der Verbindungsleitungen der in den Figuren 2b und 5d gezeigten Anordnung entspricht,

Fig.9

eine zum Ausblasen des in den nachfolgenden Pumpräumen eventuell auftretenden Kondensats besonders vorteilhafte Anordnung der zwischen den Pumpstufen vorgesehenen Verbindungsleitungen einer in liegender Boxerform ausgebildeten Membran-Saugpumpe in einer schematischen Seitenansicht (Fig.9a) sowie in einer um 90° gedrehten schematischen Seitenansicht (Fig.9b),

Fig.10

eine mit Fig.9a und 9b vergleichbare Membran-Saugpumpe in einer schematischen Seitenansicht (Fig.10a) und in einer um 90° gedrehten Seitenansicht (Fig.10b), wobei die Pumpstufen dieser Membran-Saugpumpe über abweichend angeordnete Verbindungsleitungen miteinander verbunden sind, und

Fig.11

einen schematischen Vergleich des lichten Querschnitts der zwischen den Pumpstufen vorgesehenen Verbindungsleitungen einerseits und der zum Saugventil oder zum Druckventil führenden Ein- bzw. Auslasskanäle andererseits.

It shows:

1a

a multi-stage membrane suction pump in a schematic plan view, wherein the pumping stages of this suction pump are connected to each other via connecting lines, which have leading to the pumping chambers suction and pressure side openings,

1b shows

the membrane suction pump off 1a 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,

Figure 1C

the membrane suction pump off 1a and 1b in a schematic side view with a view of the drive motor,

2a

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

2b

the multi-stage diaphragm suction pump 2a in a schematic representation of their pumping chambers, wherein the pressure-side openings of the connecting lines in the pump chambers in comparison to the in 1b shows shown arrangement are arranged offset such that a high pumping speed is favored,

Figure 2c

the membrane suction pump off 2a and 2b in a schematic side view with a view of the drive motor,

3a

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

3b

the membrane suction pump off 3a in a schematic representation of their pump chambers, 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 the provided between the pumping stages connecting lines practically on one between the suction and the pressure valve lying line are arranged

3 c

the membrane suction pump off 3a and 3b in a schematic side view with a view of the drive motor,

Figure 4

the curve of suction pressure and suction at the in 1a to 1c . 2a to 2c and 3a to 3c illustrated diaphragm pumps,

5a

a multi-stage membrane suction pump in a schematic plan view,

5 b

a membrane suction pump in a schematic representation of their pumping rooms with a 3b comparable arrangement of the suction and pressure valves and the suction and pressure side openings of the connecting lines,

5c

a membrane suction pump in a schematic representation of their pumping rooms, wherein the arrangement of the suction and the pressure valves and the suction and pressure side openings of the connecting lines of in 1b shows corresponds to the arrangement shown,

5d

a membrane suction pump 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 in 2b corresponds to the arrangement shown,

FIG.5E

a multi-stage membrane suction pump in a side view overlooking the drive motor,

Figure 6

a particularly advantageous arrangement for blowing out the condensate possibly occurring in the subsequent pump chambers, the arrangement of the connection lines provided between the pumping stages in an upright position Boxer form trained membrane suction pump in a schematic plan view ( 6a ) and in a schematic representation of their pumping rooms ( Figure 6b ), wherein the arrangement of the pressure and suction valves and the suction and pressure side openings of the connecting lines in the FIGS. 3b and 5b corresponds to the arrangement shown,

Figure 7

a particularly advantageous for blowing out the condensate in the subsequent pumping space occurring particularly advantageous arrangement of provided between the pumping stages connecting lines formed in 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 in the Figures 1b and 5c substantially corresponds to the arrangement shown

Figure 8

a particularly advantageous arrangement for blowing out the condensate possibly occurring in the subsequent pump chambers, the connection lines provided between the pumping stages of a diaphragm suction pump formed in a stationary boxer form in a schematic plan view ( Figure 8a ) and in a schematic representation of their pumping rooms ( 5 b ), wherein the arrangement of the suction and pressure valves and the suction and pressure side openings of the connecting lines in the FIGS. 2b and 5d corresponds to the arrangement shown,

Figure 9

one 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 ( 9a ) and in a rotated by 90 ° schematic side view ( 9b )

Figure 10

one with 9a and 9b Comparable membrane suction pump in a schematic side view ( Figure 10a ) and in a 90 ° rotated side view ( 10B ), wherein the pumping stages of this membrane suction pump are connected to each other via differently arranged connecting lines, and

Figure 11

a schematic comparison of the clear cross-section of the provided between the pumping stages connecting lines on the one hand and the suction valve or the pressure valve leading inlet or outlet channels on the other.

In the FIGS. 1 to 3 and 5 to 10 Various versions of a multi-stage diaphragm suction pump 10,100 are shown. 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 in Figure 11 is indicated, the check valves provided in the inflow and outflow of the connecting lines 8,9,11 are smaller compared to the inlet and outlet valves of the pump chambers 1,2,3,4, these check valves each one open to the adjacent pumping chamber Line portion of the connecting line is associated 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 the FIGS. 3a to 3c and in 5 b pump embodiments are shown, which correspond in terms of the arrangement of leading to the connecting lines openings in the pump chamber substantially the previously known prior art. Like from the FIGS. 3b and 5b becomes clear, 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 the 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 pump designs.

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

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 the Figure 1C with the 3 c , it is clear that the arrangement of the suction-side opening of the at least one connecting line to improve the suction pressure from the center line L oriented at the top dead center transverse to the Pleuelschwenkbene out, for example, about -45 ° can be rotated in the direction of the pump chamber, in the the diaphragm associated with this pumping space first circulates during a pumping cycle. This area is in 3 c marked with "B" and "C". In contrast, from a comparison of Figures 2c and 3c clearly that to improve the pumping speed, the arrangement of the pressure-side opening of the at least one connecting line out of the top dead center transverse to Pleuelschwenkbene oriented center line L out preferably by about + 45 ° can be rotated in the direction of the pump chamber, in which this pump space associated diaphragm during a pumping cycle first rolls. 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 in the FIGS. 1 . 2 . 5c, 5d . 7.8 . 9 and 10 illustrated pump embodiments 10 by optimized with regard to their suction pressure or their pumping pump characteristics.

So is to improve the suction pressure in the in the FIGS. 1 . 5c . 7 . 9 and 10 pump embodiments shown, the suction-side opening 12 of the at least one connecting line 8,9,11 arranged in the region of the pump chamber or approximated to this area at which the diaphragm associated with this pumping space first rolls during a pumping cycle. The suction-side opening 12 is thus offset from the pump longitudinal center plane preferably approximately at 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 membrane facing this pump chamber a pumping cycle first rolls.

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 in the Figures 2 . 5d and 8th pump designs shown should instead be improved, the pumping speed. 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.

In Figure 4 is also the curve of suction pressure and suction at the in the FIGS. 1 . 5c . 7 . 9 and 10 Pump versions shown on the one hand and in the in the Figures 2 . 5d and 8th on the other hand shown pump versions. While the curve marked "-45 ° / + 45 °" in the FIGS. 1 . 5c . 7 . 9 and 10 shows pump versions characterized by an improved, namely additionally reduced suction pressure, the marked with "+ 45 ° / -45 °" curve of the in the Figures 2 . 5d and 8th Pump designs shown on an improved pumping speed.

As if from a comparison of FIGS. 1 . 2 . 3 . 5c . 5d . 7 . 8th . 9 and 10 becomes clear, the pressure or the suction-side openings 12,13 of the at least one connecting line 8,9,11 and the suction valve provided in the fluid inlet 6 are 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 due to the re-expansion of the condensate, the final pressure can not be achieved.

In the in the FIGS. 6 to 10 Pump versions shown is at least one connecting line 8,9,10 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 if from a comparison of Figures 9 and 10 becomes clear, located in the mounted on both sides of the pump housing heads suction side 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 is deflected in the upward direction by the tilting movement in the direction of rotation, be arranged if one seeks to optimize the suction curve with respect to the 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 connecting line is created.

If the boxer pump described above in contrast - as in the FIGS. 6 to 8 shown - operated in a stationary position, the connecting line 8 between the second and the third pumping stage 2,3 is arranged horizontally, while the connecting line 9 between the third and the fourth pumping stage 3,4 is arranged to fall. An embodiment is preferred in which the suction-side opening 12 of the connecting line provided in the second pumping stage 2 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 ( Fig. 7b, 8b ) is arranged.

In FIG. 11 schematically illustrates that the cross section d of the connecting lines 8, 9, 11 should be designed between the comparatively small designed check valves so that the gas velocity occurring therein 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 pressure or suction valves leading to the pressure or suction valves. Thus, the lowest effective gas velocity is achieved with falling or horizontal arrangement of the connecting lines 8, 9, 11.

Claims (12)

1. Multi-stage diaphragm suction pump (10), comprising at least two pump chambers (1, 2, 3, 4), each having a diaphragm which is driven by a connecting rod of a crank mechanism and rolls on a pump chamber wall, and each having a fluid inlet (6) having at least one inlet valve, and a fluid outlet (7) having at least one outlet valve, and comprising a suction line, which connects the fluid inlets (6) of the pump chambers (1, 2, 3, 4), wherein successive pump chambers (1, 2, 3, 4) are each connected to one another by means of at least one connection line (8, 9, 11) in such a way that, when a differential pressure in the suction line is reached/exceeded, the diaphragm pump (10) changes from parallel operation of the pump chambers (1, 2, 3, 4) thereof to an operating mode of said pump chambers that is at least also serial, and wherein 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 (8, 9, 11), characterized in that, either, in order to improve the intake pressure, the suction-side opening (12) of the at least one connection line (8, 9, 11) or, in order to improve the suction capacity, the pressure-side opening (13) of the at least one connection line (8, 9, 11) at least in one pump chamber (1, 2, 3, 4) is arranged offset out of the pump longitudinal centre plane in the hemisphere of the pump chamber (1, 2, 3, 4) on which the diaphragm associated with said pump chamber rolls first during a pump cycle.
2. Diaphragm suction pump according to Claim 1, characterized in that a connecting rod that can be pivoted in a connecting rod oscillation plane is assigned to each pump chamber (1, 2, 3, 4) of the diaphragm pump (10), and in that, at least in one pump chamber (1, 2, 3, 4), the suction-side or the pressure-side opening (12, 13) of at least one connection line (8, 9, 11) is provided in the connecting rod oscillation plane.
3. Diaphragm 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 connection line (8, 9, 11) is arranged in the edge region of the pump chamber (1, 2, 3, 4), which adjoins the clamping zone of the diaphragm.
4. Diaphragm suction pump according to one of Claims 1 to 3, characterized in that, at least in one pump chamber (1, 2, 3, 4), the suction-side or the pressure-side opening (12, 13) of the at least one connection line (8, 9, 11) and the suction valve are arranged approximately on a line extending transversely to the connecting rod oscillation plane.
5. Diaphragm suction pump according to one of Claims 1 to 4, characterized in that, in order to improve the intake pressure, the suction-side opening (12) of the at least one connection line at least in the pump chamber (2) of the second pump stage in the delivery direction is arranged in the region of the pump chamber (2), or in the vicinity of the region of the pump chamber (2), on which the diaphragm associated with said pump chamber rolls first during a pump cycle.
6. Diaphragm suction pump according to one of Claims 1 to 4, characterized in that, in order to improve the suction capacity, the pressure-side opening (13) of the at least one connection line at least in the pump chamber (1) of the first pump stage in the delivery direction is arranged in the region of the pump chamber (1), or in the vicinity of the region of the pump chamber (1), on which the diaphragm associated with said pump chamber rolls first during a pump cycle.
7. Diaphragm suction pump according to one of Claims 1 to 6, characterized in that at least one connection line (8, 9, 11), in particular between successive pump chambers (1, 2, 3, 4), has a descending line progression and in that, for this purpose, the inflow-side line segment of said at least one connection line (8, 9, 11) is arranged at a higher level in comparison with the outflow-side line segment.
8. Diaphragm suction pump according to one of Claims 1 to 7, characterized in that the pump stages (1, 2, 3, 4) of the multi-stage diaphragm pump (10, 100) are arranged in pairs in an opposed configuration.
9. Diaphragm suction pump according to one of Claims 1 to 8, characterized in that the suction-side opening (12) of the connection line (9) provided in the second pump stage (2) is arranged above the crank axis and/or the pressure-side opening (13) of the connection line provided in the third pump stage (3) is arranged below the crank axis.
10. Diaphragm suction pump according to one of Claims 1 to 9, characterized in that the connection lines (8, 9, 11) 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.
11. Diaphragm suction pump according to one of Claims 1 to 10, characterized in that the diaphragm suction pump (10, 100) has four pump chambers (1, 2, 3, 4).
12. Diaphragm suction pump according to one of Claims 1 to 11, characterized in that at least one suction- or pressure-side opening of a connection line is provided in the first and in the last pump chamber (1, 4) of the successive pump chambers (1, 2, 3, 4), and at least one suction- and at least one pressure-side opening of the connection lines are provided in the pump chambers (2, 3) arranged therebetween.

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