Rotary lobe pump for use in potentially explosive atmospheres

Abstract

The invention relates to a rotary lobe pump comprising a pump chamber with a pump inlet opening and a pump outlet opening and a first pump rotary lobe rotatably mounted within the pump chamber, a drive chamber with a drive inlet opening, a drive outlet opening and a first drive rotary lobe rotatably mounted within the drive chamber, characterized by a first pump drive shaft rotatably mounted about a first shaft axis, on which the first pump rotary lobe and the first drive rotary lobe are torque-resistant attached, and a housing sealed against the environment, within which the pump chamber and the drive chamber are arranged and the first pump drive shaft is arranged and mounted.

Description

[0001] The invention relates to a rotary lobe pump, comprising a pump chamber with a pump inlet opening and a pump outlet opening, and a first pump rotary lobe rotatably mounted within the pump chamber, a drive chamber with a drive inlet opening, a drive outlet opening, and a first drive rotary lobe rotatably mounted within the drive chamber. A further aspect is a method for operating a rotary lobe pump.

[0002] Rotary lobe pumps are positive displacement pumps and pump a fluid by displacement using a pair of multi-lobe rotary lobes. These two rotary lobes are arranged in a pumping chamber and rotate in opposite directions around two parallel axes. Between the two axes, the rotary lobes mesh with each other in such a way that a piston lobe of one rotary lobe engages between two piston lobes of the other rotary lobe. In the area between the two axes of rotation, the rotary lobes are in permanent sealed contact with each other - possibly with a small leakage gap - and the fluid is pumped via the circumferential area lying outside the two axes of rotation in the spaces between the piston lobes of the two rotary lobes from an inlet opening to an outlet opening of the pumping chamber.

[0003] It is known to drive such rotary lobe pumps using electric motors, combustion engines, or hydraulic motors. These motors are flanged externally to the rotary lobe pump and often drive one of the two rotary lobes. In rotary lobe pumps, the other rotary lobe is driven by a separate gear, which synchronizes the two shafts on which the rotary lobes rotate. Furthermore, EP 1519044 B1 and WO2014 / 067988A2 disclose setting both rotary lobes in rotation using separate drives and synchronizing this rotation by appropriately controlling the drives or by the synchronization effect of the two meshing rotary lobes.In these previously known solutions, the intermeshing rotary pistons are arranged in a pump housing and fastened to rotatably mounted shafts, and the shafts are sealed out of the housing and connected to the corresponding drive shafts of the drive motors via couplings.

[0004] Rotary lobe pumps of this design are used in a wide variety of applications. Due to the heavy weight of such rotary lobe pumps, which is often a result of their design, they are typically used in stationary applications. For use in potentially explosive environments, it is common practice to locate the drive motor of a rotary lobe pump outside the potentially explosive environment and transfer the drive power to the rotary lobes via a long transmission shaft or other transmission mechanism. While this design makes it possible to use rotary lobe pumps in potentially explosive environments, it often increases their weight even further.

[0005] DE 202007005404 U1 discloses a rotary lobe pump with an electric drive. The drive transmits the drive force to a pulley via an endless belt. The pulley is mounted outside the pump housing on a shaft extending through the pump housing, ensuring a torque-resistant connection. The rotary lobe pump is mounted in a transport frame together with the electric drive motor and a battery. The disadvantages of this arrangement are that it is maintenance-intensive and, on the other hand, heavy, making it difficult to transport without the help of several people.

[0006] There is therefore a need for a rotary lobe pump that can be used in potentially explosive environments and is easily transportable. The invention is based on the object of providing such a rotary lobe pump.

[0007] The invention solves this problem by a rotary piston pump of the type mentioned at the outset, which is characterized by a first pump drive shaft which is mounted rotatably about a first shaft axis and on which the first pump rotary piston and the first drive rotary piston are fastened in a torque-resistant manner, and a housing which is sealed off from the environment and within which the pump chamber and the drive chamber are arranged and the first pump drive shaft is arranged and mounted.

[0008] The rotary lobe pump according to the invention is characterized by a housing that accommodates both a pumping chamber and a drive chamber. The pumping chamber is understood to be the sealed space within the housing through which the liquid to be pumped is conveyed by means of the pumping rotary lobes. The drive chamber is understood to be the sealed space arranged within the housing, within which a first drive rotary lobe is arranged. This drive rotary lobe is set in rotation by a fluid that flows with a pressure difference through the drive chamber from the drive inlet opening to the drive outlet opening. The first drive rotary lobe is connected to the first pumping rotary lobe in a torque-fixed manner via the first pump drive shaft and therefore transfers the torque acting on it to the first pumping rotary lobe, consequently setting it in rotation.

[0009] By arranging the drive chamber in an integrally constructed housing, the invention achieves a structurally efficient sealing option between the drive chamber and the pump chamber, both of which are pressurized, thus enabling the seal required for sealing the pump drive shaft to operate long-lasting and economically. The pump drive shaft is arranged and supported entirely within the housing and extends from the drive chamber into the pump chamber without the need for a flange connection to connect two shafts. In particular, both the pump rotary piston and the drive rotary piston can be mounted on the same pump drive shaft.

[0010] This simplified design of the pump drive shaft and the seal simultaneously enables very compact dimensioning and a very secure and permanent sealing of the housing, so that the rotary lobe pump according to the invention can be designed with low weight and high performance and is therefore easy to transport by one or two people for typical applications, for example in the field of fire brigade equipment and disaster control, and can be accommodated in the equipment compartment of an emergency vehicle.

[0011] It should be understood that both the pumping chamber and the drive chamber typically contain two pumping rotary pistons or driving rotary pistons, which interact in a sealed manner according to the principle of a rotary piston pump, thereby achieving the pumping effect in the pumping chamber, as previously described. With a correspondingly inverse function in the drive chamber, the two driving rotary pistons are set in rotation in the manner of a fluid-driven motor by a pressure difference of a fluid from the drive inlet opening to the drive outlet opening. At least the first driving rotary piston is connected to the first pumping rotary piston via the first pump drive shaft in order to transmit this drive force.In principle, sufficient transmission of the drive force can be achieved in such a case by meshing them together, and the second drive rotary piston and the second pump rotary piston do not need to be directly coupled to each other for rotation and transmission. In advantageous embodiments, however, the second pump rotary piston and the second drive rotary piston are also connected to each other by a second pump drive shaft, so that each of the pump rotary pistons in the pump chamber is directly driven by a corresponding drive rotary piston.

[0012] A housing sealed from the environment is understood in particular to mean a housing that is sealed by a corresponding housing design with closed covers and static seals, whereby a static seal is understood to be a seal that acts between two parts that are not moving relative to one another, such as a pinch seal in the manner of an O-ring, a paper seal, or a sealing compound. The housing sealed from the environment particularly preferably has no feedthroughs for a drive shaft or the like and is thus advantageously designed compared to the prior art, since it is particularly reliably and permanently sealed from the environment due to the omission of seals between moving parts.

[0013] According to a first preferred embodiment, the housing completely encloses the first pump drive shaft. According to this embodiment, the first pump drive shaft is arranged entirely within the housing and thus does not protrude from the housing, for example, to enable connection to a drive motor.

[0014] It is even more preferred if the first pump drive shaft is mounted at a first shaft end of the pump drive shaft within the housing for rotation about the shaft axis, and a second shaft end opposite the first shaft end is arranged freely within the housing. According to this embodiment, the pump drive shaft is rotatably mounted at one end, which can be achieved, for example, by being supported by two rolling bearings or two plain bearings, or a combination of plain and rolling bearings, and the other end of the pump drive shaft is freely mounted, which is understood to mean a non-bearing-supported shaft end arrangement.This free-floating arrangement of the second end of the pump drive shaft allows the rotary lobe pump to be designed for particularly easy maintenance. The housing is closed by a removable cover in the area of ​​the second shaft end. This cover allows the pump rotary lobes to be removed from the pump drive shafts without requiring the disassembly of a bearing. It should be understood that this design is preferably implemented for both pump drive shafts and both pump rotary lobes.

[0015] It is even further preferred if a first shaft seal is arranged around the first pump drive shaft between the pump chamber and the drive chamber. According to this embodiment, the pump chamber and the drive chamber are sealed from one another by means of a shaft seal around the first pump drive shaft. In the same way, a second pump drive shaft could also be sealed by a corresponding second shaft seal, thereby effectively preventing the transfer of fluid from the drive chamber into the pump chamber. It should be understood that this shaft seal is intended to withstand the pressure difference between the pump chamber and the drive chamber and preferably prevent any transfer of fluid.In embodiments in which the drive chamber is flowed through by a fluid whose admixture with the pumping fluid is harmless, for example because the drive chamber is flowed through by water, such a special shaft seal can be dispensed with and a transfer of fluid through an annular gap can be accepted or the shaft seal can also be designed as a seal with leakage and as a result a permanent passage of fluid from the drive chamber into the pumping chamber, which lubricates the seal.

[0016] It is further preferred if, in the pump chamber, a second pump rotary piston, which interacts with the first pump rotary piston, is arranged so as to rotate about a second pump shaft, and if, in the drive chamber, a second drive rotary piston, which interacts with the first drive rotary piston, is arranged so as to rotate about a second drive shaft. According to this embodiment, the pump chamber and drive chamber are each equipped with two pump rotary pistons and drive rotary pistons, respectively, which rotate in opposite directions in a sealed, meshing engagement with one another. The second drive rotary piston is arranged on a second drive shaft, which is rotatably mounted, and the second pump rotary piston is arranged on a second pump shaft, which is rotatably mounted, and this second pump shaft and this second drive shaft can be designed to rotate independently of one another.

[0017] In this embodiment, it is particularly preferred if the second pump shaft and the second drive shaft are designed as an integral second pump drive shaft, and a second shaft seal is preferably arranged around the second pump drive shaft between the pump chamber and the drive chamber. In this embodiment, the second pump shaft and the second drive shaft are designed integrally as a second pump drive shaft, such that the drive force acting on the second drive rotary piston is transmitted to the second pump rotary piston. Consequently, both pump rotary pistons are driven directly via the respective drive rotary pistons through a correspondingly direct torque transmission via two pump drive shafts, such that a high-torque and low-wear drive from the drive chamber into the pump chamber takes place.

[0018] It is even further preferred if the pump outlet opening and the drive outlet opening open into a common pump drive outlet opening, preferably within the housing. In principle, the pump inlet and outlet opening and the drive inlet and outlet opening can be designed separately from one another directly on the housing, so that the fluid supplied to the drive chamber and the fluid supplied to the pump chamber can be guided through the housing in a media-separated manner. According to this preferred embodiment, however, it is provided that the pump outlet opening and the drive outlet opening open into a common pump drive outlet opening and consequently the fluid flowing out of the drive chamber and the fluid flowing out of the pump chamber are combined and preferably guided out of the housing together.In many applications where the drive chamber is flowed through by a fluid that can be safely mixed with the pumped liquid, this is advantageous for simplified construction and connection of the rotary lobe pump according to the invention. It can also effectively increase the pumped fluid volume on the outlet side. This is an advantageous mode of operation of the rotary lobe pump according to the invention, for example, when filling a container with a high volume flow is intended.

[0019] In a further development of this, a valve is provided within the housing or on the housing, which in a first position connects the drive outlet opening with the pump drive outlet opening and in a second position separates this connection and instead connects the drive outlet opening with a separate outlet opening formed on the housing for the drive fluid. With this development, it is possible to switch back and forth between separate guidance of the media and a merging of the media. Such a valve can be designed as a structurally simple solution by a removable partition in a container or in the housing, which separates the fluid flow from the pump outlet opening and the fluid flow from the drive outlet opening.

[0020] It is even further preferred if the first and optionally second pump drive shaft is rotatably mounted within the housing in a bearing cooled by the drive fluid flowing from the drive inlet opening to the drive outlet opening, in particular if the bearing comprises a bearing housing which is at least partially surrounded by a cooling channel. The cooling channel is preferably connected in series with the drive chamber and can alternatively be arranged on the positive or negative pressure side of the drive chamber. According to this embodiment, the fluid flowing through the drive chamber simultaneously cools a bearing of the first pump drive shaft and, if present, the second pump drive shaft, in that this fluid is guided around or through such a bearing. This flow around or through can take place before entering the drive chamber or after exiting the drive chamber.This development prevents overheating of the bearings and allows the pump to operate with thermal stability under high loads.

[0021] It is even further preferred if the housing is designed for installation in an operating position in which the first shaft axis and optionally the second shaft axis are aligned parallel to the direction of gravity and the pump chamber is arranged above the drive chamber. According to this embodiment, the rotary lobe pump is aligned in the operating position with vertical shaft axes and the pump chamber is arranged above the drive chamber. This embodiment is particularly advantageous when the pump drive shaft is mounted on one side, since a bending force acting on the pump drive shaft due to gravity is avoided. At the same time, the arrangement prevents fluid from passing from the drive chamber into the pump chamber due to gravity when the pump is at a standstill, thus preventing contamination of the pumped fluid by the drive fluid.This design is therefore particularly advantageous for the conveyance of hazardous fluids.

[0022] According to a further preferred embodiment, the housing does not have any passage for one or more rotating shafts transmitting a drive force. By completely eliminating the passage of drive force-transmitting shafts, the sealing of the housing is both structurally simplified and made particularly reliable, allowing a compact housing design to be realized. Consequently, in this embodiment, the housing can be sealed solely by static seals acting between components that do not move relative to one another.

[0023] The rotary lobe pump according to the invention can be further developed by a reservoir chamber arranged in front of the pump inlet for storing fluid, comprising a reservoir chamber inlet and a reservoir chamber outlet connected to the pump inlet, which, in the operating position of the pump, is located below the reservoir chamber inlet in the direction of gravity. Such a reservoir chamber maintains a fluid supply at the rotary lobe pump, which, after a shutdown process, immediately supplies the pump chamber with fluid upon restarting the pump, thereby increasing the dry-running safety of the rotary lobe pump.

[0024] Finally, it is even more preferred to further develop the rotary lobe pump according to the invention by a support frame surrounding the pump housing, which preferably comprises support points or lines that define a support surface on a flat plane that is spaced from the housing, wherein the support frame preferably defines a plurality of such support surfaces that are spaced from the housing in one, two, or all three spatial axes. Such a support frame protects the housing from damage in the operating position or preferably any other installation position and can simultaneously serve as handles for transporting the pump by one or two people.

[0025] A further aspect of the invention is a method for operating a rotary lobe pump, in particular in potentially explosive environments, comprising the steps: Supplying a drive fluid through a drive inlet opening into a drive chamber, discharging the drive fluid through a drive outlet opening from the drive chamber and driving a first drive rotary piston in the drive chamber into a rotational movement by means of a pressure difference in the drive fluid prevailing from the drive inlet opening to the drive outlet opening,

[0026] Transferring the rotational movement by means of a pump drive shaft to a first pump rotary piston rotatably mounted within a pump chamber,

[0027] Pumping a pump fluid from a pump inlet opening through the pump chamber to a pump outlet opening by means of the displacement effect of the rotating first pump rotary piston, which is characterized in that the drive chamber, the pump chamber, and the pump drive shaft are arranged within a housing and sealed from the environment. This method according to the invention is characterized by a flow through a pump chamber and a drive chamber with a corresponding fluid to be pumped and a corresponding drive fluid, both of which are arranged within a housing and sealed from the environment. The method according to the invention therefore dispenses with transmitting the drive force from a first housing via a drive shaft to a second housing and sealing the shafts required for the transmission from the environment with corresponding shaft seals on the first housing and on the second housing and connecting them to one another in a torque-resistant manner via a corresponding shaft coupling.Instead, the pump drive shaft is an integral shaft used to transmit the rotary motion, arranged within an integral housing and supporting both the pumping rotary piston and the drive rotary piston. It can be sealed using a simple gasket so that the pumping chamber and drive chamber are sealed from each other.

[0028] In the process according to the invention, it is particularly preferred if water is supplied as the drive fluid. Water is a readily available, incompressible, and environmentally safe medium, and can therefore be used advantageously as a drive fluid with minimal safety and sealing precautions.

[0029] It is particularly preferred if the drive fluid and the pump fluid are combined in the flow direction downstream of the drive outlet opening and the pump outlet opening, preferably within the housing. The combination of the drive fluid and the pump fluid can preferably be achieved if water is used as the drive fluid. This combination simplifies the design and connection of the pump used for the process, while also effectively increasing the pumped output volume, thus achieving a high volumetric flow rate.

[0030] It is even more preferred if the drive fluid and / or the pump fluid flow around a bearing unit for rotatably supporting the pump drive shaft within the housing, thereby cooling it. According to this embodiment, one of the fluids flowing through the housing causes cooling of a bearing unit, thereby increasing the thermal stability of the pumping method according to the invention.

[0031] Finally, it is even more preferred if the drive fluid and the pump fluid are sealed from the environment within the housing by means of static seals, and the housing does not have a passage through which one or more rotating shafts transmit a drive force extend. By eliminating the passage of a rotating shaft transmitting a drive force, in particular a shaft rotating in the same direction as a rotary piston, from the housing, dynamic seals between moving parts are eliminated, thus achieving a housing design that is both structurally simple and particularly reliably sealed.

[0032] The pump inlet and outlet ports can be fluidly connected to an inlet nozzle and outlet nozzle, respectively, and the drive inlet and outlet ports can be fluidly connected to corresponding drive inlet and outlet nozzles. The respective nozzles can have different couplings for connecting a pipe or hose, thus ensuring a secure connection when commissioning the rotary lobe pump.

[0033] In a preferred embodiment, however, the two inlet ports for the pump chamber and drive chamber can also be provided with matching couplings and, accordingly, the outlet ports for the pump chamber and drive chamber can also be provided with matching couplings. This enables operation in two different modes. In the first mode, the pump chamber serves to pump the liquid and the drive chamber acts as a motor chamber to generate the torque for the pumping action in the pump chamber. In the other mode, these functions are reversed, so that the pumping action is generated by the drive chamber and the drive action by the pump chamber. This interchangeability is particularly advantageous when the pump chamber and the drive chamber have different delivery volumes per revolution.With such a design, one mode of operation can achieve a high volume flow rate per revolution with a necessary high pressure difference across the chamber serving as the drive chamber, while the other mode of operation achieves a lower flow rate per revolution with a necessary lower pressure difference between inlet and outlet on the chamber side of the pump serving as the drive chamber.

[0034] A preferred embodiment of the invention is explained with reference to the accompanying figures. They show: Fig. 1 a perspective view of the rotary lobe pump according to the invention, Fig. 2 a perspective view according to Fig. 1 with a support frame arranged around the rotary lobe pump, Fig. 3 a side view of the rotary piston pump according to the invention, Fig. 4 one along the line AA in Fig. 3 longitudinal section front view of the rotary piston pump according to the invention, and Fig. 5 one along the line BB in Fig. 3 cross-sectional top view of the rotary lobe pump according to the invention.

[0035] Referring first to Fig. 1, a rotary lobe pump according to the invention has a housing 10 which encloses a pumping chamber in an upper housing section 11 (located at the top in the figure) and a drive chamber in a lower housing section 12 located thereunder. The housing section 11 is closed with a pumping chamber cover on its upper side. Arranged below the housing section 12 is a bearing housing 15 with a base 15' located below, which forms a lower housing cover. The housing sections 11, 12, and 15, as well as the pumping chamber cover 17 and the base 15', essentially form the housing 10 of the rotary lobe pump integrally and can be directly connected to one another, for example, by flange connections 13, 13'.This integral design of the housing consequently avoids the need to pass a rotating drive shaft into the surrounding area, with which the drive force from a drive must be transmitted to the pump pistons in the housing section of the pump chamber.

[0036] In the area of ​​the housing section 11, a pump inlet pre-chamber 20 is arranged on the side, into which a pump inlet nozzle 21 opens. The pump inlet pre-chamber 20 has a cover 28 attached to the side. This cover is pre-assembled by means of several screws or bolts 29, which can preferably be welded to the pump inlet pre-chamber for reliable sealing and fastening. The screws 29 extend through the interior of the pump inlet pre-chamber 20 and simultaneously divide this interior into an inlet area, into which the pump inlet nozzle 21 opens, and an outlet area, from which the pump chamber draws fluid. Depending on the distance between them, the screws 29 can thus prevent larger solids from entering the pump chamber, while at the same time, such solids can be easily removed from the pump inlet pre-chamber by dismantling the cover 28.

[0037] Similarly, opposite the pump inlet pre-feed chamber, a pump outlet pre-feed chamber 30a is arranged, extending over a portion of the housing section 11. The pump outlet pre-feed chamber has a pump outlet connection 32. Furthermore, in a lower region, a section formed as a drive outlet pre-feed chamber 30b is arranged, on which a drive outlet connection 34 is arranged.

[0038] Finally, a drive inlet nozzle 14 is formed in the bearing housing 15.

[0039] Fig. 2 shows the rotary lobe pump according to Fig. 1 is mounted in a support frame 40. The support frame 40 comprises two lateral frame sections 41a, b consisting of bent tubes, which are connected to one another by several tubular struts 42a, b, c. The rotary lobe pump is mounted on two of these cross struts 42a, b by means of the base 15' formed on the bearing housing 15.

[0040] The support frame 40 surrounds the rotary lobe pump in such a way that, when viewed in all three spatial axes, its outline projects beyond the rotary lobe pump, so that when the rotary lobe pump is placed on a flat surface in the operating position shown, the rotary lobe pump itself does not come into contact with the flat support surface, and such contact cannot occur if the rotary lobe pump is lying on its side or upside down. In particular, the support frame 40 can comply with, and preferably exceed, the dimensions permitted in DIN 14427 for explosion-proof, portable hazardous material transfer pumps. Due to the design according to the invention, the maximum weight of 100 kg specified in this standard is significantly exceeded by the rotary lobe pump according to the invention. In particular, the rotary lobe pump according to the invention, including the support frame, can weigh less than 75 kg.

[0041] With reference to the Fig. Figures 3 to 5 explain in more detail the structure of the rotary lobe pump within the housing 10 and the two supply chambers 20, 30. The rotary lobe pump has a bearing 50 in the lower housing section 12 with a bearing housing 51 and two rolling bearings 52, 53 arranged therein. This bearing provides a rotatable support for a first drive pump shaft 60a about a first shaft axis 60a'. It should be understood that a second drive pump shaft 60b is mounted in the same manner, parallel and spaced apart, in the bearing housing 51 for rotation about a second shaft axis 60b'.

[0042] The bearing housing 51 is surrounded by and sealed from a drive fluid inlet chamber 16, through which the drive fluid flows from the drive inlet port 14. The drive fluid thereby cools the bearing 50 before flowing through a drive inlet opening 71 into a drive chamber 70. The drive chamber 70 is arranged above the bearing 50 and has two drive rotary pistons 72a, b, which are torque-tightly mounted on the two drive pump shafts 60a, b. The two drive rotary pistons 72a, b are set into counter-rotation by the drive fluid flowing from the drive inlet opening 71 to a drive outlet opening 73, and they transmit this counter-rotation to the two drive pump shafts 60a, b.

[0043] The pump inlet connection 21 opens into the pump inlet storage chamber 20, and the fluid sucked in by the rotary lobe pump through the pump inlet connection 21 is sucked from the pump inlet storage chamber 20 into a pump chamber 80 through a pump inlet opening 81. This suction process is generated by two pairs of intermeshing pump rotary lobes 82a, b, 83a, b; in principle, these two pairs can also be formed by a single pair of intermeshing pump rotary lobes or by more than two such pairs. The pump rotary lobes 82a, 83a are torque-tightly attached to the drive pump shaft 60a, and the pump rotary lobes 82b, 83b are torque-tightly attached to the pump drive shaft 60b.The pump rotary pistons are set in rotation by the drive rotary pistons via the pump drive shafts and thereby cause the pump fluid to be conveyed from the pump inlet opening to a pump outlet opening 84, through which the pumped fluid is conveyed into the pump outlet storage chamber 30 and from there discharged through the pump outlet connection.

[0044] As is particularly evident from Fig.4, a partition wall 85 separates the pump outlet supply chamber 30a from the drive outlet supply chamber 30b, wherein the upper section 30a is flowed through by the fluid conveyed through the pump chamber and the lower section 30b is flowed through by the fluid conveyed through the drive chamber, which flows from this lower section to the drive outlet connection 32. This partition wall 35 is detachably attached and could also be removed or designed as a switchable valve to allow the fluid flows emerging from the pump chamber and the drive chamber to be combined and discharged through a single one of the two outlet connections 34, 32. The corresponding other outlet connection can be closed in such a case and is not used.

[0045] At the upper end, the housing 10 has the pump chamber cover 17, which closes the housing by means of static seals. Similarly, at the lower end of the housing, the base 15' is designed as a lower cover, which seals the housing at the bottom with static seals. The upper pump chamber cover 17 is detachably connected, in the exemplary embodiment by means of a screw connection, which can be loosened to allow the pumping rotary pistons in the pump chamber to be replaced when they become worn.

[0046] A flange 18 is arranged within the housing between the drive chamber and the pump chamber, through which the two pump drive shafts 60a, b pass and are sealed by corresponding shaft seals 19 to prevent fluid from passing between the pump chamber and the drive chamber. Similarly, a flange 75 is arranged between the drive chamber and the bearing 50 in the housing, through which both pump drive shafts 60a, b pass and are sealed by corresponding shaft seals 76 to prevent drive fluid from passing from the drive chamber 70 into the bearing or vice versa.

[0047] The drive rotary pistons and pump rotary pistons can be designed as rotary pistons with straight rotary piston vanes, in which the rotary piston vanes extend in a straight line parallel to the shaft axis 60a' or 60b'. Preferably, and in the exemplary embodiment shown, the pump rotary pistons and drive rotary pistons are designed with inclined rotary piston vanes, in which the rotary piston vanes extend along a helical line around the shaft axes 60a', 60b'. The drive rotary pistons and pump rotary pistons can preferably run inclined in such a way that, by following the course of the thread pitch, the pump rotary pistons and drive rotary pistons seated on a shaft achieve a balance of the axial forces acting on the bearing due to this thread pitch and, if necessary, other axial forces, such as compressive forces acting on end surfaces.For example, if both pump rotary pistons and the drive piston have the same length and a thread pitch that matches both in magnitude and direction, the axial forces acting on the drive side and pump side due to the fluid pressure can be canceled out – the increased pressure in the drive chamber compensates for the greater rotary piston length in the pump chamber. In this way, the bearing 50 can be relieved of load and thus operated economically efficiently, absorbing only the circumferential and bending forces that occur during operation of the rotary piston pump. QUOTES CONTAINED IN THE DESCRIPTION

[0000] This list of documents submitted by the applicant was generated automatically and is included solely for the convenience of the reader. This list is not part of the German patent or utility model application. The DPMA assumes no liability for any errors or omissions. Cited patent literature

[0000] EP 1519044 B1

[0003] WO 2014 / 067988A2

[0003] DE 202007005404 U1

[0005]

Claims

[1] Rotary lobe pump, comprising - a pump chamber with a pump inlet opening and a pump outlet opening and a first pump rotary piston rotatably mounted within the pump chamber, - a drive chamber with a drive inlet opening, a drive outlet opening and a first drive rotary piston rotatably mounted within the drive chamber, characterized by a first pump drive shaft rotatably mounted about a first shaft axis, on which the first pump rotary piston and the first drive rotary piston are fixed in a torque-resistant manner, and a housing sealed against the environment, within which the pump chamber and the drive chamber are arranged and within which the first pump drive shaft is arranged and supported. [2] Rotary piston pump according to claim 1, characterized by that the housing completely encloses the first pump drive shaft. [3] Rotary piston pump according to claim 1 or 2, characterized bythat the first pump drive shaft is mounted at a first shaft end of the pump drive shaft within the housing so as to be rotatable about the shaft axis and a second shaft end opposite the first shaft end is arranged freely in the housing. [4] Rotary piston pump according to one of the preceding claims, characterized by that a first shaft seal is arranged around the first pump drive shaft between the pump chamber and the drive chamber. [5] Rotary piston pump according to one of the preceding claims, characterized by that in the pump chamber a second pump rotary piston cooperating with the first pump rotary piston is arranged rotatably about a second pump shaft and in the drive chamber a second drive rotary piston cooperating with the first drive rotary piston is arranged rotatably about a second drive shaft. [6] Rotary piston pump according to claim 5, characterized bythat the second pump shaft and the second drive shaft are formed as an integral second pump drive shaft and preferably a second shaft seal is arranged around the second pump drive shaft between the pump chamber and the drive chamber. [7] Rotary piston pump according to one of the preceding claims, characterized by that the pump outlet opening and the drive outlet opening open into a common pump drive outlet opening, preferably within the housing. [8] Rotary piston pump according to one of the preceding claims, characterized bythat the first and optionally second pump drive shaft is rotatably mounted within the housing in a bearing cooled by the drive fluid flowing from the drive inlet opening to the drive outlet opening, in particular in that the bearing comprises a bearing housing which is at least partially surrounded by a cooling channel which is preferably connected in series with the drive chamber on its overpressure side or on its underpressure side. [9] Rotary piston pump according to one of the preceding claims, characterized by that the housing is designed for installation in an operating position in which the first shaft axis and, if applicable, the second shaft axis are aligned parallel to the direction of gravity and the pump chamber is arranged above the drive chamber. [10] Rotary piston pump according to one of the preceding claims, characterized bythat the housing does not have a passage for one or more shafts transmitting a driving force. [11] Rotary piston pump according to one of the preceding claims, characterized by a storage chamber arranged in front of the pump inlet opening for storing liquid, having a storage chamber inlet opening and a storage chamber outlet opening connected to the pump inlet opening, which in the operating position of the pump lies below the storage chamber inlet opening in the direction of gravity. [12] Rotary piston pump according to one of the preceding claims, characterized by a support frame surrounding the pump housing, which preferably comprises support points or lines that define a support surface on a flat plane that is spaced from the housing, wherein the support frame preferably defines a plurality of such support surfaces that are spaced from the housing in one, two or all three spatial axis directions. [13] Method for operating a rotary lobe pump, in particular in an explosive environment, comprising the steps: • Supplying a drive fluid through a drive inlet opening into a drive chamber, discharging the drive fluid through a drive outlet opening from the drive chamber and driving a first drive rotary piston in the drive chamber into a rotational movement by means of a pressure difference in the drive fluid prevailing from the drive inlet opening to the drive outlet opening, • Transferring the rotational movement by means of a pump drive shaft to a first pump rotary piston rotatably mounted within a pump chamber, • Pumping a pump fluid from a pump inlet opening through the pump chamber to a pump outlet opening by means of the displacement effect of the rotating first pump rotary piston, characterized bythat the drive chamber, the pump chamber and the pump drive shaft are arranged within a housing and sealed from the environment. [14] Method according to claim 13, characterized by that water is supplied as the driving fluid. [15] Method according to claim 13 or 14, characterized by that the drive fluid and the pump fluid are brought together in the flow direction behind the drive outlet opening and the pump outlet opening, preferably within the housing. [16] Method according to one of claims 13 to 15, characterized by that the drive fluid and / or the pump fluid flow around a bearing unit within the housing for the rotatable mounting of the pump drive shaft and thereby cool it. [17] Method according to one of claims 13 to 16, characterized bythat the drive fluid and the pump fluid within the housing are sealed against the environment by means of static seals and that the housing does not have a leadthrough for one or more co-rotating shafts transmitting a drive force.

Images