FLUID PROMOTION DEVICE

Description

[0001] The invention relates to a fluid conveying device with a backing pump and a main pump fluidically connected to the backing pump, wherein the backing pump is drivable via a backing pump input shaft and the main pump via a main pump input shaft and the backing pump input shaft and the main pump input shaft are mechanically coupled to a common drive shaft of the fluid conveying device, wherein the main pump is designed as an at least partially compensated internal gear pump.

[0002] For example, DE 10 2007 032 103 A1 is known from the prior art. This relates to a pump unit with a main pump and a boost pump with adjustable delivery volume. A cam ring is provided to adjust the delivery volume of the boost pump. The cam ring is subjected to a control force dependent on the inlet pressure of the main pump.

[0003] Furthermore, the document DE 103 52 029 A1 discloses a positive displacement pump with a pre-charging device. The positive displacement pump comprises: a housing with an inlet and an outlet for a fluid to be pumped, a displacement chamber contained in the housing, into which the inlet and the outlet open, a displacement element accommodated in the displacement chamber, which performs a conveying movement by which fluid is pumped from the inlet into the outlet, increasing its pressure, a drive shaft, the rotational movement of which causes the conveying movement of the displacement element, and a pre-charging device that pumps the fluid through the inlet. The pre-charging device is a flow pump with at least one conveying wheel rotationally driven by the drive shaft.

[0004] Further fluid conveying devices are known from the documents JP S58 93977 A, JP H04 111586 U, JP S58 93976 A, JP 2015 059566 A, US 3 532 441 A and CN 104 806 468 A.

[0005] The object of the invention is to propose a fluid conveying device which has advantages over known fluid conveying devices, in particular realizing a high conveying capacity with simultaneous high efficiency.

[0006] This is achieved according to the invention with a fluid conveying device having the features of claim 1. It is provided that the backing pump is designed as an at least partially uncompensated internal gear pump and has a higher limiting speed and a larger pump volume than the main pump, and that a suction chamber of the backing pump extends over a larger angular range than a suction chamber of the main pump and / or a pressure chamber of the backing pump extends over at least the same angular range as a pressure chamber of the main pump.

[0007] The fluid conveying device is used to convey a fluid, for example, a liquid or a gas. For this purpose, the fluid conveying device has a backing pump and a main pump, with the main pump being fluidly connected to the backing pump. This means that the fluid is first fed to the backing pump, which conveys the fluid toward the main pump. The fluid conveyed by the backing pump is then made available to the main pump, which conveys the fluid further, for example, toward a fluid outlet of the fluid conveying device, which can also be referred to as the conveying device fluid outlet.

[0008] Each of the pumps has an input shaft via which it is driven, namely the backing pump via the backing pump input shaft and the main pump via the main pump input shaft. The backing pump also has two gears for conveying fluid, namely the backing pump pinion and the backing pump ring gear. The backing pump pinion has external teeth and the backing pump ring gear has internal teeth. The external teeth and the internal teeth mesh with each other in some areas. The backing pump pinion and the backing pump ring gear are intended for conveying fluid and are therefore designed in such a way that when the backing pump input shaft rotates they interact to convey the fluid and, for example, mesh with each other or engage with each other.

[0009] The backing pump pinion is coupled to the backing pump input shaft, preferably rigidly and / or permanently. The backing pump pinion is preferably arranged on the backing pump input shaft so that, during operation of the backing pump, it always has the same speed as the backing pump input shaft. The backing pump input shaft is drive-coupled to the common drive shaft, preferably again rigidly and / or permanently. For example, the backing pump input shaft and the common drive shaft are designed as a single piece, so that the backing pump input shaft is formed by the drive shaft and / or vice versa. In this respect, the backing pump can be driven directly and immediately via the drive shaft.

[0010] Similarly, the main pump has the main pump pinion and the main pump ring gear. The main pump pinion has external teeth, while the main pump ring gear has internal teeth. The external and internal teeth mesh with each other in certain areas. The main pump pinion and the main pump ring gear are, in turn, intended for fluid delivery and are designed such that they interact to deliver the fluid when the main pump input shaft rotates, for example, meshing with each other.

[0011] It can be provided that the main pump input shaft is drive-coupled to the common drive shaft, analogous to the pre-pump input shaft, preferably rigidly and / or permanently. For example, the pump input shaft and the common drive shaft are designed as a single piece, so that the main pump input shaft is formed by the drive shaft and / or vice versa. In this respect, the main pump can be driven directly and immediately via the drive shaft. It is particularly preferably provided that both the pre-pump input shaft and the main pump input shaft are formed by the common drive shaft. In other words, the pre-pump input shaft and the main pump input shaft are designed as a single piece and / or from the same material, so that together they form the drive shaft. Accordingly, the pre-pump input shaft and the main pump input shaft are arranged coaxially to one another.In such a design, the backing pump and the main pump are always operated at the same speed.

[0012] Alternatively, the main pump can be driven only indirectly via the drive shaft. For this purpose, the main pump is connected to the drive shaft via the backing pump, so that upon rotation of the drive shaft, the main pump is driven via the backing pump. Preferably, the backing pump pinion and the backing pump ring gear are connected to each other. This means that the backing pump pinion is provided and configured to drive the backing pump ring gear, so that upon rotation of the backing pump input shaft, a rotational movement of both the backing pump pinion and the backing pump ring gear occurs.

[0013] The backing pump ring gear is now drive-connected to the main pump input shaft, namely via a connecting shaft. In other words, the main pump is drive-connected to the backing pump ring gear, so that a rotational movement of the backing pump ring gear preferably also results in a rotational movement of the main pump input shaft. The main pump input shaft and the connecting shaft can be designed separately or as one piece. In the latter case, the main pump input shaft forms the connecting shaft and / or vice versa. For example, the backing pump ring gear is rotatably mounted by means of the connecting shaft and / or the main pump input shaft.

[0014] This means that in this embodiment, the fluid conveying device is designed such that the backing pump input shaft is directly and immediately coupled to the drive shaft. The main pump input shaft, on the other hand, is only indirectly coupled to the drive shaft via the connecting shaft and / or the backing pump. Such a design of the fluid conveying device has the advantage that the speeds of the backing pump and the main pump, or rather the respective input shaft, are in a fixed relationship with one another, so that, for example, there is a specific ratio between the speeds and the two pumps are operated at different speeds. This achieves very good coordination between the backing pump and the main pump during operation of the fluid conveying device.

[0015] In any case – regardless of the connection of the backing pump and the main pump to the drive shaft – the backing pump is an at least partially uncompensated internal gear pump and the main pump is an at least partially compensated internal gear pump. In this embodiment, both pumps, i.e. both the backing pump and the main pump, are designed as internal gear pumps. The main pump is axially and / or radially compensated. It can be provided that the main pump is axially compensated and radially uncompensated, axially uncompensated and radially compensated, or both axially compensated and radially compensated. Axial compensation means that, viewed in the axial direction with respect to the respective internal gear pump, an axial disk is arranged between the pinion and the ring gear of the internal gear pump.

[0016] The axial disc can be displaced in the axial direction with slight play. During operation of the respective gear pump or internal gear pump, it is forced in the axial direction towards the pinion and the ring gear and preferably rests against them at least temporarily, in particular continuously. Particularly preferably, such an axial disc is present in the axial direction on opposite sides of the pinion and the ring gear. For example, the axial discs are each arranged between the pinion and the ring gear on the one hand and a machine housing of the main pump on the other hand, i.e. on the end face of the pinion and the ring gear. Insofar as only one axial disc is discussed below, the explanations can always be applied to any of the multiple axial discs, where provided.

[0017] The axial disc is preferably mounted in the machine housing in a rotationally fixed manner. On its side facing away from the pinion and the ring gear and thus facing the machine housing, it can have a pressure field, which is designed, for example, in the form of a recess in the axial disc. The pressure field can be subjected to pressurized fluid via a fluid channel formed in the machine housing. For example, the pressure field is fluidly connected to a pressure side of the gear pump or internal gear pump via the fluid channel. During operation of the gear pump or internal gear pump, the pressure field is pressurized via the fluid channel and the axial disc is accordingly forced in the axial direction towards the pinion and the ring gear, in particular against the pinion and the ring gear.

[0018] In addition or alternatively to the axial compensation, radial compensation of the internal gear pump is provided. The internal gear pump has a filler piece which is arranged between the pinion and the ring gear in the radial direction with respect to a rotational axis of the pinion. The filler piece serves to fluidically separate a pressure side from a suction side of the internal gear pump or a pressure chamber from a suction chamber, which are also formed in the radial direction between the pinion and the ring gear. In the case of radial compensation, the filler piece is designed in several parts and has a first filler piece part which rests on the pinion and a second filler piece part which rests on the ring gear.The two filler pieces are radially movable relative to each other and are designed such that the first filler piece is pushed radially inward toward the pinion, and the second filler piece is pushed radially outward toward the ring gear. This ensures excellent sealing of the pressure chamber from the suction chamber throughout the service life of the internal gear pump.

[0019] For example, a pressure chamber located radially between the first filler piece and the second filler piece is fluidically connected to the pressure side of the internal gear pump, such that the pressure chamber is pressurized during operation of the internal gear pump. Due to the pressurization, the two filler pieces are subjected to force in the radial direction, such that the first filler piece is pushed towards or against the pinion and the second filler piece is pushed towards or in the direction of the ring gear. It is therefore preferably provided for the axial compensation and / or the radial compensation of the internal gear pump to take place as a function of a pressure on the pressure side of the internal gear pump. The sealing effect achieved by means of the axial disc and / or the filler piece is therefore greater the greater the pressure on the pressure side of the internal gear pump.

[0020] As already explained above, the main pump can be designed with axial compensation, with radial compensation, or with both axial and radial compensation. The backing pump designed as an internal gear pump, on the other hand, is partially uncompensated, i.e., either axially uncompensated or radially uncompensated. Particularly preferably, it is both axially uncompensated and radially uncompensated. For example, the backing pump does not have the compensation that the main pump has. Therefore, if the main pump is axially compensated and radially uncompensated, the backing pump is axially uncompensated and radially compensated. If, on the other hand, the main pump is axially uncompensated and radially compensated, the backing pump is axially compensated and radially uncompensated. If the main pump is axially compensated and radially compensated, the backing pump is axially uncompensated and radially uncompensated.With such a design of the fluid conveying device, very high speeds of at least the backing pump, but preferably also the main pump, can be achieved, so that the fluid conveying device as a whole is designed for extremely high fluid throughputs.

[0021] A further embodiment of the invention provides that the backing pump has a backing pump pinion and a backing pump ring gear, and the main pump has a main pump pinion and a main pump ring gear, wherein the backing pump pinion and the main pump pinion are arranged coaxially and the backing pump ring gear and the main pump ring gear are arranged axially offset from one another. The embodiments for the main pump are of course also applicable to the backing pump designed as a centrifugal pump. The backing pump pinion is mounted for rotation about a backing pump pinion axis, the backing pump ring gear about a backing pump ring gear axis, the main pump pinion about a main pump pinion axis, and the main pump ring gear about a main pump ring gear axis. The axes of rotation of the pinion and the ring gear of both the backing pump and the main pump are arranged axially offset from one another, so that their axes of rotation are spaced parallel to one another.A preferred embodiment of the fluid conveying device is one in which the backing pump pinion and the main pump pinion are arranged coaxially with each other, so that their axes of rotation coincide or are identical. The backing pump ring gear and the main pump ring gear, however, should be arranged axially offset from each other, so that the backing pump ring gear rotation axis and the main pump ring gear rotation axis are parallel and spaced apart from each other. This enables a particularly advantageous fluid flow between the backing pump and the main pump.

[0022] Alternatively, it can of course also be provided that the pre-pump pinion and the main pump pinion are arranged coaxially to one another, as are the pre-pump ring gear and the main pump ring gear. In this case, the pre-pump pinion rotational axis and the main pump pinion rotational axis coincide. This also applies to the pre-pump ring gear rotational axis and the main pump ring gear rotational axis. In any case, it can be provided that the pre-pump pinion and the main pump pinion have identical dimensions in the radial direction. Particularly preferably, the pre-pump pinion and the main pump pinion are identical in construction or have an identical design. The pre-pump ring gear and the main pump ring gear additionally or alternatively have identical dimensions in the radial direction. Particularly preferably, they are identical in construction or have an identical design.The dimensions of the pinions refer to the dimensions of their outer circumference, and the dimensions of the ring gears refer to the dimensions of their inner circumference. In other words, the dimensions of the pinions and ring gears correspond to the respective tip diameter of the corresponding gearing, i.e., the external teeth of the pinions and the internal teeth of the ring gears.

[0023] Particularly preferably, the teeth of the backing pump pinion and the main pump pinion and / or the teeth of the backing pump ring gear and the main pump ring gear are arranged offset from one another in the circumferential direction, for example, by half a tooth pitch. This can prevent pulsations in the fluid conveying device.

[0024] The invention provides that the backing pump has a higher limiting speed than the main pump, and that the backing pump has a larger pump volume than the main pump. Due to the at least partial or complete lack of compensation of the backing pump, it is suitable for higher limiting speeds than the at least partially compensated main pump. Such a design of the fluid conveying device ensures that the main pump is always optimally supplied with fluid from the backing pump. In addition, the backing pump has the larger pump volume compared to the main pump. The pump volume can also be referred to as the geometric delivery volume. This in turn describes a delivery volume of the respective pump during one rotation of the respective input shaft, i.e. the backing pump input shaft for the backing pump and the main pump input shaft for the main pump.The geometric displacement ignores tolerances, play, and deformations that may occur during operation of the respective pump. The larger pump volume of the booster pump enables consistently reliable fluid supply to the main pump.

[0025] Within the scope of a further embodiment of the invention, it is provided that the backing pump and the main pump are arranged in a common machine housing. This has the advantage of simple, cost-effective production of the fluid conveying device. For example, the machine housing is designed such that the backing pump pinion and the backing pump ring gear are introduced into the machine housing from one side, viewed in the axial direction, and the main pump pinion and the main pump ring gear are introduced into the machine housing from the other side when the fluid conveying device is assembled. To this extent, a partition wall is arranged in the machine housing, which fluidically separates the backing pump and the main pump from one another at least in some areas. In any case, the backing pump and the main pump are preferably arranged adjacent to one another in the axial direction, in particular at a distance from one another, i.e. without overlap, viewed in the axial direction, in the machine housing.

[0026] According to the invention, it is provided that a suction chamber of the backing pump extends over a larger angular range than a suction chamber of the main pump, and / or that a pressure chamber of the backing pump extends over at least the same angular range as a pressure chamber of the main pump. The suction chamber and the pressure chamber are located in the radial direction between the pinion and the ring gear of the respective pump, as seen in cross-section. In other words, the suction chamber and the pressure chamber are each delimited in the radially inward direction by the pinion and in the radially outward direction by the ring gear. The pinion and the ring gear of the respective pump are designed such that they convey fluid located in the suction chamber towards the pressure chamber.

[0027] For example, the fluid is supplied to the suction chamber in the axial direction and / or in the radial direction. For supplying the fluid in the axial direction, for example, at least one inlet channel is formed in the machine housing. For supplying it in the radial direction, the respective ring gear has at least one recess which opens into the suction chamber at least temporarily. The fluid can be withdrawn from the pressure chamber in the axial direction and / or in the radial direction. For withdrawal in the axial direction, an outlet channel is formed in the machine housing. For withdrawal in the radial direction, the ring gear has the recess which is at least temporarily in flow connection with the pressure chamber. Via the recess, a flow connection is thus established, at least temporarily, between the pressure chamber and the outlet channel or an outlet of the fluid conveying device.

[0028] Viewed in cross-section, the suction chamber of the backing pump extends over a larger angular range than the suction chamber of the main pump. This is achieved in particular by a different design of the filler piece, which is smaller in the circumferential direction for the backing pump than for the main pump. The greater extension of the suction chamber of the backing pump enables a high speed of the backing pump because the cavitation tendency of the backing pump is reduced due to the greater distance available for filling the suction chamber with fluid. The larger dimensions of the suction chamber reduce the flow velocity of the fluid required to fill the suction chamber. Particularly preferably, the angular range over which the suction chamber of the backing pump extends is at least 25%, at least 50%, at least 75% or at least 100% greater than the angular range over which the suction chamber of the main pump extends.

[0029] Additionally or alternatively, the pressure chamber of the backing pump is at least as large in cross-section as the pressure chamber of the main pump, thus extending over at least the same angular range. Of course, it can also be provided here that the pressure chamber of the backing pump extends over a larger angular range than the pressure chamber of the main pump. Preferably, the angular range over which the pressure chamber of the backing pump extends is at least 10%, at least 20%, or at least 25% larger than the angular range over which the pressure chamber of the main pump extends. This enables the high speed of the backing pump described above.

[0030] A further embodiment of the invention provides that the suction chamber and the pressure chamber of the backing pump are directly fluidically connected to one another via an overflow valve. The overflow valve is designed such that it establishes a flow connection between the pressure chamber and the suction chamber when a certain pressure difference between the pressure chamber and the suction chamber is exceeded, and interrupts it otherwise. The overflow valve thus serves as a pressure relief valve which opens when a certain pressure difference between the pressure chamber and the suction chamber is reached or exceeded, so that the pressure present in the pressure chamber can be reduced in the direction of the suction chamber. The overflow valve closes as soon as the pressure difference between the pressure chamber and the suction chamber falls below the certain pressure difference again. The overflow valve can be integrated into the machine housing or arranged outside the machine housing.The overflow valve prevents the maximum pressure from being exceeded and / or the occurrence of cavitation in the backing pump, thus ensuring a reliable supply of fluid to the main pump at all times.

[0031] Within the scope of a further embodiment of the invention, it is provided that the angular range over which the suction chamber of the backing pump extends in the circumferential direction is at least 180°, at least 190°, at least 200°, at least 210°, at least 220°, or at least 225°. With such an extension of the suction chamber in the circumferential direction, reliable filling of the suction chamber is achieved even at high speeds of the backing pump.

[0032] A further development of the invention provides that in the backing pump, a backing pump filler piece is arranged between the backing pump pinion and the backing pump ring gear, and in the main pump, a main pump filler piece is arranged between the main pump pinion and the main pump ring gear, wherein the backing pump filler piece has a smaller angular extent in the circumferential direction with respect to a rotational axis of the backing pump pinion than the main pump filler piece in the circumferential direction with respect to a rotational axis of the main pump pinion. As already explained, the respective filler piece serves to fluidically separate the pressure chamber from the suction chamber. For this purpose, the filler piece rests in a sealing manner on the one hand on the respective pinion and on the other hand on the respective ring gear in the radial direction or as seen in cross-section.To achieve the largest possible circumferential extension of the suction chamber for the backing pump, the backing pump filler piece is designed with a smaller angular extension in the circumferential direction than the main pump filler piece. The angular extension of each filler piece refers to the angle relative to the respective pinion rotation axis. The described design of the filler pieces ensures reliable filling of the backing pump's suction chamber at high speeds.

[0033] A preferred further embodiment of the invention provides that the backing pump filler, the backing pump pinion and the backing pump ring gear are arranged and / or designed in such a way that a sealing effect between the backing pump filler and the backing pump pinion and / or a sealing effect between the backing pump filler and the backing pump ring gear is greater on a side of the backing pump filler facing the pressure chamber than on a side of the backing pump filler facing the suction chamber. Viewed in cross-section, the backing pump filler lies in sealing contact on the one hand against the backing pump pinion and on the other hand against the backing pump ring gear. Viewed in the circumferential direction, the sealing effect between the backing pump filler and the backing pump pinion is greater on the side facing the pressure chamber than on the side facing the suction chamber. In particular, the sealing effect decreases in the circumferential direction, starting from the pressure chamber in the direction of the suction chamber, in particular continuously.

[0034] Additionally or alternatively, this applies to the sealing effect between the backing pump filler piece and the backing pump ring gear. The sealing effect is greater the greater the contact pressure of the backing pump filler piece against the backing pump pinion or the backing pump ring gear. This ultimately means that the contact pressure of the backing pump filler piece against the backing pump pinion or the backing pump ring gear is greater on the side of the backing pump filler piece facing the pressure chamber than on the side facing the suction chamber, or that the contact pressure decreases, preferably continuously, starting from the side facing the pressure chamber towards the side facing the suction chamber. This in turn enables a particularly large design of the suction chamber of the backing pump with the advantages already described.

[0035] Within the scope of a further embodiment of the invention, it can be provided that before commissioning, the backing pump pinion is designed with an oversize relative to the backing pump filler piece and / or the backing pump ring gear is designed with an undersize relative to the backing pump filler piece, so that during running-in, running-in wear occurs, by means of which a play-free fit is achieved. In other words, the backing pump pinion or the backing pump ring gear is designed with a press fit relative to the backing pump filler piece, or conversely, the backing pump filler piece is designed with a press fit relative to the backing pump pinion and / or the backing pump ring gear. During commissioning of the fluid conveying device, running-in wear occurs, by means of which the backing pump pinion, the backing pump ring gear and / or the backing pump filler piece are worn away in such a way that the play-free fit is subsequently achieved, which realizes a particularly high sealing effect.Particularly preferably, the backing pump filler piece is made of a softer material than the backing pump pinion and the backing pump ring gear, so that the backing pump filler piece is essentially worn away during running-in. Due to the play-free fit that exists after running-in, a particularly good seal is achieved between the pressure chamber and the suction chamber of the backing pump, which in turn leads to high achievable pressures.

[0036] The invention will be explained in more detail below with reference to the exemplary embodiments shown in the drawings, without limiting the invention. In the drawings: Figure 1 shows a schematic longitudinal section through a fluid conveying device with a backing pump and a main pump, Figure 2 shows a schematic cross-sectional view through the fluid conveying device, Figure 3 shows a schematic cross-sectional view through the fluid conveying device in the region of the backing pump, and Figure 4 shows a schematic longitudinal section through the fluid conveying device in a further embodiment not according to the invention.

[0037] The Figure 1shows a schematic longitudinal sectional view through a fluid conveying device 1, which has a backing pump 2 and a main pump 3 fluidly connected to the backing pump 2. The fluid conveying device 1 has a fluid inlet 4 and a fluid outlet 5 and is designed such that it conveys fluid from the fluid inlet 4 in the direction of the fluid outlet 5. The backing pump 2 is fluidly connected directly to the fluid inlet 4, but only indirectly via the main pump 3 to the fluid outlet 5. Conversely, the main pump 3 is fluidly connected only indirectly via the backing pump 2 to the fluid inlet 4, but directly to the fluid outlet 5. This means that the fluid provided at the fluid inlet 4 is conveyed by the backing pump 2 in the direction of the main pump 3 and is conveyed further by the main pump 3 in the direction of the fluid outlet 5, at which it is subsequently available.

[0038] The backing pump 2 and the main pump 3 are arranged in a common machine housing 6 or pump housing, on which both the fluid inlet 4 and the fluid outlet 5 are formed. A drive shaft 7 is rotatably mounted in the machine housing 6, by means of which a backing pump input shaft 8 and a main pump input shaft 9 can be driven. In the exemplary embodiment shown here, the backing pump input shaft 8 and the main pump input shaft 9 are designed as a single piece and / or from the same material. The drive shaft 7 is preferably rotationally fixedly coupled to the backing pump input shaft 8 and the main pump input shaft 9 via a positive connection, for example a toothed connection. The backing pump 2 has a backing pump pinion 10 and a backing pump ring gear 11 and is designed as an internal gear pump.The pre-pump pinion 10 has an external toothing 12, which meshes partially with an internal toothing 13 of the pre-pump ring gear 11 to convey the fluid. In the exemplary embodiment shown here, the pre-pump pinion 10 is connected to the pre-pump input shaft 8 via a toothing in a rotationally fixed manner, but is displaceable in the axial direction. However, it can also be provided that the pre-pump pinion 10 is formed integrally and / or of the same material as the pre-pump input shaft 8.

[0039] The main pump 3 has a main pump pinion 14 and a main pump ring gear 15. The main pump pinion 14 has external teeth 16 which, viewed in the circumferential direction, only partially mesh with internal teeth 17 of the main pump ring gear 15. In the backing pump 2, a suction chamber 18 is located radially between the backing pump pinion 10 and the backing pump ring gear 11. This also applies to a pressure chamber 19. The suction chamber 18 is directly fluidically connected to the fluid inlet 4, with the backing pump 2 being designed such that the fluid can flow into the suction chamber 18 from both sides in the axial direction. Accordingly, there is a flow connection from the fluid inlet 4 to both sides of the suction chamber 18.The pressure chamber 19 is fluidically connected to the main pump 3 via a flow channel 20 formed in the machine housing 6, namely to a suction chamber 21 of the main pump, which is located in the radial direction between the main pump pinion 14 and the main pump ring gear 15.

[0040] The main pump 3 is designed such that the flow channel 20 is fluidically connected to the suction chamber 21 on both sides, viewed in the axial direction, so that fluid can flow from the flow channel 20 into the suction chamber 21 of the main pump 3 on both sides, viewed in the axial direction. In addition, recesses 22 are formed in the main pump ring gear 15, via which an additional flow connection exists between the flow channel 20 and the suction chamber 21. The main pump 3 further has a pressure chamber 23, which is located in the radial direction between the main pump pinion and the main pump ring gear 15. The pressure chamber 23 is in flow connection with the fluid outlet 5 via the recesses 22, preferably exclusively. This means that fluid present in the pressure chamber 23 can escape from the pressure chamber 23 in the direction of the fluid outlet 5 exclusively via at least one of the recesses 22.

[0041] In the exemplary embodiment shown here, the main pump 3 is at least axially compensated, i.e., it has an axial compensation 24. For this purpose, an axial disk 25 is arranged on both sides of the main pump pinion 14 and the main pump ring gear 15, as seen in the axial direction. During operation of the main pump 3, these axial disks are urged in the direction of the main pump pinion 14 and the main pump ring gear 15 and lie sealingly against the end faces of the main pump pinion 14 and the main pump ring gear 15. For this purpose, the axial disks 25 are pressurized from the pressure chamber 23 of the main pump 3. For example, an opening 26 is formed in the axial disks 25 for this purpose, via which opening the pressure chamber 23 is in flow connection with a pressure field 27, which is present on the side of the axial disk facing away from the pressure chamber 23.

[0042] The Figure 2shows a schematic cross-sectional view of the fluid conveying device 1, wherein the pre-pump pinion 10, the pre-pump ring gear 11, the main pump pinion 14, and the main pump ring gear 15 are shown. The pre-pump pinion 10 is rotatably mounted about a pre-pump pinion rotation axis 28, the pre-pump ring gear 11 about a pre-pump ring gear rotation axis 29, the main pump pinion 14 about a main pump pinion rotation axis 30, and the main pump ring gear 15 about a main pump ring gear rotation axis 31. It can be seen that the pre-pump pinion rotation axis 28 and the main pump pinion rotation axis 30 are identical, so that the pre-pump pinion 10 and the main pump pinion 14 are arranged coaxially to one another. The pre-pump ring gear rotation axis 29 is arranged parallel and spaced from the pre-pump pinion rotation axis 28 and the main pump ring gear rotation axis 31 is arranged parallel and spaced from the main pump pinion rotation axis 30.

[0043] In the embodiment of the fluid conveying device 1 shown here, the main pump ring gear rotation axis 31 and the backing pump ring gear rotation axis 29 are arranged on opposite sides of the backing pump pinion rotation axis 28. In other words, the backing pump pinion rotation axis 28, the backing pump ring gear rotation axis 29, the main pump pinion rotation axis 30, and the main pump ring gear rotation axis 31 lie on an imaginary straight line, wherein the backing pump ring gear rotation axis 29 and the main pump ring gear rotation axis 31 are arranged on opposite sides of the backing pump pinion rotation axis 28 and particularly preferably have the same distance a from it. As shown here, it can be provided that the teeth of the backing pump pinion 10 and the teeth of the main pump pinion 14 are arranged offset from one another in the circumferential direction, i.e., as viewed in the axial direction, they do not overlap or are not aligned with one another. This can effectively prevent the occurrence of pulsations.For example, an offset of half a tooth pitch is provided, so that each tooth of the pre-pump pinion 10 is centered between two teeth of the main pump pinion 14, or vice versa. However, any other offset in the circumferential direction can also be selected.

[0044] The Figure 3shows a schematic cross-sectional view of the fluid conveying device 1 in the area of ​​the backing pump 2. The backing pump input shaft 8, the backing pump pinion 10 and the backing pump ring gear 11, which are arranged in the machine housing 6, can be seen. A backing pump filler piece 32, which is shown here in two different positions, is arranged between the backing pump pinion 10 and the backing pump ring gear 11 to fluidically separate the suction chamber 18 from the pressure chamber 19. It can be seen that the backing pump filler piece 32 has a comparatively small extension or angular extension in the circumferential direction. Accordingly, the angular range α, over which the suction chamber 18 extends in the circumferential direction, is very large for both arrangements of the backing pump filler piece 32 and is at least 150°, preferably at least 180° or more than 180°. This ensures particularly rapid filling of the suction chamber 18 with fluid.

[0045] It is clear from the described figures that the backing pump 2 is designed to be uncompensated and, in the exemplary embodiment shown here, has neither axial compensation nor radial compensation. The main pump, on the other hand, is designed to be compensated and, in the exemplary embodiment shown here, has at least the axial compensation 24. Additionally or alternatively, the main pump 3 can be designed with radial compensation. The described design of the fluid delivery device 1 enables a particularly high speed, in particular of the backing pump 2. This ensures a reliable supply of fluid to the main pump 3, so that overall the fluid delivery device 1 realizes a high delivery pressure or a high pressure ratio between the pressure at the fluid outlet 5 and the pressure at the fluid inlet 4.

[0046] The Figure 4shows a schematic longitudinal sectional view of the fluid conveying device 1 in a further embodiment not according to the invention. This corresponds in essential parts to the fluid conveying device 1 described so far, so that reference is made to the corresponding embodiments, and only the differences will be discussed below. These lie in the fact that the backing pump 2 is not designed as an internal gear pump, but as a centrifugal pump. The backing pump 2, designed as a centrifugal pump, has an impeller 33, which in the embodiment shown here is a radial pump impeller. Accordingly, the centrifugal pump is designed as a radial pump. The impeller 33 has a diameter D 1 , which in the embodiment shown here corresponds to an outer diameter D 2 of the main pump ring gear 15. In any case, however, the diameter D 1 of the impeller 33 corresponds to a maximum of 125% of the outer diameter D 2 of the main pump ring gear 15.It can be seen that the impeller 33 of the backing pump 2 is again arranged coaxially with the main pump pinion 14. This results in a particularly compact design of the fluid conveying device 1.

[0047] Separating the suction chamber 18 from the pressure chamber 19, a backing pump filler 32 is arranged, which is shown here in two different positions. It can be seen that the backing pump filler 32 has a comparatively small extension or angular extension in the circumferential direction. Accordingly, the angular range α over which the suction chamber 18 extends in the circumferential direction is very large for both arrangements of the backing pump filler 32 and amounts to at least 150°, preferably at least 180° or more than 180°. This ensures particularly rapid filling of the suction chamber 18 with fluid.

[0048] It is clear from the described figures that the backing pump 2 is designed to be uncompensated and, in the exemplary embodiment shown here, has neither axial compensation nor radial compensation. The main pump, on the other hand, is designed to be compensated and, in the exemplary embodiment shown here, has at least the axial compensation 24. Additionally or alternatively, the main pump 3 can be designed with radial compensation. The described design of the fluid delivery device 1 enables a particularly high speed, in particular of the backing pump 2. This ensures a reliable supply of fluid to the main pump 3, so that overall the fluid delivery device 1 realizes a high delivery pressure or a high pressure ratio between the pressure at the fluid outlet 5 and the pressure at the fluid inlet 4.

[0049] The Figure 4shows a schematic longitudinal sectional view of the fluid conveying device 1 in a further embodiment. This essentially corresponds to the previously described fluid conveying device 1, so that reference is made to the corresponding embodiments, and only the differences will be discussed below. These lie in the fact that the backing pump 2 is not designed as an internal gear pump, but as a centrifugal pump. The backing pump 2, designed as a centrifugal pump, has an impeller 33, which in the embodiment shown here is a radial pump impeller. Accordingly, the centrifugal pump is designed as a radial pump. The impeller 33 has a diameter D 1 , which in the embodiment shown here corresponds to an outer diameter D 2 of the main pump ring gear 15. In any case, however, the diameter D 1 of the impeller 33 corresponds to a maximum of 125% of the outer diameter D 2 of the main pump ring gear 15.It can be seen that the impeller 33 of the backing pump 2 is again arranged coaxially with the main pump pinion 14. This results in a particularly compact design of the fluid conveying device 1.

Claims

1. Fluid delivery device (1) having a primary pump (2) and a main pump (3) fluidically connected to the primary pump (2), wherein the primary pump (2) is drivable by a primary pump input shaft (8) and the main pump (3) is drivable by a main pump input shaft (9) and the primary pump input shaft (8) and the main pump input shaft (9) are mechanically coupled to a common drive shaft (7) of the fluid delivery device (1), wherein the main pump (3) is designed as an at least partially compensated internal gear pump, characterized in that the primary pump (2) is designed as an at least partially non-compensated internal gear pump and has a higher limit speed and a larger pump volume than the main pump (3), and that a suction chamber (18) of the primary pump (2) extends over a larger angular range (α) than a suction chamber (21) of the main pump (3) and / or a pressure chamber (19) of the primary pump (2) extends over at least the same angular range as a pressure chamber (23) of the main pump (3).

2. Fluid delivery device according to claim 1, characterized in that the primary pump (2) comprises a primary pump sprocket (10) and a primary pump hollow wheel (11), and the main pump (3) comprises a main pump sprocket (14) and a main pump hollow wheel (15), wherein the primary pump sprocket (10) and the main pump sprocket (14) are arranged coaxially and the primary pump hollow wheel (11) and the main pump hollow wheel (15) are arranged to be radially offset from one another.

3. Fluid delivery device according to any one of the preceding claims, characterized in that the primary pump (2) and the main pump (3) are arranged in a common machine housing.

4. Fluid delivery device according to any one of the preceding claims, characterized in that the suction chamber (18) and the pressure chamber (19) of the primary pump (2) are directly fluidically connected to one another via an overflow valve.

5. Fluid delivery device according to any one of the preceding claims, characterized in that the angular range (α) over which the suction chamber (18) of the primary pump (2) extends in a circumferential direction, is at least 180°, at least 190°, at least 200°, at least 210°, at least 220° or at least 225°.

6. Fluid delivery device according to any one of the preceding claims, characterized in that a primary pump filler piece (32) is arranged in the primary pump (2) between the primary pump sprocket (10) and the primary pump hollow wheel (11), and a main pump filler piece is arranged in the main pump (3) between the main pump filler piece (14) and the main pump hollow wheel (15), wherein the primary pump filler piece (32) has a smaller angular extension in a circumferential direction with respect to a rotational axis of the primary pump sprocket (10) than the main pump filler piece in the circumferential direction with respect to a rotational axis of the main pump sprocket (14).

7. Fluid delivery device according to any one of the preceding claims, characterized in that the primary pump filler piece (32), the primary pump sprocket (10), and the primary pump hollow wheel (11) are arranged and / or configured in such a way that a sealing effect between the primary pump filler piece (32) and the primary pump sprocket (10) and / or a sealing effect between the primary pump filler piece (32) and the primary pump hollow wheel (11) on a side of the primary pump filler piece (32) facing the pressure chamber (18) is larger than on a side of the primary pump filler piece (32) facing the suction chamber (18).

8. Fluid delivery device according to any one of the preceding claims, characterized in that prior to start-up, the primary pump sprocket (10) is designed to be oversized with respect to the primary pump filler piece (32) and / or the primary pump hollow wheel (11) is designed to be undersized with respect to the primary pump filler piece (32), so that a running-in wear occurs during running-in, resulting in a clearance fit.