Pump and motor vehicle with such a pump

Abstract

Pump (1) with a pump stage (3) and an electric motor (2) by which the pump stage (3) can be driven, - wherein the pump stage (3) is designed as a spindle pump stage (3) with at least two spindles (4a, 4b) and comprises a pump stage housing (5), - wherein the pump stage housing (5) has a spindle receptacle (6a, 6b) for each spindle (4a, 4b) which extends from a suction area (7) to a pressure area (8) of the pump stage housing (5), - wherein each of the spindles (4a, 4b) is arranged in one of the spindle mounts (6a, 6b), - wherein at least one recess (9a, 9b, 9a', 9b') is formed in at least one of the two end regions of at least one of the spindle receptacles (6a, 6b), wherein a transition (10) from the conveying chamber (12) to the recess (9a, 9b, 9a', 9b') runs essentially along the slope of the spindle (4a, 4b) in the respective end region of the spindle receptacle (6a, 6b), characterized in that the recess (9a, 9b, 9a', 9b') is arranged on the suction and pressure side.

Description

Technical field

[0001] The invention relates to a pump with a pump stage and an electric motor by which the pump stage can be driven, wherein the pump stage is designed as a spindle pump stage with at least two spindles and includes a pump stage housing, wherein the pump stage housing has a spindle receptacle for each spindle, which extends from a suction area to a pressure area of ​​the pump stage housing, wherein one of the spindles is arranged in one of the spindle receptacles.

[0002] Furthermore, the invention relates to a motor vehicle with such a pump. State of the art

[0003] The spindles of spindle pumps are largely hydrodynamically supported within the spindle housings in which they are mounted. This hydrodynamic support is achieved through a leakage flow of the pumped fluid, which arises during pumping due to a pressure differential between the pressure chamber (pump chamber) and the suction chamber (suction chamber), and a drag flow resulting from the relative movement of the spindles relative to the spindle housings. However, at the ends of the spindle housings, the pressure is either that of the suction chamber or the pressure chamber. Consequently, no leakage flow occurs at these ends to contribute to the hydrodynamic support of the spindles within the spindle housings during pumping. This results in increased friction and wear between the spindle and the spindle housing in these areas.At the same time, the friction of the spindles in the end area of ​​the spindle mounts negatively affects the efficiency of the feed pump.

[0004] German patent application DE 10 2017 210 767 A1 discloses a fuel pump designed as a spindle pump with two spindles, each spindle being arranged in a spindle receptacle. The spindle receptacles extend cylindrically with a constant cross-section from a suction area to a pressure area of ​​the spindle pump.

[0005] Documents DE 10 2015 101 443 B3, US 2020 / 0 116 148 A1, DE 19 62 464 A, US 2013 / 0 022 458 A1 and EP 2 336 590 A2 disclose spindle pumps. Description of the invention, problem, solution, advantages

[0006] The object of the present invention is to provide a pump that is characterized by less wear and higher efficiency compared to known spindle pumps from the prior art. Furthermore, the pump according to the invention is characterized by a simple design and low cost. A further object is to provide a motor vehicle with such a pump.

[0007] The first task is solved by providing at least one recess in at least one of the two end areas of at least one of the spindle mounts.

[0008] This reduces the frictional contact between the spindle and the spindle housing in which the spindle is located, in the area of ​​the at least one recess. This not only results in less wear on the spindle and the spindle housing in the end region of the spindle housing, but also in an increase in the efficiency of the feed pump, since the recess significantly reduces friction in the end region of the spindle housing where the recess is located.

[0009] Each spindle mount preferably has two end regions, the first of which faces the pressure region and merges into it. The second end region faces the suction region and merges into it. In other words, the end regions are directly adjacent to the suction or pressure region.

[0010] It is particularly advantageous if the recess is located in a region of the end of a spindle mount toward which a resulting force vector from the spindle, especially the directional component of the force vector that lies in a plane transverse to the axis of rotation of the spindle, is directed. This force vector is generated, for example, by an imbalance of the spindle, the interaction of both spindles, and the pressures in the conveying chambers. Since these influences are dynamic, the magnitude and, above all, the direction of the force vector can vary during operation. Therefore, it is particularly preferred if the recess extends over an angular range in the circumferential direction of the spindles that corresponds to the possible force vectors or the respective directional components of the possible force vectors during operation.

[0011] It is particularly preferred if the recess extends at least partially in the circumferential direction of the spindle, which is arranged in the spindle holder. The circumferential direction of the spindle refers to a direction of rotation around the spindle's axis of rotation. Preferably, the recess extends at least 180° around the axis of rotation. It is particularly preferred if the recess extends at least 270° around the axis of rotation. The longer the recess extends in the direction of rotation around the spindle's axis of rotation, the greater its wear-reducing and efficiency-enhancing effect. Therefore, it is especially preferred if the recess extends at least 320° around the axis of rotation.

[0012] Preferably, one of the spindles is a drive spindle that can drive at least the second spindle. This eliminates the need for synchronization and transmission of the rotary motion between the two spindles using gears, although this is also possible.

[0013] The fluid to be pumped is preferably oil, coolant, or fuel. This means that the pump and its components are preferably resistant to oil, coolant, or fuel.

[0014] Furthermore, it is preferred if the pump is designed such that, during the pumping of a liquid to be pumped, the spindles interlock and interact with the spindle mounts in such a way that at least one pumping chamber is formed through which the liquid to be pumped can be pumped from the suction area to the pressure area.

[0015] Additionally, it is preferred if the pump is designed such that a leakage flow develops during pumping due to pressure differences between the pressure area, the at least one pumping chamber, and the suction area. Furthermore, it is preferred if this leakage flow flows between the spindles and the spindle mounts from the pressure area to at least one pumping chamber, and from the at least one pumping chamber to the suction area, thereby forming or at least contributing to a hydrodynamic bearing of the spindles in the spindle mounts.

[0016] It is particularly preferred if the spindle receptacles merge seamlessly along their length. In other words, the adjacent spindle receptacles are fluidically connected along their length via a connecting opening that extends along the longitudinal axis of the spindle receptacles. Specifically, the spindle receptacles have at least a partially circular cross-section in a plane transverse to their direction of extension, i.e., transverse to their longitudinal axis, resulting in essentially cylindrical spindle receptacles. The connecting opening is designed such that the drive spindle engages with the at least second spindle along the spindle receptacles. In other words, the two spindles, each of which has a spindle thread, are drive-connected to each other by means of their spindle threads.

[0017] It is particularly preferred if the recess extends along the spindle receptacle, in a plane perpendicular to the direction of extension of the spindle receptacle, circumferentially from one end of the connecting opening to the other end of the connecting opening. In other words, the recess extends in a plane perpendicular to the axis of rotation of the spindle in the spindle receptacle from one end of the connecting opening to the other end of the connecting opening.

[0018] It is advantageous if the recess is produced by primary forming. It is particularly advantageous if the recess is produced by a casting process. This avoids the need for complex subsequent machining of the spindle mount by grinding, drilling, or milling to form the recess, although these manufacturing processes are also possible in principle. In a further advantageous embodiment of the invention, such machining processes as grinding, drilling, or milling are used to form the recess when producing such a recess by primary forming is not possible or disproportionately complex due to the component or recess geometry. This significantly simplifies manufacturing in such cases.

[0019] It is particularly advantageous if the recess has a continuous profile, as this prevents pressure losses. In other words, a recess is preferred that has no cross-sectional changes, i.e., steps, in any plane along the direction of extension of the spindle mount.

[0020] It is particularly advantageous if the recess forms a concave or convex shape in a plane along the extension direction of the spindle mounts.

[0021] Furthermore, it is advantageous if the recess of the spindle mount has a changing cross-sectional shape and / or cross-sectional area in or against the direction of rotation of the spindle. It is particularly advantageous if the recess of the spindle mount has an increasing cross-sectional area in or against the direction of rotation of the spindle.

[0022] Another preferred embodiment of the invention is characterized in that the recess is arranged on both the suction and pressure sides. It is particularly preferred if one recess is arranged on the suction side and another on the pressure side. This further improves wear reduction and efficiency. In other words, it is possible to provide the recess at the end region of the spindle mount that faces or transitions into the suction area, i.e., borders the suction area. It is also possible, and preferably, to additionally provide the recess at the other end region of the spindle mount that faces or transitions into the pressure area, i.e., borders the pressure area.

[0023] Another preferred embodiment of the invention is characterized in that the recess is formed on both spindle mounts. This further increases wear reduction and efficiency. These effects are particularly advantageous when such a recess is formed on both the pressure and suction sides of each spindle mount.

[0024] Another preferred embodiment of the invention is characterized in that the recess is dimensioned such that, during conveying, the spindle receptacle, which has the recess, is not mechanically contactable in the area of ​​the recess by the spindle arranged in the spindle receptacle. This prevents frictional contact, i.e., grinding, of the spindle against the spindle receptacle, thereby further reducing wear and further increasing the efficiency of the conveying pump.

[0025] Another preferred embodiment of the invention is characterized in that the recess is designed such that it is located only in a region of the spindle receptacle where no leakage current occurs during conveying and thus does not impair the hydrodynamic bearing. In particular, the recess is designed such that it is located only in a region of the spindle receptacle where no leakage current would occur during conveying if no recess were present.

[0026] This ensures that the recess does not extend into an area of ​​the spindle receptacle that, together with the spindles, could form a pumping chamber for conveying the fluid. In other words, it ensures that the pumping capacity of the feed pump is not reduced. It is particularly preferred if the recess extends over at least 60%, at least 80%, at least 90%, or completely over an area of ​​the spindle receptacles in which no leakage flow occurs during pumping that could contribute to the hydrodynamic support of the spindle in the spindle receptacle.

[0027] Another preferred embodiment is characterized in that the recess is located only in a region of the spindle receptacle that cannot be used to form a conveying chamber. It is particularly preferred if the recess extends over at least 60%, at least 80%, at least 90%, or completely over a region of the spindle receptacle that cannot be used to form a conveying chamber. In particular, a conveying chamber is formed and delimited by the spindles and their spindle receptacles.

[0028] Another preferred embodiment is characterized in that the recess is designed such that it is located only in a region of the spindle receptacle where the pressure of the pressure region or the suction region prevails during conveying. In other words, if a suction-side recess is provided, the suction-side recess is arranged in a suction-side region of the spindle receptacles where the pressure of the suction region prevails during conveying, when the spindles are in a position relative to each other in which they, together with the spindle receptacles, form a conveying chamber that adjoins or borders the suction region.Regardless of the above, if a pressure-side recess is provided, the pressure-side recess is arranged in a pressure-side area of ​​the spindle receptacles where, during conveying, the pressure of the pressure zone prevails when the spindles are in a position relative to each other in which they, together with the spindle receptacles, form a conveying chamber that adjoins or borders the pressure zone. It is particularly preferred if the recess extends over at least 50%, 80%, or 90% of this area.

[0029] Another preferred embodiment of the invention is characterized in that the recess extends from the pressure area to the nearest conveying chamber. In other words, the recess extends to the position of one or the nearest conveying chamber. Preferably, the spindles are arranged relative to each other in such a way that they, together with their spindle mounts, form a conveying chamber that adjoins, in particular directly, the pressure area. In other words, the spindles are arranged relative to each other in such a way that they, together with their spindle mounts, form a conveying chamber that is located directly adjacent to the pressure area. The position of the conveying chamber or chambers between the suction area and the pressure area can be changed due to the relative position of the spindles.In other words, the conveying chamber moves from the suction area to the pressure area during operation of the conveying pump, i.e., during the rotation of the spindles. It is particularly advantageous if the recess extends partially or completely from the pressure area to the nearest conveying chamber.

[0030] A preferred embodiment of the invention is characterized in that the recess extends from the suction area to the nearest conveying chamber. In other words, the recess extends from the suction area to the position of one or the nearest conveying chamber. Preferably, the spindles are arranged relative to each other in such a way that, together with their spindle mounts, they form a conveying chamber that adjoins, in particular directly, the suction area. In other words, the spindles are arranged relative to each other in such a way that, together with their spindle mounts, they form a conveying chamber that is located directly adjacent to the suction area. The position of the conveying chamber or chambers between the suction area and the pressure area can be changed due to the relative position of the spindles.In other words, the conveying chamber moves from the suction area to the pressure area during operation of the conveying pump, i.e., during the rotation of the spindles. It is particularly advantageous if the recess extends partially or completely from the pressure area to the nearest conveying chamber.

[0031] Furthermore, it is preferred that during operation, a conveying chamber is formed by the spindles and spindle mounts, which is open in the direction of the pressure area. In other words, such a conveying chamber is limited in the direction of the suction area only by the spindles and spindle mounts, while there is no limitation in the direction of the pressure area.

[0032] In particular, the boundary of a conveying chamber or several conveying chambers is generally formed by the threads of the spindles, i.e. the profiles of the spindles, and the spindle mounts.

[0033] The transition from the conveying chamber to the recess runs essentially along the pitch of the spindle at the respective end of the spindle receptacle. In other words, the recess extends to a transition to the conveying chamber. It is particularly preferred if the transition runs along the pitch of the spindle for at least 50%, 80%, or 90% of its length. This design maximizes the friction reduction provided by the recess without the recess extending into a region where a conveying chamber could be formed between the spindles and their receptacles. In other words, this maximizes friction reduction without compromising pumping performance.

[0034] It is particularly preferred if the transition runs substantially along the spindle thread in the respective end region of the spindle receptacle, in a position of the spindle in which it, together with the further spindle and the spindle receptacles, forms a conveying chamber that adjoins or borders the suction or pressure region. It is highly preferred if the transition extends along the spindle thread for at least 50%, 80%, or 90% of its length.

[0035] In general, a conveying chamber is understood to be a region bounded by at least two spindles and their spindle mounts, in which a pressure difference develops compared to the suction and / or pressure region during the conveying of the fluid. Furthermore, such a conveying chamber serves to convey the fluid from the suction region to the pressure region. Preferably, the pressure difference is large enough to create a leakage flow that contributes to the hydrodynamic support of the spindles in their mounts. The conveying chamber can be moved from the suction region to the pressure region by the rotation of the spindles. The further the conveying chamber moves from the suction region, the greater the pressure difference between the suction region and the conveying chamber becomes. As the conveying chamber approaches the pressure region, the pressure difference between the conveying chamber and the pressure region decreases.If a pumping chamber is located directly adjacent to the pressure or suction area, there is no or barely perceptible pressure difference between the pumping chamber and the respective area. Only with increasing distance from the respective areas does a noticeable pressure difference develop between the pumping chamber and the respective area.

[0036] Pressure generally refers to the pressure of the fluid being pumped.

[0037] A preferred embodiment of the invention is characterized in that the spindles are radially supported only in the spindle receptacles. In other words, no radial support is provided outside the spindle receptacles. A drive-transmitting coupling between the electric motor shaft and the driven spindle by means of a coupling that allows for a longitudinal and / or angular offset between the electric motor shaft is conceivable. In particular, axial support of the spindle or spindles is provided only outside the spindle receptacles. In this way, flow restriction caused by the arrangement of a bearing within the flow is avoided.

[0038] A preferred embodiment of the invention is characterized in that the feed pump is designed as a fuel pump. In this way, an extremely low-wear fuel pump with high efficiency is provided. The fuel pump is particularly preferably a low-pressure fuel pump, which is especially intended to be operated within a fuel tank.

[0039] A preferred embodiment of the invention is characterized in that the feed pump is designed as an oil pump. This provides an extremely low-wear oil pump with high efficiency.

[0040] A preferred embodiment of the invention is characterized in that the feed pump is designed as a coolant pump. This provides an extremely low-wear coolant pump with high efficiency. Such a coolant pump can be used to supply coolant to internal combustion engines. It is also possible to use such a coolant pump to cool electric motors or batteries.

[0041] The problem with regard to the motor vehicle is solved by providing a motor vehicle with at least one fuel pump according to the invention. It is particularly preferred if a motor vehicle has a fuel pump according to the invention designed as a fuel pump, a fuel pump according to the invention designed as an oil pump, and / or a fuel pump according to the invention designed as a coolant pump. In this way, the energy consumption required to drive the two fuel pumps can be reduced, thus providing a fuel-efficient motor vehicle.

[0042] Advantageous embodiments of the present invention are described in the dependent claims and in the following description of the figures. Brief description of the drawings

[0043] The invention will now be explained in detail using exemplary embodiments and with reference to the drawings. The drawings show: Fig. 1 a pump according to the invention, Fig. 2 a pump stage of the inventive feed pump made of Fig. 1, and Fig. 3 a sectional view of the pump stage Fig. 2. Preferred embodiment of the invention

[0044] The Fig. Figure 1 shows a pump 1 according to the invention, comprising an electric motor 2 and a pump stage 3, which is designed as a spindle pump stage. The electric motor 2 directly drives a first spindle 4a via an electric motor shaft 13, wherein the first spindle 4a, driven directly by the electric motor shaft 13, directly drives a second spindle 4b. The spindles 4a and 4b are housed in a multi-part pump stage housing 5 of the pump stage 3.

[0045] The Fig. Figure 2 shows a detailed view of pump stage 3. Pump stage 3 comprises the two spindles 4a and 4b, whereby the first spindle 4a can be driven by the electric motor shaft 13 of the electric motor, and the second spindle 4b can be driven by the first spindle 4a, since the threads of the two spindles 4a and 4b interlock and are thus drive-connected. The spindles 4a and 4b are each located in a spindle receptacle 6a and 6b, meaning that there is one spindle receptacle 6a and 6b for each spindle 4a and 4b. The spindle mounts 6a, 6b extend from a suction area 7 to a pressure area 8 of the pump stage 3. Recesses 9a, 9b, 9a', 9b' are formed at both the ends of the spindle mounts 6a, 6b facing the suction area 7 and at the ends of the spindle mounts 6a, 6b facing the pressure area 8.The recesses 9a', 9b', which are formed at the end region of the spindle receptacles 6 on the pressure area 8, extend to a transition 10 to the conveying chamber 12. The conveying chamber 12 adjoins the pressure area 8 and is bounded by the spindles 4a, 4b and the associated spindle receptacles 6a, 6b. In other words, the spindles 4a, 4b are located in . Fig. 2 in a position relative to each other in which they, together with their spindle receptacles 6a, 6b, form a conveying chamber 12 which adjoins the pressure area 8, i.e., that the conveying chamber 12 borders the pressure area 8. The transition 10, to which the pressure-side recesses 9a', 9b' extend, runs along the thread of the respective spindle 4a, 4b. Furthermore, in Fig. 2 the section path AA is shown.

[0046] The Fig. 3 indicates the pump stage Fig. 2. This is a sectional view corresponding to the section line AA from Fig. 2. For the sake of clarity, a representation of the spindles has been omitted. The illustration shows that the two spindle mounts 6a, 6b are connected to each other by means of a connecting opening 11, which extends over the entire length of the spindle mounts 6a, 6b, i.e., along their longitudinal axis. This means that the spindle mounts 6a, 6b are fluidically connected to each other over their entire length by means of the connecting opening 11, such that the spindles held in the spindle mounts 6a, 6b interlock and are drive-connected. Furthermore, the illustration shows... Fig. 3, that the pressure-side recesses 9a', 9b' in the respective end regions of the spindle receptacles 6a, 6b extend in the plane shown, i.e., in a plane perpendicular to the axis of rotation of a spindle or perpendicular to the longitudinal axis of a spindle receptacle 6a, 6b, from one end of the connecting opening 11 to the other end of the connecting opening in the circumferential direction of the respective spindle receptacle 6 by an angle α or β. Since the pressure-side recesses 9a', 9b', as in Fig. 2 shown and explained, extending to a transition to the conveying chamber and this transition extending along the thread of the spindle, the recesses 9a', 9b' are formed with increasing dimensions along the circumferential direction of the spindle receptacles 6a, 6b.

[0047] The examples of implementation of Fig. Paragraphs 1 to 3, in particular, do not have a limiting character and serve to clarify the inventive idea.

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