Rotary pump with an adjusting device

Abstract

Rotary pump with adjustable delivery volume, the rotary pump comprising a pump housing with a low-pressure inlet and a high-pressure outlet for a fluid to be pumped, a delivery rotor rotatably arranged in the pump housing about an axis of rotation with several conveying means distributed around the circumference of the delivery rotor for conveying the fluid from the low-pressure inlet to the high-pressure outlet, and an actuating element movable translationally back and forth with respect to the pump housing for adjusting the delivery volume of the rotary pump, the actuating element having on the inlet side a first circumferential section which extends circumferentially in the direction of rotation of the delivery rotor and whose axial width is smaller than the axial width of the conveying means, and a second circumferential section which adjoins the first circumferential section in the direction of rotation of the delivery rotor and whose axial width is larger than the axial width of the first circumferential section,wherein a transition from the first circumferential section to the second circumferential section is arranged in each position of the actuating element in the low-pressure inlet.

Description

[0001] The invention relates to a rotary pump with adjustable displacement. The rotary pump comprises a pump housing with a low-pressure inlet and a high-pressure outlet. A delivery rotor rotatable about a rotational axis is arranged within the pump housing. The delivery rotor has a plurality of conveying means for conveying a fluid to be conveyed from the low-pressure inlet to the high-pressure outlet. The conveying means distributed over the circumference of the delivery rotor can be radially movable, in particular with respect to the rotational axis of the delivery rotor. To adjust the delivery volume of the rotary pump, a translationally movable actuating element is arranged in the pump housing. The actuating element preferably limits the radially outward movement of the conveying means with an inner circumferential surface.

[0002] Rotary pumps with adjustable delivery volume are known from the prior art, in which the adjusting element for adjusting the delivery volume is arranged in the pump housing so that it can rotate and / or pivot with respect to the axis of rotation of the delivery rotor. The adjusting element, with its inner circumferential surface, delimits a delivery area of ​​the rotary pump radially outward. The adjusting elements of these known rotary pumps necessarily have circumferential sections that are arranged in the low-pressure inlet regardless of the position of the adjusting element. There is always a circumferential section of the adjusting element that is arranged radially between the delivery rotor, in particular the delivery area, and the fluid flowing in via the low-pressure inlet. In order to nevertheless ensure a radial inflow or supply of fluid to the delivery area, said circumferential sections usually have an axial width that is smaller than the axial width of the conveying means.

[0003] State-of-the-art rotary pumps have the disadvantage that the radial inflow decreases in the direction of rotation of the conveying rotor. This is due to the fact that fluid flowing into the conveying area is entrained and accelerated in the circumferential direction, so that it is subjected to a centrifugal force that increases in the direction of rotation of the conveying rotor and is forced radially outward. This effect negatively impacts the conveying behavior. It can even lead to a portion of the fluid flowing back radially outward into the low-pressure inlet. This undesirable effect depends primarily on the rotational speed of the conveying rotor and occurs in all positions of the control element, being particularly disruptive in positions of maximum discharge volume.

[0004] EP3279477A1 discloses a vane pump with an adjustable displacement volume, wherein an adjusting element is pivotally movable back and forth. The adjusting element has a first circumferential section along its circumference and a second circumferential section adjoining it in the direction of rotation of the conveyor rotor. The transition from the first circumferential section to the second circumferential section is arranged in each position of the adjusting element in the low-pressure inlet.

[0005] It is an object of the invention to provide a rotary pump which has improved pumping performance and is cost-effective to manufacture.

[0006] This problem is solved by the features of claim 1. Advantageous further developments emerge from the dependent claims, the description and the figures.

[0007] The rotary pump according to the invention comprises a pump housing with a low-pressure inlet and a high-pressure outlet for a fluid to be pumped. A delivery rotor rotatable about a rotational axis is arranged within the pump housing. The delivery rotor has a plurality of delivery means distributed over the circumference of the delivery rotor, which can be moved, for example, radially or with a radial directional component with respect to the rotational axis of the delivery rotor. The delivery means can be arranged on a rotor base body of the delivery rotor. To adjust the delivery volume of the rotary pump, the rotary pump comprises an actuating element that can be moved back and forth in translation relative to the pump housing.

[0008] A "translational movement" is understood to mean a change in the position of the corresponding component in relation to the pump housing, in which all components of the component experience the same displacement, i.e. have the same velocity and / or acceleration vector at a given time.

[0009] A "rotary movement" or "rotary movement" is understood to mean a change in the position of the corresponding component in relation to the pump housing, in which all components of the component move in a circle around a common axis.

[0010] Preferably, an outer surface of the rotor, in particular an outer surface of the rotor base body, and an inner surface of the actuating element radially delimit a delivery region of the rotary pump. Axially, the delivery region can be defined by the axial extent of the delivery means. Within the delivery region, two adjacent delivery means, together with the outer surface of the rotor, in particular the outer surface of the rotor base body, and the inner surface of the actuating element, can form a delivery cell. Preferably, the cell volume of a delivery cell changes during operation of the rotary pump (when the delivery rotor rotates). The delivery region can have a low-pressure region and a high-pressure region. The low-pressure region is defined, for example, by the cell volume of the delivery cells increasing in the direction of rotation of the delivery rotor.The high pressure range is defined, for example, by the fact that the cell volume of the conveyor cells decreases in the direction of rotation of the conveyor rotor.

[0011] The low-pressure inlet preferably extends from a fluid connection on the outer wall of the pump housing to or into the delivery area, in particular to or into the low-pressure area. The fluid to be delivered can be supplied to the delivery area via the low-pressure inlet. Independently of this, the low-pressure inlet can have a plurality of sub-sections. For example, an inlet channel can be connected to the fluid connection in the flow direction of the fluid to be delivered. The inlet channel advantageously extends from the fluid connection to an outer circumferential surface of the actuating element. The inlet channel can be a passage or channel in the pump housing. From the outer circumferential surface of the actuating element, the inlet channel can merge into a supply section. The supply section can have one or more sub-channels and / or pockets and / or depressions and / or kidneys in the pump housing.These preferably enable an axial supply of fluid to the low-pressure region of the delivery area. Independently of this, the supply section can also comprise recesses and / or depressions in other components of the rotary pump, such as the actuating element, to enable a supply, in particular a radial supply, of fluid to the delivery area, in particular the low-pressure area.

[0012] The high-pressure outlet extends from the delivery area, in particular from the high-pressure area, to a fluid outlet on the outer wall of the pump housing. The pumped fluid can be discharged from the delivery area, in particular from the high-pressure area, via the high-pressure outlet. Independently of this, the high-pressure outlet can have several sub-sections. For example, an outlet section can adjoin the delivery area, in particular the high-pressure area, in the flow direction of the fluid to be pumped. The outlet section can be formed by one or more sub-channels, pockets, depressions and / or kidneys in the pump housing. These preferably enable axial discharge of the pumped fluid from the delivery area, in particular from the high-pressure area.Independently of this, the outlet section can also comprise recesses and / or depressions in other components of the rotary pump, such as the actuating element, to enable the fluid to be discharged, in particular radially, from the delivery area, in particular from the high-pressure area. Starting at the outer surface of the actuating element, the outlet area can transition into an outlet channel. The outlet channel advantageously extends from the outer surface of the actuating element to the fluid outlet. The outlet channel can be a passage or channel in the pump housing.

[0013] The actuating element, which is translationally movable back and forth with respect to the pump housing, can be moved translationally back and forth, in particular, between a first position and a second position. Preferably, the rotary pump has a maximum displacement in the first position. In the second position, the rotary pump preferably has a minimum displacement. The actuating element can be made of one piece. Preferably, it is molded in one piece.

[0014] The actuating element comprises, on the inlet side, i.e., for example, facing the low-pressure inlet, in particular the inlet channel, a first circumferential section and a second circumferential section. Both circumferential sections extend circumferentially in the direction of rotation of the conveyor rotor, with the second circumferential section adjoining, preferably directly adjoining, the first circumferential section in the direction of rotation of the conveyor rotor. The first circumferential section has an axial width that is smaller than the axial width of the conveyor means. According to the invention, the second circumferential section has an axial width that is greater than the axial width of the first circumferential section. The axial width of the second circumferential section can nevertheless be smaller than the axial width of the conveyor means. Preferably, however, the axial width of the second circumferential section corresponds at least substantially to the axial width of the conveyor means.The term "substantially" is understood here to mean a permissible deviation that does not exceed the manufacturing tolerances, in particular less than 0.5 mm.

[0015] The first circumferential section and the second circumferential section can at least partially radially delimit the conveying region, in particular the low-pressure region, in every position of the actuating element. In an exemplary embodiment, the first circumferential section is arranged at least partially radially between the conveying rotor and the inlet channel of the low-pressure inlet in every position of the actuating element. Alternatively or additionally, the second circumferential section is arranged at least partially radially between the conveying rotor and the inlet channel of the low-pressure inlet in every position of the actuating element. In a particularly advantageous embodiment, both the first circumferential section and the second circumferential section are arranged at least partially, preferably completely over the respective circumferential extent, radially between the conveying rotor and the inlet channel of the low-pressure inlet in every position of the actuating element.

[0016] The term "any position of the actuator" includes the first position, the second position, and any other position that the actuator may assume between the first and second positions.

[0017] In advantageous embodiments, the delivery region, in particular the low-pressure region of the delivery region, is directly connected to the low-pressure inlet, in particular the inlet channel, via the first circumferential section in a radial direction in a fluid-communicating manner. This fluid-communicating connection between the delivery region, in particular the low-pressure region, and the low-pressure inlet, in particular the inlet channel, is preferably present in every position of the actuating element. Alternatively or additionally, direct fluid communication between the delivery region, in particular its low-pressure region, and the low-pressure inlet, in particular the inlet channel, in the radial direction is prevented by the second circumferential section.The prevention of fluid communication between the delivery area, in particular the low-pressure area of ​​the delivery area, and the low-pressure inlet, in particular the inlet channel, by the second circumferential section is advantageously ensured in any position of the actuating element. Such an embodiment has the advantage that the fluid that has already been supplied to the delivery area, in particular its low-pressure area, via the first circumferential section cannot be forced radially outward from the delivery area via the second circumferential section due to centrifugal force.

[0018] The first circumferential section can be provided at the beginning of the low-pressure region in the direction of rotation of the conveyor rotor. Preferably, the first circumferential section extends over less than 70% of the circumferential extent of the low-pressure region in any position of the actuating element. Particularly preferably, the first circumferential section extends over less than 60% of the circumferential extent of the low-pressure region in any position of the actuating element. The circumferential extent of the first circumferential section can be greater than the maximum circumferential extent of two adjacent conveyor cells. In other words, the circumferential extent of the first circumferential section is preferably greater than the maximum circumferential distance between the two outermost conveyors of a total of three adjacent conveyors.Irrespective of this, the circumferential extension of the first circumferential section can be smaller than the maximum circumferential extension of three adjacent conveyor cells. The circumferential extension of the first circumferential section is advantageously smaller than the maximum circumferential distance between the two outermost conveyors of a total of four adjacent conveyors.

[0019] The second circumferential section can extend in the direction of rotation of the conveyor rotor to the end of the low-pressure region, and in principle also beyond the low-pressure region, as long as the conveyor cells do not increase in size again. Preferably, the second circumferential section extends over more than 30% of the circumferential extent of the low-pressure region in any position of the adjusting element. Particularly preferably, the second circumferential section extends over more than 40% of the circumferential extent of the low-pressure region in any position of the adjusting element. The circumferential extent of the second circumferential section can be greater than the maximum circumferential extent of a conveyor cell. In other words, the circumferential extent of the second circumferential section is preferably greater than the maximum circumferential distance between two adjacent conveyors.Irrespective of this, the extent of the second circumferential section measured in the circumferential direction can be smaller than the maximum circumferential extent of two adjacent conveyor cells. The extent of the second circumferential section measured in the circumferential direction is preferably smaller than the maximum circumferential distance between the two outermost conveyors of a total of three adjacent conveyors.

[0020] A transition from the first circumferential section to the second circumferential section is arranged in every position of the adjusting element in the low-pressure inlet. The transition can, for example, be a shoulder of the adjusting element parallel to the axis of rotation of the conveyor rotor. In such an embodiment, the transition has almost no extension in the circumferential direction. Alternatively, the transition can also be designed as a ramp. In other words, the transition from the first circumferential section to the second circumferential section in the direction of rotation of the conveyor rotor can occur through an increase in the axial width of the adjusting ring. In such an embodiment, the transition has an extension in the circumferential direction. The transition can be linear, concave and / or convex. A short transition in the circumferential direction, ideally step-shaped, is preferred.

[0021] For translational adjustment of the adjusting element, the adjusting element can have multiple sliding surfaces. Preferably, each sliding surface of the adjusting element rests against a corresponding sliding surface of the pump housing. When the adjusting element is adjusted, the sliding surfaces of the adjusting element can slide along corresponding sliding surfaces of the pump housing to enable and advantageously guide translational movements of the adjusting element with respect to the pump housing.

[0022] In an exemplary development, at least two sliding surfaces of the adjusting element are designed as sealing sliding surfaces. Each of the sealing sliding surfaces can comprise at least one sealing edge that faces the low-pressure inlet. Advantageously, the respective sealing edges seal the low-pressure inlet in the sliding contact between the pump housing and the adjusting element. For example, the adjusting element can have a first sealing sliding surface that is provided in the circumferential direction, in particular counter to the direction of rotation of the conveying rotor, next to the first circumferential section. In addition, the adjusting element can have a second sealing sliding surface that is provided in the circumferential direction, in particular in the direction of rotation of the conveying rotor, next to the second circumferential section. Independently of this, the first sealing sliding surface advantageously has a first sealing edge. The second sealing sliding surface can have a second sealing edge.

[0023] The first sealing sliding surface can define a first imaginary plane. For example, the first imaginary plane can be spanned by the first sealing edge of the first sealing sliding surface and another edge of the first sealing sliding surface that is orthogonal to the first sealing edge. The second sealing sliding surface can define a second imaginary plane. For example, the second imaginary plane can be spanned by the second sealing edge of the second sealing sliding surface and another edge of the second sealing sliding surface that is orthogonal to the second sealing edge. Advantageously, the first imaginary plane is aligned parallel to the second imaginary plane. The first imaginary plane can be aligned parallel, offset, or congruent with the second imaginary plane.

[0024] In an exemplary embodiment, the first imaginary plane extends in every position of the adjusting element between the axis of rotation of the conveyor rotor and the transition of the adjusting element. Preferably, the transition is neither intersected nor tangent to the first imaginary plane. Irrespective of this, the second imaginary plane can extend in every position of the adjusting element between the axis of rotation of the conveyor rotor and the transition. Preferably, the transition is neither intersected nor tangent to the second imaginary plane. In an exemplary development, both imaginary planes extend between the axis of rotation of the conveyor rotor and the transition. Advantageously, the transition is neither intersected nor tangent to the first imaginary plane nor the second imaginary plane.

[0025] The transition can have a distance from the first sealing edge measured in the circumferential direction, in particular counter to the direction of rotation of the conveyor rotor. This distance can be greater than or equal to a distance from the second sealing edge measured in the circumferential direction, in particular counter to the direction of rotation of the conveyor rotor. Preferably, the distance of the transition to the first sealing edge measured in the circumferential direction, in particular counter to the direction of rotation of the conveyor rotor, is greater than the distance of the transition to the second sealing edge measured in the circumferential direction, in particular in the direction of rotation of the conveyor rotor.

[0026] The distance between the transition and the first sealing edge, measured in the circumferential direction, in particular counter to the direction of rotation of the conveyor rotor, can be greater than the maximum circumferential extent of two adjacent conveyor cells. In other words, the distance between the transition and the first sealing edge, measured in the circumferential direction, in particular counter to the direction of rotation of the conveyor rotor, is preferably greater than the maximum circumferential distance between the two outermost conveyors of a total of three adjacent conveyors. Irrespective of this, the distance between the transition and the first sealing edge, measured in the circumferential direction, in particular counter to the direction of rotation of the conveyor rotor, can be smaller than the maximum circumferential extent of three adjacent conveyor cells.The distance between the transition and the first sealing edge measured in the circumferential direction, in particular against the direction of rotation of the conveyor rotor, is preferably smaller than the maximum circumferential distance between the two outermost conveyors of a total of four adjacent conveyors.

[0027] The distance between the transition and the second sealing edge, measured in the circumferential direction, in particular in the direction of rotation of the conveyor rotor, can be greater than the maximum circumferential extent of a conveyor cell. In other words, the distance between the transition and the second sealing edge, measured in the circumferential direction, in particular in the direction of rotation of the conveyor rotor, is preferably greater than the maximum circumferential distance between two adjacent conveyors. Irrespective of this, the distance between the transition and the second sealing edge, measured in the circumferential direction, in particular in the direction of rotation of the conveyor rotor, can be smaller than the maximum circumferential extent of two adjacent conveyor cells.The distance measured in the circumferential direction, in particular in the direction of rotation of the conveyor rotor, between the transition and the second sealing edge is preferably smaller than the maximum circumferential distance between the two outermost conveyor means of a total of three adjacent conveyor means.

[0028] The first circumferential section may have an axial recess. The recess preferably extends over the entire radial width of the first circumferential section. The circumferential extent of the first circumferential section may be defined by the circumferential extent of the recess. The recess preferably comprises a recess base that is delimited in the circumferential direction by two recess walls. One of the recess walls may be formed by the transition.

[0029] In an exemplary development, the second circumferential section has a recess. The recess is preferably open radially inward, toward the conveyor rotor. In the radial and / or axial direction, the recess is preferably not continuous. In other words, the recess does not extend over the entire axial and / or radial width of the second circumferential section. The recess can extend in the circumferential direction, in particular counter to the direction of rotation of the conveyor rotor, up to the first circumferential section. In the opposite circumferential direction, in particular in the direction of rotation of the conveyor rotor, the recess is advantageously delimited by a wall of the actuating element.The extent of the recess starting from the first circumferential section and measured in the circumferential direction, in particular in the direction of rotation of the conveyor rotor, can be less than or equal to a maximum circumferential distance between two adjacent conveyor means, but is preferably greater than a maximum circumferential distance between two adjacent conveyor means.

[0030] During operation of the rotary pump, the fluid to be pumped can flow, for example, from the low-pressure inlet via the first circumferential section into the recess. The recess can be designed such that the fluid located in the recess has a tangential flow direction with respect to the conveying rotor. Advantageously, the conveying means rotating past the recess indirectly accelerate the fluid located in the recess in the direction of rotation of the conveying rotor. The fluid accelerated in the circumferential direction in the recess can then be introduced into the conveying region, in particular into the low-pressure region, via the delimiting wall. Advantageously, indirect fluid communication is brought about via the recess in the second circumferential section between the low-pressure inlet, in particular the inlet channel, and the conveying region, in particular the low-pressure region.

[0031] The recess is radially delimited by an outer wall of the second circumferential section, so that fluid flowing tangentially into the recess is accelerated along the outer wall in the circumferential direction, but cannot be pushed back into the low-pressure inlet. The actuating element can have an axial width in the region of the outer wall that corresponds to the axial width of the conveying means, as is preferred. In principle, however, the outer wall can also have an axial width that is smaller than the axial width of the conveying means. However, the axial width of the outer wall is greater than the axial width of the first circumferential section of the actuating element. The actuating element can have a recess over the length of the second circumferential section measured in the circumferential direction from radially outside to inside, so that the actuating element drops gradually from the axial width of the outer wall to the comparatively smaller axial width of the recess.Although such a profile is preferred, in principle the adjusting element in the second circumferential section can instead slope from radially outside to inside in a ramp-like manner, obliquely or with a convex or concave round curvature.

[0032] In advantageous embodiments, the rotary pump can have a flow-guiding structure to influence the fluid flowing in the low-pressure inlet, in particular to change its direction. The flow-guiding structure preferably projects axially from the pump housing into the low-pressure inlet. It can, in particular, be a structure of the pump housing. The flow-guiding structure can be wedge-shaped or tapered, counter to the flow direction of the fluid in the low-pressure inlet. Advantageously, the flow-guiding structure directs a first partial flow of the fluid flow in the low-pressure inlet such that, upon passing through the actuating element, the first partial flow has a main flow direction that is counter to the direction of rotation of the conveying rotor.Alternatively or additionally, the flow guide structure can be shaped such that a second partial flow of the fluid flow in the low-pressure inlet, when passing the actuating element, has a main flow direction that corresponds to the direction of rotation of the conveyor rotor. Independently of this, the flow guide structure can be shaped such that the first partial flow of the fluid flow in the low-pressure inlet is directed in the direction of the first circumferential section. Alternatively or additionally, the flow guide structure can be shaped such that the second partial flow of the fluid flow in the low-pressure inlet is directed in the direction of the second circumferential section. The flow guide structure, if present, thus divides the low-pressure inlet into a first partial inlet channel, which directs the fluid to the first circumferential section of the actuating element, and a second partial inlet channel, which directs the fluid to the second circumferential section of the actuating element.

[0033] As already explained, the transition from the first circumferential section to the second circumferential section is arranged in the low-pressure inlet in every position of the control element. If the rotary pump has the flow-guiding structure, the transition can advantageously be arranged next to the flow-guiding structure in the region of the second partial inlet channel in every position of the control element in an axial plan view of the flow-guiding structure.

[0034] The actuating element forms an axial sealing gap with axially facing end faces of the pump housing on both end sides of the actuating element, which seals the delivery area radially outwards over the circumference of the actuating element within the scope of the actuating element's mobility.

[0035] The pump housing can have one or more axial recesses in the area of ​​the low-pressure inlet. Each housing recess axially widens the low-pressure inlet. The respective housing recess can extend on the facing end face of the actuating element below the actuating element into the low-pressure region of the delivery area into an optionally present inlet kidney, which can extend as an axial housing recess axially next to and, in this sense, below the delivery elements in the circumferential direction. In such embodiments, the fluid flows in the respective housing recess past the actuating element into the inlet kidney. The inlet kidney, if present, can extend in the circumferential direction along the first circumferential section of the actuating element and / or along the second circumferential section of the actuating element.

[0036] If the inlet kidney extends along the first circumferential section and a housing recess of the low-pressure inlet extends on an end face of the actuating element below the first circumferential section into the inlet kidney, fluid in the housing recess can flow past the first circumferential section into the inlet kidney and from there axially into the delivery area.

[0037] If the inlet kidney extends along the second circumferential section and a housing recess of the low-pressure inlet extends into the inlet kidney on an end face of the actuating element below the second circumferential section, fluid can flow past the second circumferential section into the inlet kidney and from there axially into the delivery area. If the axial width of the second actuating element circumferential section in such embodiments corresponds to the width of the delivery means, the actuating element prevents radial inflow into the delivery area in its second circumferential section. However, in such embodiments, fluid can flow from the side via the part of the inlet kidney extending along the second circumferential section and thus axially into the delivery area.If the axial width of the second actuating element circumferential section is smaller than the width of the conveying means, but larger than the axial width of the first circumferential section, a radial inflow through the second circumferential section is at least throttled compared to the first circumferential section. A backflow due to centrifugal force is at least counteracted in the second circumferential section due to the larger axial width compared to the first circumferential section, as per the invention.

[0038] The rotary pump can be intended in particular for use in a motor vehicle. Accordingly, the rotary pump can be designed as a motor vehicle pump. The rotary pump is preferably intended for conveying a liquid, in particular a lubricating, cooling and / or actuating agent. Accordingly, the rotary pump can be designed as a liquid pump. The rotary pump is preferably intended for supplying and / or lubricating and / or cooling a drive motor and / or a transmission of a motor vehicle. The liquid is preferably an oil, for example an engine lubricating oil or transmission oil. The rotary pump can be designed in particular as an engine lubricant pump for a motor vehicle and / or as a transmission pump for a motor vehicle.

[0039] The features described above can be combined with one another in any way, provided this is technically reasonable and suitable. Further features, feature combinations, and advantages of the invention will become apparent from the following description of exemplary embodiments with reference to the figures. They show: Figure 1 is a sectional view of an embodiment of the rotary pump according to the invention; Figure 2 is a perspective view of the Figure 1 shown sectional view; Figure 3 a perspective view of an adjusting element of the Figure 1 shown embodiment; Figure 4 a plan view of the Figure 3 shown adjusting element; Figure 5 a first sectional view of the Figure 3 shown adjusting element; Figure 6 a second sectional view of the Figure 3 shown adjusting element; and Figure 7 shows a section of a side view of the Figure 1 shown embodiment.

[0040] Figure 1is a sectional view of an embodiment of the rotary pump 1 according to the invention. In the embodiment, the rotary pump 1 is designed as a vane pump. The rotary pump 1 has a pump housing 2, which comprises a low-pressure inlet 3 and a high-pressure outlet 4 for the fluid to be pumped. In order to guide the fluid to be pumped into the interior of the rotary pump 1, the low-pressure inlet 3 has a fluid connection 3a on an outer wall of the pump housing 2. The fluid connection 3a forms an inlet opening for an inlet channel 3b of the low-pressure inlet 3. The inlet channel 3b extends from the fluid connection 3a into the pump housing 2. Analogously, the high-pressure outlet 4 has an outlet channel 4a in order to guide the fluid out of the rotary pump via a fluid connection of the high-pressure outlet 4 (not shown).

[0041] Arranged within the pump housing 2 is a conveying rotor 5 which can rotate about an axis of rotation D. The conveying rotor 5 is axially delimited by the pump housing 2. A plurality of conveying means 6 are distributed over the circumference of the conveying rotor 5. In the illustrated embodiment, the conveying means 6 can move back and forth radially outwards and inwards with respect to the axis of rotation D. The conveying means 6 are arranged at equal distances from one another in the circumferential direction. Alternatively or additionally, the conveying means 6 can be arranged at different distances from one another in the circumferential direction, at least in sections. The movement of the conveying means 6 is limited radially inwards by the conveying rotor 5. The movement of the conveying means 6 outwards, away from the axis of rotation D, is limited by an inner circumferential surface 16 of an actuating element 10.

[0042] During operation of the rotary pump 1, the conveying rotor 5 rotates about the axis of rotation D. The conveying means 6 are pressed radially outwards towards the inner circumferential surface 16 of the actuating element 10 due to the centrifugal force acting on the conveying means 6. Together with the outer circumferential surface 5a of the conveying rotor 5 and the inner circumferential surface 16 of the actuating element 10, the axial outer edges of the conveying means 6 define a conveying region. The conveying region is thus an annular volume whose axial width corresponds to the width of the conveying means 6. Within the conveying region, two adjacent conveying means 6 form a conveying cell 6a. The conveying region or the conveying cells 6a are supplied with the fluid to be conveyed via the low-pressure inlet 3, in particular via the fluid connection 3a and the inlet channel 3b. In the conveying region, the fluid to be conveyed is conveyed from the low-pressure inlet 3 to the high-pressure outlet 4, in particular to the outlet channel 4a.The fluid to be conveyed is conveyed in the conveying cells 6a under the direct influence of the rotating conveying means 6 from the low-pressure inlet 3 through the conveying area to the high-pressure outlet 4.

[0043] The control element 10, whose detailed structure is described below and based on the Figures 3-6will be described in more detail, is designed to change or adjust the delivery volume of the rotary pump 1. For this purpose, the actuating element 10 can be moved back and forth between at least two positions with respect to the pump housing 2. In the exemplary embodiment, the actuating element 10 can be moved in translation. This means that the actuating element 10 is arranged in the pump housing 2 so that it can be displaced. The inner circumferential surface 16 of the actuating element 10 extends around a central axis (not shown), which in a first position of the actuating element 10 is offset parallel to the axis of rotation D of the delivery rotor 5. Due to the parallel offset of the central axis of the actuating element 10 with respect to the axis of rotation D of the delivery rotor 5, the actuating element 10 has an eccentricity with respect to the delivery rotor 5. Figure 1 shows the control element 10 in the first position.

[0044] In the first position, the delivery range comprises a low-pressure range in which the volume of the delivery cells 6a increases in the direction of rotation of the delivery rotor 5. Furthermore, in the first position of the actuating element 10, the delivery range comprises a high-pressure range that adjoins the low-pressure range in the direction of rotation of the delivery rotor 5. In the high-pressure range, the volume of the delivery cells 6a decreases in the direction of rotation of the delivery rotor 5. The rotary pump 1 has a maximum delivery volume in the first position.

[0045] In a second position (not shown), the adjusting element 10 is displaced within the pump housing 2 such that the adjusting element 10 exhibits minimal or no eccentricity with respect to the delivery rotor 5. In other words, the center axis of the adjusting element 10 in the second position is substantially or almost coaxial with the rotational axis D of the delivery rotor 5. The rotary pump 1 exhibits a minimal delivery volume in the second position.

[0046] The first and second positions are preferably end positions of the actuating element 10. This means that the actuating element 10 cannot assume a position in which the actuating element 10 has a greater eccentricity with respect to the conveyor rotor 5 than in the first position, and / or that the actuating element 10 cannot have a lesser eccentricity with respect to the conveyor rotor 5 than in the second position. Between the first position and the second position, the actuating element 10 can assume several, for example any number, intermediate positions.

[0047] The rotary pump 1 comprises a return means 7 for pressing the actuating element 10 into the first position. Preferably, the return means 7 exerts a return force on the actuating element 10, wherein the return force presses the actuating element 10 into the first position. In the illustrated embodiment, the return means 7 has two return springs 7, which are supported on the one hand on the pump housing 2 and on the other hand on a pressure surface 21 of the actuating element 10. In order to move the actuating element 10 into the second position, the rotary pump 1 comprises a pressure channel 23 and a pressure chamber 24. The pressure chamber 24 extends between the pump housing 2 and the actuating element 10. A pressurized fluid can be conducted into the pressure chamber 24 via the pressure channel 23. The fluid pressure thus prevailing in the pressure chamber 24 presses the actuating element 10 against the restoring force of the restoring means 7 in the direction of the second position.The pressurized fluid may, for example, be the pumped fluid which is taken from a point in the high-pressure area still within the pump housing 2 or from a point downstream of the high-pressure outlet 4.

[0048] On the inlet side, i.e., in the area of ​​the low-pressure inlet 3, the actuating element 10 comprises a first circumferential section 11 and a second circumferential section 13. Independently of this, the conveying area is at least partially delimited or enclosed radially outwardly by the first circumferential section 11 and the second circumferential section 13. The second circumferential section 13 adjoins the first circumferential section 11 in the direction of rotation of the conveying rotor 5. Both circumferential sections 11, 13 extend radially between the inner circumferential surface 16 and an outer circumferential surface 17 of the actuating element 10.

[0049] The first circumferential section 11 has an axial width B 1 which is smaller than the axial width of the conveying means 6. The second circumferential section 13 has an axial width B 2 which is greater than the axial width B 1 of the first circumferential section 11 (cf. Figures 3 and 5 ). Preferably, the axial width B 2 of the second circumferential portion 13 corresponds to the axial width of the conveying means 6.

[0050] An extension of the first circumferential section 11 measured in the circumferential direction is greater than or equal to the circumferential extension of the second circumferential section 13. In the Figure 1 In the embodiment shown, the extent of the first circumferential section 11 measured in the circumferential direction is greater than the circumferential extent of the second circumferential section 13.

[0051] As in Figure 1As shown, the extent of the first circumferential section 11 measured in the circumferential direction is greater than the maximum circumferential extent of two adjacent conveyor cells 6a. In other words, the extent of the first circumferential section 11 measured in the circumferential direction is greater than the maximum circumferential distance between the two outermost conveyor means 6 of a total of three adjacent conveyor means 6. Independently of this, the extent of the first circumferential section 11 measured in the circumferential direction is smaller than the maximum circumferential extent of three adjacent conveyor cells 6a. The extent of the first circumferential section 11 measured in the circumferential direction is smaller than the maximum circumferential distance between the two outermost conveyor means 6 of a total of four adjacent conveyor means 6.

[0052] The circumferential extension of the second circumferential section 13 is greater than the maximum circumferential extension of one conveyor cell 6a. In other words, the circumferential extension of the second circumferential section 13 is greater than the maximum circumferential distance between two adjacent conveyors 6. Independently of this, the circumferential extension of the second circumferential section 13 is smaller than the maximum circumferential extension of two adjacent conveyor cells 6a. The circumferential extension of the second circumferential section 13 is smaller than the maximum circumferential distance between the two outermost conveyors 6 of a total of three adjacent conveyors 6.

[0053] During operation of the rotary pump 1, the fluid to be pumped can flow around the first circumferential section 11 in the radial direction in order to flow radially into the delivery area of ​​the rotary pump 1. The delivery area of ​​the rotary pump 1 is directly connected in a radial fluid communication manner to the low-pressure inlet 3, in particular to the inlet channel 3a of the low-pressure inlet 3, via the first circumferential section 11. The first circumferential section 11 advantageously ensures that the delivery cells 6a are optimally flooded with the fluid to be pumped at the beginning of the low-pressure area, in particular in a first section of the low-pressure area.

[0054] The first circumferential section 11 is formed by a recess 12 in the actuating element 10, in particular an axial recess 12. The recess 12 is continuous in the radial direction.

[0055] In the direction of rotation of the conveyor rotor 5, the first circumferential section 11 extends to a transition 15. In the exemplary embodiment, the transition 15 is a shoulder 15 and can in particular be a shoulder 15 parallel to the axis of rotation D of the conveyor rotor 5. The transition 15 connects the first circumferential section 11 to the second circumferential section 13. In other words, the transition 15 defines the boundary between the first circumferential section 11 and the second circumferential section 13. In the exemplary embodiment shown, the transition 15 is arranged in the low-pressure inlet 3 in every position of the actuating element 10. The transition 15 is arranged within the extension range of the low-pressure inlet 3 measured in the circumferential direction in every position of the actuating element 10 and can preferably be subjected to flow by the fluid flowing in the low-pressure inlet 3 in every position of the actuating element 10.The transition 15 is arranged radially between the conveyor rotor 5 and a section of the low-pressure inlet 3, in particular the inlet channel 3b, in each position of the actuating element 10.

[0056] The fluid to be conveyed, which flows into the delivery cells 6a during operation of the rotary pump 1 at the beginning of the low pressure range, is exposed to a centrifugal force which increases in the direction of rotation of the delivery rotor 5 due to the entrainment by the delivery means 6. This centrifugal force acting on the fluid causes the fluid to be pushed radially outwards with increasing force in the direction of rotation of the conveyor rotor 5. Further flooding of the conveyor cells 6a from a radial direction becomes increasingly difficult in the direction of rotation of the conveyor rotor 5. Rather, the fluid even tends to be pushed out of the delivery cells 6a again. This effect occurs in particular towards the end of the low-pressure region, i.e. in particular in a second peripheral section 13 of the low-pressure region or of the adjusting element 10 which adjoins the first peripheral section 11 in the direction of rotation of the conveyor rotor 5.

[0057] The second circumferential section 13 is shaped such that a radial outflow of the fluid from the conveying cells 6a is hindered or advantageously prevented. In other words, the second circumferential section 13 hinders or prevents direct fluid communication between the conveying area and the low-pressure inlet 3, in particular the inlet channel 3b of the low-pressure inlet 3, in the radial direction. In advantageous embodiments, the axial width B 2 of the second circumferential section 13 corresponds at least substantially to the axial width of the conveying means 6.

[0058] In the exemplary embodiment, the second circumferential section 13 comprises a recess 14. The recess 14 is an axial depression in the second circumferential section 13. The recess 14 is open radially inward, i.e., toward the inner circumferential surface 16 of the actuating element 10, and is delimited radially outward by an outer wall of the actuating element 10. The actuating element 10 drops axially in a step-like manner from the delimiting outer wall to a bottom of the recess 14, so that the strip-shaped recess 14 is obtained around the conveying means 6 running past inside over the length of the second circumferential section 13, measured in the circumferential direction.

[0059] In the circumferential direction, the recess 14 extends counter to the direction of rotation of the conveyor rotor 5 up to the first circumferential section 11. In the direction of rotation of the conveyor rotor 5, the recess 14 is delimited by a wall 14a.

[0060] The fluid to be conveyed can flow from the low-pressure inlet 3 into the recess 14 via the first circumferential section 11. The fluid located in the recess 14 has a primarily tangential flow direction with respect to the conveying rotor 5. The conveying means 6 rotating past the recess 14 accelerate the fluid located in the recess 14 in the direction of rotation of the conveying rotor 5. However, an outer wall of the actuating element 10 radially delimiting the recess 14 retains the fluid. The fluid accelerated in the recess 14 is then directed in the region of the wall 14a into the conveying region, in particular into the low-pressure region, of the rotary pump 1. The recess 14 enables indirect fluid communication between the conveying region and the low-pressure inlet 3 via the second circumferential section 13.The recess 14, which is delimited radially on the outside by the outer wall of the actuating element 10, improves the filling of the conveyor cells 6a in the second circumferential section 13.

[0061] The rotary pump 1 comprises a flow guide structure 22, which is arranged in the low-pressure inlet 3. The flow guide structure 22 projects axially from a wall of the pump housing 2 into the low-pressure inlet 3 with respect to the axis of rotation D of the conveying rotor 5. The flow guide structure 22 is preferably designed to influence the fluid flow flowing in the low-pressure inlet 3, in particular the fluid flowing in the inlet channel 3b. In the exemplary embodiment, the fluid flow is influenced by the flow guide structure 22 in such a way that its direction is changed, or at least partially changed, by the flow guide structure 22. A first partial flow of the fluid is influenced or deflected by the flow guide structure 22 in such a way that its direction is changed, or at least partially changed, by the flow guide structure 22 in such a way that the first partial flow receives at least one flow direction component that is opposite to the direction of rotation of the conveying rotor 5. A second partial flow of the fluid is influenced or deflected by the flow guide structure 22 in such a way that its direction is changed, or at least partially changed, by thedeflected so that the second partial flow receives at least one flow component which corresponds to the direction of rotation of the conveyor rotor 5.

[0062] The flow guide structure 22, together with the pump housing 2, forms a first partial inlet channel 3c that is axially open on one side. During operation of the rotary pump 1, the first partial flow of the fluid flow preferably flows through the first partial inlet channel 3c. In the direction of rotation of the conveying rotor 5, a second partial inlet channel 3d is arranged next to the first partial inlet channel 3c. The second partial inlet channel 3d is axially open on one side and is formed by the flow guide structure 22 and the pump housing 2. During operation of the rotary pump 1, the second partial flow of the fluid preferably flows through the second partial inlet channel 3d. In other words, the flow guide structure 22 projects axially into the low-pressure inlet 3 such that it is arranged between the first partial inlet channel 3c and the second partial inlet channel 3d. The flow guide structure 22 separates the first partial inlet channel 3c from the second partial inlet channel 3d in the circumferential direction.

[0063] The flow guide structure 22 extends axially only from one side of the pump housing 2 into the low-pressure inlet 3, thus not extending across the full axial width of the low-pressure inlet 3. Fluid can thus also flow over the flow guide structure 22. In principle, however, the flow guide structure 22 could also extend axially almost completely through the low-pressure inlet 3.

[0064] The first circumferential section 11 is arranged axially next to and / or in the first partial inlet channel 3c in every position of the actuating element 10. The second circumferential section 13 is arranged axially next to and / or in the second partial inlet channel 3d in every position of the actuating element 10. The transition 15 is arranged axially next to the flow guide structure 22 and / or axially next to the second partial inlet channel 3d in every position of the actuating element 10. Alternatively or additionally, the transition 15 can be arranged radially next to the flow guide structure 22 and / or in the second partial inlet channel 3d in every position of the actuating element 10.

[0065] For the translational adjustment of the adjusting element 10, the adjusting element 10 comprises several sealing sliding surfaces 18, 19. The sealing sliding surfaces 18, 19 each rest against a sliding surface 8, 9 of the pump housing 2. When the adjusting element 10 is adjusted, the sealing sliding surfaces 18, 19 slide along the respective sliding surface 8, 9. The sealing sliding surfaces 18, 19 comprise sealing edges 18a, 19a that face the low-pressure inlet 3. The sealing edges 18a, 19a seal the low-pressure inlet 3 at the transition from the pump housing 2 to the adjusting element 10.

[0066] In the Figure 1 In the embodiment shown, the adjusting element 10 comprises a first sealing sliding surface 18 with a first sealing edge 18a ( Fig. 3). The first sealing sliding surface 18 rests against a first sliding surface 8 of the pump housing 2. A second sealing sliding surface 19 of the actuating element 10 has a second sealing edge 19a. The second sealing sliding surface 19 rests against a second sliding surface 9 of the pump housing 2. The first sealing sliding surface 18 is arranged circumferentially opposite to the direction of rotation of the conveying rotor 5 next to the first circumferential section 11. The second sealing sliding surface 19 is arranged circumferentially in the direction of rotation of the conveying rotor 5 next to the second circumferential section 13.

[0067] The transition 15 has a distance measured in the circumferential direction from the first sealing edge 18a that is greater than or equal to a distance measured in the circumferential direction from the second sealing edge 19a. In the Figure 1In the embodiment shown, the distance of the transition 15 to the first sealing edge 18a measured in the circumferential direction is greater than the distance of the transition 15 to the second sealing edge 19a measured in the circumferential direction.

[0068] The distance measured in the circumferential direction between the transition 15 and the first sealing edge 18a is greater than the maximum circumferential extent of two adjacent conveyor cells 6a. In other words, the distance measured in the circumferential direction between the transition 15 and the first sealing edge 18a is greater than the maximum circumferential distance between the two outermost conveyor means 6 of a total of three adjacent conveyor means 6. Independently of this, the distance measured in the circumferential direction between the transition 15 and the first sealing edge 18a is smaller than the maximum circumferential extent of three adjacent conveyor cells 6a. The distance measured in the circumferential direction between the transition 15 and the first sealing edge 18a is smaller than the maximum circumferential distance between the two outermost conveyor means 6 of a total of four adjacent conveyor means 6.

[0069] The distance measured in the circumferential direction between the transition 15 and the second sealing edge 19a is greater than the maximum circumferential extension of one conveyor cell 6a. In other words, the distance measured in the circumferential direction between the transition 15 and the second sealing edge 19a is greater than the maximum circumferential distance between two adjacent conveyors 6. Independently of this, the distance measured in the circumferential direction between the transition 15 and the second sealing edge 19a is smaller than the maximum circumferential extension of two adjacent conveyor cells 6a. The distance measured in the circumferential direction between the transition 15 and the second sealing edge 19a is smaller than the maximum circumferential distance between the two outermost conveyors 6 of a total of three adjacent conveyors 6.

[0070] Preferably, the first sealing sliding surface 18 defines a first imaginary plane (not shown). The second sealing sliding surface 19 defines a second imaginary plane (not shown). The two imaginary planes extend parallel to one another in the direction of movement of the actuating element 10. In the exemplary embodiment, the second imaginary plane is offset parallel to the first imaginary plane. In particular, the second imaginary plane has an orthogonal distance to the axis of rotation D that is greater than the orthogonal distance between the first imaginary plane and the axis of rotation D. In alternative exemplary embodiments, however, the two planes can also be arranged congruently with one another. Both imaginary planes extend in every position of the actuating element 10 between the axis of rotation D of the conveyor rotor 5 and the transition 15.

[0071] For a better understanding, the Figure 1 shown sectional view of the rotary pump 1 in Figure 2shown in perspective. To explain the structure and function of the Figure 2 For the rotary pump 1 shown, reference is made to the above explanations.

[0072] Figure 3 shows a perspective view of the adjusting element 10 of the exemplary embodiment. However, the adjusting element 10 can also be used in other rotary pumps with adjustable displacement. The adjusting element 10 is preferably one-piece and can, in particular, be molded in one piece.

[0073] The adjusting element 10 is delimited radially outwardly by an outer surface 17 and radially inwardly by an inner surface 16. In addition, two pressure surfaces 21 are formed on the adjusting element 10, on each of which a return means 7 of the rotary pump 1 can be supported (return means 7 in Figure 3 not shown). In alternative embodiments, the actuating element 10 may also have only one pressure surface 21 or more than two pressure surfaces 21.

[0074] In the Figure 3 In the perspective view shown, the first sealing sliding surface 18 and the second sealing sliding surface 19 are visible. On the opposite side of the actuating element 10, on the side of the high-pressure outlet, the actuating element 10 comprises two further sealing sliding surfaces, which are preferably each designed analogously to the first sealing sliding surface 18 and the second sealing sliding surface 19.

[0075] The edge of the first sealing sliding surface 18 facing the first circumferential section 11 forms the first sealing edge 18a. The edge of the second sealing sliding surface 19 facing the second circumferential section 13 forms the second sealing edge 19a.

[0076] The first circumferential section 11 has an axial width B 1 which is smaller than the axial width B 2 of the second circumferential section 13. In the circumferential direction, the first circumferential section 11 is separated from the second circumferential section 13 by the transition 15.

[0077] The first circumferential section 11 is formed by at least one recess 12 or, as shown in the illustrated embodiment, two axially opposite recesses 12. The recess 12 comprises a recess base 12a. The edge 12c, which connects the outer circumferential surface 17 to the recess base 12a, is preferably rounded or has a radius. A rounded edge 12c results in a less turbulent radial inflow of the fluid to be pumped from the low-pressure inlet 3 into the delivery area of ​​the rotary pump 1. In the circumferential direction, the recess base 12a is delimited by a respective recess wall 12b. The recess wall 12b arranged in the direction of rotation of the delivery rotor 5 simultaneously forms the transition 15.

[0078] The transition 15 is a shoulder 15 of the adjusting element 10. The shoulder 15 extends from the first circumferential section 11, in particular from the recess base 12a, vertically in the axial direction.

[0079] The second circumferential section 13, which adjoins the conveyor rotor 5 in the direction of rotation, has a width B 2 corresponding to the axial width of the conveyor means 6. The second circumferential section 13 comprises a recess 14 on the side of the inner circumferential surface 16. The recess 14 extends in the circumferential direction from the first circumferential section 11 and / or from the transition 15 to a wall 14a.

[0080] In the Figure 3 In the embodiment of the actuating element 10 shown, a pressure recess 25 is provided in the second sealing sliding surface 19. In the installed state of the actuating element 10, the pressure recess 25 is fluidly connected to the pressure chamber 24 via a channel 26.

[0081] For a better understanding, the control element 10 is in Figure 4 shown in a top view. Figure 5 and Figure 6 show the Figure 4drawn sections of the control element 10. With regard to the concrete structure of the control element 10, reference is made to the above explanations.

[0082] Figure 7 shows a section of a side view of the rotary pump 1. In the Figure 7 In the section shown, the observer looks through the low-pressure inlet 3 in the flow direction of the fluid to be pumped into the pump housing 2.

[0083] The fluid to be pumped enters the inlet channel 3b of the low-pressure inlet 3 via the fluid connection 3a. A first portion of the inflowing fluid can flow directly, preferably in a radial direction, toward the actuating element 10, in particular toward the outer circumferential surface 17 of the actuating element 10. The fluid can flow into the pumping area via the first circumferential section 11, in particular radially or at least with a radial directional component, and be pumped by the pumping means 6.

[0084] The second circumferential section 13 adjoins the first circumferential section 11 in the direction of rotation of the conveying rotor 5. The second circumferential section 13 has an axial width corresponding to the axial width of the conveying means 6. As a result, the second circumferential section 13 advantageously prevents the fluid to be conveyed from flowing radially out of the conveying area again due to the increasing centrifugal force.

[0085] A second portion of the inflowing fluid strikes the flow guide structure 22. The flow guide structure 22 directs a partial flow of the second portion of the fluid into the first partial inlet channel 3c. Another partial flow of the second portion of the fluid is directed by the flow guide structure 22 into the second partial inlet channel 3d.

[0086] In the exemplary embodiment, the first circumferential section 11 is arranged axially next to, in particular also axially above, the first partial inlet channel 3c in every position of the actuating element 10. The second circumferential section 13 is arranged axially next to, in particular also axially above, the second partial inlet channel 3d in every position of the actuating element 10. Depending on the position of the actuating element 10, the transition 15 is arranged either axially next to, in particular axially above, the flow guide structure 22 and / or the second partial inlet channel 3d. Reference symbol:

[0087] 1 Rotary pump 13 second circumferential section 2 Pump housing 14 recess 3 Low pressure inlet 14a wall 3a Fluid connection 15 transition 3b Inlet channel 16 inner surface 3c first partial inlet channel 17 Outer surface 3d second partial inlet channel 18 first sealing sliding surface 4 High pressure outlet 18a first sealing edge 4a exhaust channel 19 second sealing sliding surface 5 conveyor rotor 19a second sealing edge 5a Outer surface 20 - 6 Funding 21 Print area 6a conveyor cells 22 Flow control structure 7 Restoring agent 23 pressure channel 8 first sliding surface 24 pressure chamber 9 second sliding surface 25 pressure recess 10 Actuator 26 channel 11 first circumferential section 12 Deepening 12a Reason for further study D axis of rotation 12b recess wall B 1 axial width 12c edge B 2 axial width

Claims

1. A rotary pump (1) having an adjustable delivery volume, the rotary pump (1) comprising: (a) a pump housing (2) having a low-pressure inlet (3) and a high-pressure outlet (4) for a fluid to be delivered; and (b) a delivery rotor (5) arranged such that it can be rotated about a rotational axis (D) in the pump housing (2) and comprising multiple delivery means (6) which are distributed over the circumference of the delivery rotor (5) for delivering the fluid from the low-pressure inlet (3) to the high-pressure outlet (4); and (c) a setting element (10) which can be translationally moved back and forth in relation to the pump housing (2) for adjusting the delivery volume of the rotary pump (1), wherein (d) the inlet end of the setting element (10) comprises (d1) a first circumferential portion (11) which extends circumferentially in the rotational direction of the delivery rotor (5) and the axial width (B1) of which is smaller than the axial width of the delivery means (6) and (d2) a second circumferential portion (13) which adjoins the first circumferential portion (11) in the rotational direction of the delivery rotor (5) and the axial width (B2) of which is greater than the axial width (B1) of the first circumferential portion (11), wherein (e) a transition (15) from the first circumferential portion (11) to the second circumferential portion (13) is arranged in the low-pressure inlet (3) in each position of the setting element (10), (f) wherein the first circumferential portion (11) and the second circumferential portion (13) are each at least partially arranged radially between the delivery rotor (5) and an inlet channel (3b) of the low-pressure inlet (3).

2. The rotary pump (1) according to claim 1, wherein the axial width (B2) of the second circumferential portion (13) is smaller than the axial width of the delivery means (6) or preferably corresponds to the axial width of the delivery means (6).

3. The rotary pump (1) according to any one of the preceding claims, wherein the transition (15) is a collar (15) of the setting element (10) which is parallel to the rotational axis (D) of the delivery rotor (5).

4. The rotary pump (1) according to any one of the preceding claims, wherein an outer surface area (5a) of the delivery rotor (5), an inner surface area (16) of the setting element (10) and the axial outer edges of the delivery means (6) define a delivery region of the rotary pump (1) while the rotary pump (1) is in operation, and the delivery region is connected in direct fluid communication with the low-pressure inlet (3) via the first circumferential portion (11) in the radial direction, and the second circumferential portion (13) prevents direct fluid communication between the delivery region and the low-pressure inlet (3) in the radial direction.

5. The rotary pump (1) according to claim 4, wherein the delivery region comprises a low-pressure region into which the fluid to be delivered flows, wherein the first circumferential portion (11) is arranged at the beginning of the low-pressure region in the rotational direction of the delivery rotor (5) and extends over less than 70% of the circumferential extent of the low-pressure region, preferably less than 60% of the circumferential extent of the low-pressure region, in any position of the setting element (10).

6. The rotary pump (1) according to any one of the preceding claims, wherein the setting element (10) comprises a first sealing sliding surface (18), which is in sliding contact with the pump housing (2) and is provided next to the first circumferential portion (11), and a second sealing sliding surface (19) which is in sliding contact with the pump housing (2) and is provided next to the second circumferential portion (13), wherein the first sealing sliding surface (18) and the second sealing sliding surface (19) slide along the pump housing (2) when the setting element (10) is translationally adjusted.

7. The rotary pump (1) according to claim 6, wherein the first sealing sliding surface (18) defines a first imaginary plane and the second sealing sliding surface (19) defines a second imaginary plane, wherein the first imaginary plane is embodied to be parallel to the second imaginary plane, and both planes extend between the rotational axis (D) of the delivery rotor (5) and the transition (15) in each position of the setting element (10) and preferably neither intersect nor are tangential to the transition (15).

8. The rotary pump (1) according to claim 6 or claim 7, wherein the first sealing sliding surface (18) comprises a first sealing edge (18a) at an end facing the second sealing sliding surface (19), and the second sealing sliding surface (19) comprises a second sealing edge (19a) at an end facing the first sealing sliding surface (18), and the sealing edges (18a, 19a) each seal off the low-pressure inlet (3) in the sliding contact between the pump housing (2) and the setting element (10), wherein the transition (15) exhibits a distance from each of the sealing edges (18a, 19a) as measured in the circumferential direction which is greater than or equal to a maximum distance between two adjacent delivery means (6) as measured in the circumferential direction.

9. The rotary pump (1) according to any one of claims 6 to 8, wherein the transition (15) exhibits a distance from the first sealing edge (18a) as measured in the circumferential direction which is greater than or equal to a distance from the second sealing edge (19a) as measured in the circumferential direction.

10. The rotary pump (1) according to any one of the preceding claims, wherein the first circumferential portion (11) and the second circumferential portion (13) exhibit a circumferential extent which corresponds to at least a maximum distance between two adjacent delivery means (6) as measured in the circumferential direction.

11. The rotary pump (1) according to any one of the preceding claims, wherein the first circumferential portion (11) exhibits a circumferential extent which is smaller than a maximum distance between the two outermost delivery means (6) of a total of four adjacent delivery means (6) as measured in the circumferential direction.

12. The rotary pump (1) according to any one of the preceding claims, wherein the first circumferential portion (11) is formed by a radially continuous, axial recess (12) in the setting element (10).

13. The rotary pump (1) according to claim 12, wherein the recess (12) comprises a recess base (12a) which is delineated in the circumferential direction by two opposing recess walls (12b), and one of the recess walls (12b) forms the transition (15).

14. The rotary pump (1) according to any one of the preceding claims, wherein the second circumferential portion (13) comprises a cavity (14) which is radially open towards the delivery rotor (5) and is not axially continuous, and the cavity (14) exhibits a circumferential extent, from the first circumferential portion (11) in the rotational direction of the delivery rotor (5), which at most corresponds to a maximum distance between two adjacent delivery means (6) as measured in the circumferential direction.

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