screw pump

Abstract

A screw pump having a main shaft housing (2) in which a drive main shaft (3) and at least one driven main shaft (4) engaged therewith are accommodated in main shaft boreholes, and having an outer housing (5) surrounding the main shaft housing (2), on which an axial inlet connection (6) and a radial outlet connection (9) are arranged, the main shaft housing (2) having an axial fluid outlet for fluid conveyed through the main shaft housing (2) via the drive main shaft and the driven main shaft, and having a drive motor (11) comprising a drive shaft (12) which extends through a borehole (23) in a housing wall (15) axially closing off the interior of the outer housing (5) and is coupled to the drive main shaft (3), wherein a portion of the fluid flowing out of the fluid outlet of the main shaft housing (2) flows along the drive shaft (12) through the unsealed borehole (23) into the drive motor (11), is cooled there and flows back into the outer housing (5).

Description

Technical Field

[0001] The invention relates to a screw pump comprising a spindle housing, in which a drive spindle and at least one driven spindle meshing with the drive spindle are accommodated in a spindle bore, and an outer housing surrounding the spindle housing, on which an axial inlet connection and a radial outlet connection are arranged. Background Art

[0002] This type of screw pump is used to pump fluids and has applications in a variety of fields. For example, it can pump fuel or other working fluids or supply fluids such as coolants or cleaning agents in automobiles. This type of screw pump can also be used in other land vehicles and aircraft, such as airplanes or drones, but the possible applications are not limited to these. This screw pump has a spindle housing, also known as an inner housing, in which at least two spindles—a driving spindle and a driven spindle—are housed in corresponding spindle bores, which intersect with each other. The driving spindle and the driven spindle each have a spindle profile, which meshes with each other. The driving spindle is connected to a drive motor and can be actively rotated, which also causes the meshing driven spindle to rotate. The spindle rotation continuously moves the delivery volume toward the longitudinal axis of the spindle, into which the fluid is delivered. The spindle housing is housed in an outer housing, which can be, for example, cylindrical and closed on one side by an axial wall and, on the other side, flange-mounted, for example, for the drive motor. However, the outer housing can also be composed of multiple parts and have a cylindrical base part that is closed on one side by a top cover and on the other side the drive motor is flange-mounted. The outer housing has an axial inlet connection, i.e., a corresponding connection piece for connecting to the delivery line, which defines the suction side. The outer housing also includes a radial outlet connection, i.e., a corresponding outlet connection piece for defining the pressure side. There, the pumped fluid escapes due to the corresponding pressure that can be generated by the pump. Such a pump is described, for example, in DE 10 2018 131 587 A1.

[0003] In known pumps, the feed occurs through an axial inlet connection, eccentrically arranged on the outer housing. The fluid then initially flows laterally to the axial inlet bore of the spindle housing, is conveyed through this bore, and leaves the spindle housing at a radial housing bore. From there, it flows through the narrow connecting space between the spindle housing and the outer housing to the radial outlet connection. In other words, the pressurized fluid leaves the spindle housing radially and is ultimately discharged directly through the outlet connection. Summary of the Invention

[0004] The present invention is based on the following problem: to propose an improved screw pump.

[0005] The solution of the present invention to achieve the above-mentioned object is to provide a screw pump as described above, wherein the main shaft housing has an axial fluid outlet for the fluid to be transported through the main shaft housing via the driving main shaft and the driven main shaft, and the screw pump has a drive motor, which includes a drive shaft, which extends through a borehole in the housing wall axially closing the interior of the outer housing and is coupled to the drive main shaft, wherein a part of the fluid flowing out of the fluid outlet of the main shaft housing flows along the drive shaft through the unsealed borehole into the drive motor, cools the drive motor and flows back into the outer housing.

[0006] The screw pump according to the present invention is characterized in that, on the one hand, the pumped pressurized fluid has an additional cooling function, and, on the other hand, the pump does not have any rotationally stressed sealing elements susceptible to wear. According to the invention, the spindle housing has an axial fluid outlet, meaning that fluid both enters the spindle housing axially and escapes axially. A drive motor is provided in the direction of escape, having a drive shaft that extends through a housing wall that axially closes the outer housing or pump housing and projects into the interior of the outer housing through a bore provided therein. There, the drive shaft is coupled to the drive spindle via a suitable coupling device to drive the drive spindle. While the housing wall axially closes the pump housing, it leaves a small annular gap, meaning the bore diameter is slightly larger than the drive shaft diameter. Through this annular gap, a small portion of the pressurized fluid delivered can flow axially from the pump housing along the drive shaft into the housing of the drive motor. The fluid is distributed accordingly in the housing of the drive motor according to the flow path and, in this manner, cools the motor in the area of ​​the surfaces or motor elements along or around which the fluid flows. The fluid circulates in the motor housing and flows back along the drive shaft into the outer housing. However, this return flow can also occur via one or more smaller through-holes in the housing wall. This fluid can be used to actively cool the motor, resulting in a wet rotor. This active cooling has a positive impact on efficiency and motor power.

[0007] As described above, the fluid flows axially into the motor housing, or can also flow back into the outer housing, at least along the drive shaft, through the borehole or the annular gap between the inner wall of the borehole and the drive shaft. This means that no sealing device, such as a shaft sealing ring, is accommodated in the borehole or the annular gap. Consequently, no rotationally loaded sealing elements, which are susceptible to wear over time, are provided in this area. In other words, aside from the corresponding bearing arrangement and any sealing of the drive shaft in the motor housing itself, the drive shaft is not guided in a radially sealed manner at the transition to the outer housing or within the outer housing. The other two rotating elements besides the drive shaft, namely the driving spindle and the driven spindle, are also not sealed by rotationally loaded sealing elements. In other words, no rotating element of the screw pump on or in the outer housing or spindle housing is sealed by a rotationally loaded sealing element. This advantageously prevents wear of the sealing elements. The only sealing elements are static sealing elements, which axially and / or radially seal, for example, the transition between the outer housing and the motor housing, the transition between two outer housing components, and similar transitions. However, these sealing elements are not subject to mechanical changes during operation and are therefore less susceptible to wear.

[0008] As described above, the drive shaft from the drive motor extends through a borehole in the housing wall that axially closes the outer housing. Different variations can be used with respect to the layout or design of the housing wall. According to a first alternative, the drive motor can be placed directly onto the outer housing, wherein the housing of the drive motor has end walls that form the housing walls. That is, the housing of the drive motor, in which the corresponding motor components (such as the rotor and stator as well as electronic components, etc.) are accommodated, is provided with an axial housing wall, in which corresponding boreholes are constructed, through which the drive shaft passes. The drive motor is placed directly onto the outer housing and screwed together with the outer housing, so that the housing wall on the drive motor side forms an axial outer housing closure. As a result, part of the cooling fluid flows directly into the drive motor through the housing wall on the drive motor side.

[0009] As an alternative, a plate-like intermediate member can be provided, which is placed onto the outer housing and forms a housing wall, wherein the drive motor is placed onto the intermediate member. In this variant, the intermediate member is placed between the outer housing and the drive motor or motor housing, ultimately forming a mounting interface. The plate-like intermediate member has a housing wall comprising a bore, through which the motor-side drive shaft passes. The motor housing can thus ultimately be embodied in such a way that it is open on the side facing the intermediate plate, or, for example, in the case where cooling of the electronics should only take place there, the motor housing is designed with a corresponding closed wall behind which the electronics are located, wherein a fluid flow is directed to the closed wall for cooling purposes, etc. The intermediate member has, for example, corresponding through-holes for guiding fixing screws by means of which the outer housing with the corresponding bore and the motor housing are guided in order to screw all three components to one another axially by means of the shared fixing elements.

[0010] As already described in the background, in pumps such as that described in DE 10 2018 131 587 A1, only one radial housing opening is provided in the spindle housing, from which the pumped pressurized fluid flows radially into the narrow connecting space between the spindle housing and the outer housing and from there to the radial outlet connection. In the region of this radial housing opening and the narrow connecting space of the spindle housing, i.e., on the pressure side, the pumped fluid has a correspondingly higher pump pressure, thereby exerting a higher pressure locally on the spindle housing or in the intermediate housing region where the narrow connecting space is provided. In the screw pump according to the present invention, there is no radial outlet from the spindle housing, but rather an axial outlet, so that part of the fluid used for cooling purposes can flow axially into the motor housing. The remaining fluid volume is directed to the radial outlet connection provided on the outer housing, for which purpose it is deflected. According to an advantageous further development, the axial fluid outlet for the fluid conveyed through the spindle housing via the drive and driven spindles advantageously communicates with a fluid chamber extending 360°, formed between the spindle housing and the outer housing, which in turn communicates with a radial outlet connection. In the screw pump according to the present invention, the radial fluid chamber is advantageously arranged between the spindle housing and the outer housing, extending 360° around the spindle housing, i.e., surrounding the spindle housing as an annular chamber. This annular fluid chamber is located on the pressure side, i.e., is a pressure chamber, because the pressurized fluid escaping from the spindle housing is fed into it. The fluid escapes axially from the spindle housing, i.e., a correspondingly large axial fluid outlet opening is provided in the spindle housing. As described above, no radial bores or similar structures are provided. This is because, as described above, the radial fluid chamber or pressure chamber completely surrounds the inner housing, i.e., circumferentially encircling it 360°. The corresponding pump pressure is particularly advantageously applied all around the inner housing, ultimately achieving or exerting nearly symmetrical pressure conditions on the spindle housing. This prevents localized pressure increases, such as those caused by asymmetrical pressure distribution known from the prior art. Furthermore, minor deformations of the spindle housing caused by the fluid pressure also building up in the spindle housing are prevented because, as previously described, the spindle housing is loaded radially outward by the fluid pressure in the fluid chamber and is therefore stabilized. In other words, the present invention provides a fluid jacket that generates a corresponding radial pressure that stabilizes the inner housing. This is particularly advantageous when the spindle housing is made of a relatively soft material, such as plastic, as is the case with smaller screw pumps, which nonetheless generate correspondingly high pump pressures.

[0011] The fluid chamber provided according to the present invention, as previously described, extends 360° around the spindle housing. Furthermore, the fluid chamber should surround the spindle housing for at least a portion of its axial length. In this case, the fluid chamber should extend for at least half the length of the spindle bore or spindle housing, and optionally longer, for example, for two-thirds of the length of the spindle bore or spindle housing. Alternatively, the fluid chamber can extend over the entire length of the spindle bore or spindle housing.

[0012] The spindle housing should be supported accordingly in the outer housing, just as the fluid chamber must of course be sealed axially accordingly. To this end, different schemes can be adopted. According to a first alternative, the fluid chamber can be axially limited by two radial flanges, one of which has a plurality of axial through-holes, through which the fluid chamber is connected to the fluid outlet of the spindle housing. The spindle housing is accommodated in the outer housing and supported radially by these radial flanges. The radial flange arranged on the pressure side has corresponding through-holes, which enable the fluid flowing out axially from the spindle housing to flow back axially roughly into the fluid chamber after its deflection. Of course, it is necessary to seal on this side. The other radial flange arranged on the suction side is used for sealing, and for this purpose, one or more suitable seals are provided in this area for sealing the spindle housing toward the outer housing so that the fluid chamber is also sealed at the end of the suction side.

[0013] As an alternative to constructing two radial flanges, the fluid chamber can also be axially delimited by a radial flange and a cover member, the radial flange having a plurality of axial through-holes, via which the fluid chamber is connected to the fluid outlet of the spindle housing. In this case, only the radial flange disposed on the pressure side is used, which, as described in the previous embodiment, has axial through-holes to allow the supplied pressurized fluid to flow back into the fluid chamber. The other side of the fluid chamber is closed or delimited by a cover member placed on the cylindrical base part of the outer housing, on which the inlet connection is provided. Thus, in the first variant, the chamber is delimited by the suction-side radial flange, while in the second variant, the axial chamber delimitation is achieved by the cover member.

[0014] In order to axially deflect the fluid flowing out of the spindle housing into the fluid chamber, according to a first variant, the end wall of the drive motor housing can have one or more deflection cavities that deflect the fluid from the fluid outlet into the fluid chamber. In this variant, the drive housing is provided with a housing wall that axially closes the outer housing, wherein the housing wall is provided with one or more deflection cavities that enable radial and axial deflection into the fluid chamber radially surrounding the spindle housing.

[0015] When an intermediate component is used between the outer housing and the motor housing, the intermediate component can have one or more deflection chambers for deflecting the fluid into the fluid chamber. As explained, the intermediate component has a housing wall that axially closes the outer housing, so in this case the intermediate component must be equipped with one or more deflection chambers.

[0016] The deflection chamber is preferably an annular groove or cylindrical depression with a rounded bottom. In other words, the housing wall is convex in an approximately dome-shaped manner, forming a corresponding groove or depression. The fluid can initially flow axially into this groove or depression, which then extends radially outward, thereby guiding the fluid radially outward. Because this depression is connected to the fluid chamber, either directly or via corresponding through-holes in the radial flange on the spindle housing side, the fluid can then flow axially back into the fluid chamber and be distributed there before flowing to the fluid outlet. Thus, this concave or dome-shaped depression deflects the fluid on all sides and allows the fluid to flow symmetrically into the fluid chamber. Of course, if axially and radially extending webs are provided, for example for stabilization purposes, the groove or depression can also be divided into separate groove or depression sections by such webs. In addition to providing targeted flow guidance, the rounded design of the groove or depression bottom also ensures that flow noise is not generated in this case, as there are no corners or edges in the groove or depression area that would be disadvantageous from a fluidic perspective.

[0017] As described above, the fluid or pressure sheath implemented according to the invention by the fluid chamber can specifically generate a radially stable pressure applied to the spindle housing in all directions in order to avoid the expansion of tolerances on the spindle housing or any minor operational-related geometric changes. This solution can be used in particular if the spindle housing is made of plastic, as provided in accordance with the invention. In addition, as a supplement or alternative, the outer housing and the intermediate components can also be made of plastic, or (if a top cover component is provided) the top cover component can be made of plastic as an axial outer housing closure. In other words, all housing-related components can be made of plastic, but in addition, the spindle itself can also be made of plastic in principle. However, preferably, at least these spindles are made of metal.

[0018] A screw pump can be a dual-spindle pump with only one drive spindle and one driven spindle positioned laterally relative to the drive spindle. Alternatively, a screw pump can be a triple-spindle pump with a central drive spindle and two driven spindles positioned 180° apart. Thus, different types of pumps can be implemented using the present invention.

[0019] Furthermore, the inlet connection can be arranged in such a way that it is aligned with the center axis of the spindle group, which comprises the drive spindle and one or two driven spindles. This means that the inlet connection is arranged approximately in the axial extension of the center axis of the spindle group. In the case of a twin-spindle screw pump, the center axis is ultimately located centrally between the drive spindle and the driven spindle. In the case of a triple-spindle pump, the center axis lies in the longitudinal axis of the central drive spindle. This technical solution is particularly advantageous in that the fluid flowing into the outer casing and being axially drawn in does not first need to be deflected into the spindle housing, which could be associated with flow noise. Rather, it can flow directly axially into the spindle housing.

[0020] In addition to the screw pump itself, the present invention also relates to the use of a screw pump of the aforementioned type in a vehicle for conveying a working fluid. The working fluid can be of any nature. For example, it can be a cleaning fluid, such as windshield washer fluid, which is conveyed by a pump. As an alternative, the preferred use according to the present invention is to use the screw pump as a coolant pump for conveying a coolant. The coolant can be any fluid coolant. The use relates in particular to the use for conveying a coolant for cooling an energy accumulator. Such energy accumulators are increasingly used in motor-driven vehicles and are provided in the form of traction or power batteries of corresponding dimensions. The energy accumulator needs to be appropriately cooled with the aid of a coolant, which can be simply conveyed in the required amount by the screw pump according to the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Other advantages and details of the present invention are described in the following embodiments and the accompanying drawings, wherein:

[0022] Figure 1 A schematic cross-sectional view of a screw pump according to a first embodiment of the present invention is shown.

[0023] Figure 2 is a principle sectional view of a screw pump according to a second embodiment of the present invention, and

[0024] Figure 3 2 is a schematic cross-sectional view of a screw pump according to a third embodiment of the present invention. DETAILED DESCRIPTION

[0025] Figure 1 A screw pump 1 according to a first embodiment of the invention is shown. The screw pump comprises a spindle housing 2 in which, in the example shown, three spindles (i.e. a driving spindle 3 and two driven spindles 4, positioned next to one another with a lateral offset of 180°) are accommodated in respective spindle bores that intersect one another. Figure 1 As shown, all spindles 3 , 4 have corresponding spindle profiles that engage with each other and mesh with each other.

[0026] The spindle housing 2 is accommodated in a cylindrical outer housing 5, on which a central inlet connection 6, i.e., a corresponding connection piece, is located, aligned with the longitudinal axis of the drive spindle 3. The spindle assembly consisting of the drive spindle 3 and the driven spindle 4 is axially supported by a supporting element, here a key 8, against the outer housing 5 or its radial flange 7. The key 8 is held in the outer housing 5, for example, by clamping or snapping into a radial recess in the outer housing 5.

[0027] Furthermore, a radial outlet connection 9 , here also a connecting piece, is provided on the outer housing 5 , which is made of plastic, for example, and through which the pressurized fluid drawn in via the inlet connection 6 can escape radially again.

[0028] like Figure 1 As shown clearly, the spindle housing 2 together with its components is accommodated inside the cylindrical outer shell 5. A 360° surrounding fluid chamber 10 is provided between the outer wall of the spindle housing 2 and the inner wall of the outer shell 5. Figure 1 As shown, the fluid chamber extends over half the length of the spindle housing 2 or the spindle bore. Pressurized fluid escaping at the axial fluid outlet of the spindle housing enters the fluid chamber 10, i.e., the axial fluid outlet at the left end of the spindle housing 2 communicates with the fluid chamber 10. This fluid chamber, in turn, communicates with the outlet connection 9.

[0029] Furthermore, a drive motor 11, shown here only in principle, is provided, which is placed directly on the outer housing 5 and secured there by suitable fixing screws. By means of a drive shaft 12 (which is connected to a rotor 13 of the drive motor 11, which is arranged in a stator (not shown in detail here) and is designed as an electric motor), the drive motor 11 is coupled to the drive spindle 3 via a coupling element 22, so that the drive spindle can be actively rotated by the drive motor 11, so that the entire spindle assembly rotates and axially conveys the fluid drawn in through the inlet connection 6.

[0030] As described above, the fluid escapes from the axial fluid outlet of the spindle housing. In this embodiment, this fluid outlet is simply axially open at the suction and pressure side ends. To ensure that the escaping fluid can enter the fluid chamber 10, which is axially offset with respect to the delivery direction, a deflection chamber 14 is provided in the illustrated example. In this example, the deflection chamber is directly formed in the housing wall 15 of the drive motor 11, which faces the spindle housing 2. The housing wall 15 forms an axial closure for the outer housing 5, i.e., the outer housing is closed on this side. The deflection chamber 14 is designed, for example, as a circumferential annular groove or as a cylindrical, dome-shaped depression with a curved or rounded bottom side. This deflects the fluid flowing approximately centrally radially outward toward the sides and conveys it back, allowing it to flow into the fluid chamber 10 through corresponding through-holes 16 formed in a radial flange 17 of the spindle housing 2.

[0031] The fluid chamber 10 is axially limited at the suction side end by a radial flange 18 of the spindle housing 2. This radial flange is supported on the housing shoulder 19 of the outer housing 5 on the one hand. On the other hand, it extends to the inner wall of the outer housing 5 and is radially sealed against the outer housing by a sealing element 20, so that the fluid chamber 10 is closed and sealed at this end. At the opposite, pressure side end, there is also a radial flange 17, in which the through hole 16 mentioned is built, so that the fluid chamber 10 is open towards the pressure side and the pressurized fluid can flow into the fluid chamber through the deflection chamber 14. On this side, the outer housing 5 is sealed against the motor housing by a suitable sealing element 21, which is built on an annular flange of the motor housing that engages approximately axially into the outer housing 5 and is sealed radially.

[0032] During operation, the spindle 3 is rotated by the drive motor 11. The fluid taken in through the inlet connection 6 is axially conveyed in that the spindle contours of the spindles 3, 4 engage into one another in order to create an axially moving conveying volume, which allows the fluid to be conveyed along the spindle group.

[0033] The fluid axially escapes at the pressure side end of the spindle housing 2, which is advantageous in terms of as low noise operation as possible, since no significant flow noise occurs in this regard. The fluid then directly enters the deflection chamber 14, which is, for example, an annular groove or a concave recess, as described above, through which the fluid is deflected radially outwards and axially back, i.e. in the opposite direction to the conveying direction of the spindle group. The fluid enters the fluid chamber 10 through the through hole 16 and via the fluid chamber into the outlet connection 9, where it is discharged.

[0034] There is a pump pressure in the fluid chamber 10, that is to say, an outlet pressure that is exerted in all directions in the fluid chamber 10, which can be generated by the screw pump 1. This pressure acts radially in all directions on the spindle housing as long as the spindle housing 2 is surrounded by the fluid chamber 10, which can also be referred to as a pressure chamber. As described above, the fluid chamber 10 extends over at least half the length of the spindle housing 2, preferably even over a longer range, in order to achieve the best stabilization of the spindle housing 2 despite possible pressure-related geometric changes or tolerance shifts. The above is particularly applicable when the spindle housing is made of plastic, i.e. a softer material compared to metal.

[0035] As described above, the pumped fluid axially escapes from the spindle housing 2 and enters the deflection chamber 14, i.e. flows against the housing wall 15. While a large part is deflected and discharged, a small part of the pressurized fluid enters the drive motor 11 for cooling purposes, as described above, for example. Figure 1To achieve this, a fluid flow can be achieved between the drive spindle 12 and the inner wall of a borehole 23 formed in the housing wall 15. For this purpose, the inner diameter of the borehole 23 is slightly larger than the outer diameter of the drive spindle 12, thereby generating an annular gap 24 through which the fluid can flow. Figure 1 The fluid flowing axially from the right can flow along the drive shaft 12 through the housing wall 15 into the interior of the motor housing or drive motor 11. The fluid flows there, provided that appropriate fluid paths are provided, or so that it passes over the corresponding surfaces or components to be cooled and also flows back through the annular gap 24 into the region of the deflection chamber 14, from which it ultimately enters the fluid chamber 10 and is discharged. In other words, the drive motor 11 can be actively cooled by the supplied cooling fluid, which escapes from the spindle housing 2 in an axial flow direction and flows precisely in this direction in an axial extension through the annular gap 24 and into the motor housing or drive motor 11. This active cooling is highly advantageous for motor operation and the achievable motor power and efficiency.

[0036] The drive motor 11 is shown here only in a non-realistic manner. It has a motor housing, for example made of metal or plastic, which encloses the drive motor itself and, in part, forms the housing wall 15. The housing wall is designed as a quasi-dome-shaped depression to form the deflection chamber 14. Support elements 25 can be formed at the bottom of this depression. These support elements extend axially to the spindle housing 2 and are axially supported on these support elements 25. Support is provided on the other side by a key 8. The drive spindle is also supported on the key 8, but also on the drive shaft 12.

[0037] Depending on the cooling requirements, appropriate cooling sections for guiding the coolant can be constructed within the drive motor 11. The cooling fluid can flow along a plate or similar object, behind which the corresponding electronic components are located. Alternatively, it can flow through the rotor and stator arrangement, as shown in this example. In other words, the guidance of the fluid through the drive motor 11 is designed based on the needs and cooling requirements.

[0038] exist Figure 1In the middle, corresponding flow arrows are illustrated, showing the fluid flow. The fluid enters from the right side through the inlet connection 6 of the suction side and into the main shaft housing 2, which is axially open on this side, until it enters the main shaft group, which is rotated by the drive motor 11. The fluid is pushed axially through the main shaft group as shown by the arrows and escapes at the outlet connection of the main shaft housing 2, which is also axially open on the pressure side. The majority of the fluid is deflected radially outward as shown by the deflection arrows and enters the fluid chamber 10, in which the fluid exerts a corresponding stabilizing pressure on the main shaft housing 2. From there, the fluid then enters the outlet connection 9 and is discharged. Another part, as shown by the flow arrows, passes through the annular gap 24 into the drive motor 11, is circulated through the drive motor and also flows back again into the annular gap 24, where it finally enters the fluid chamber 10 and is discharged.

[0039] Figure 2 is shown. The structure is ultimately the same as Figure 1 shown, and the basic function is also the same. The only difference here is that a plate-like intermediate member 26 is provided between the drive motor 11 and the outer housing 5, all three components, i.e. the outer housing 5, the intermediate member 26 and the drive motor 5 or motor housing, are axially connected to one another by a common fixing. In this embodiment, the intermediate member 26 forms the housing wall 15, which axially closes the outer housing 5 on this side and on which the deflection chamber 14 is constructed. The intermediate member 26 or its housing wall 15 is also provided here with a corresponding bore 23, so that an annular channel 24 is also formed here between the drive shaft 12 and the bore inner wall, through which the fluid flowing axially from the main shaft housing 2 also enters the interior of the motor housing or drive motor 11 here and is circulated here for cooling purposes and can also flow back again. The fluid finally enters the fluid chamber 10 together with the fluid that is normally fed back via the deflection chamber 14 in other cases, and then flows from the fluid chamber through the outlet connection 9.

[0040] That is, unlike the structure shown in Figure 1 , the intermediate member 26 is connected here roughly sandwich-like between the outer housing 5 and the drive motor 11, the outer housing closure being achieved by the intermediate member 26. The drive motor 11 can therefore be designed as open on the side facing the intermediate member 26, if necessary, since, as mentioned above, the outer housing closure is achieved by the intermediate member 26. The annular gap 24 is therefore formed here only in the intermediate member 26, not on or in the motor housing.

[0041] The configuration of the deflection chamber 14 of the intermediate member 26 can be the same as according to Figure 1The deflection chamber 14 of the illustrated embodiment is identical. Here, the deflection chamber 14 is also preferably designed as a cylindrical depression, in which two support elements 25 are formed, for example. Like the spindle housing 2, the intermediate component 26 can also be a plastic component, and this is also true for the outer housing 5.

[0042] at last, Figure 3 The schematic diagram shows a third exemplary embodiment of a screw pump 1 according to the invention, which has a spindle housing 2 and a drive spindle 3 and two output spindles 4 accommodated therein. Here, the spindle housing 2 is also accommodated in an outer housing 5, which, however, is designed in two parts. This outer housing consists of a quasi-hollow-cylindrical base part 27, which is axially closed on the suction side by a cover component 28, on which the inlet connection 6 and the outlet connection 9 are provided. The cover component 28 is placed on the base component 27 and radially spans it, with corresponding seals (not shown in detail) being provided in this area.

[0043] Furthermore, in this embodiment of the invention, an intermediate component 26 is provided, which forms the housing wall 15, in which the deflection chamber 14 is in turn formed. The drive motor 11, also shown here only in a non-graphic manner, passes through a bore 23 in the housing wall 15 with its drive shaft 12, thereby also forming an annular gap 24 here, which allows fluid to flow axially from the spindle housing 2 into the drive motor 11 and back for cooling purposes. A corresponding fluid chamber 10 is also provided here, forming a pressure jacket around the spindle housing 2 and communicating with the fluid outlet of the spindle housing 2 on the one hand and with the outlet connection 9 on the other. The basic functionality of the screw pump 1, shown here only in principle, corresponds to that of the previous embodiment, differing only in that the outer housing 5 is designed as a two-part outer housing.

Claims

1. A screw pump comprising a spindle housing (2), in which a drive spindle (3) and at least one driven spindle (4) meshing with the drive spindle are accommodated in a spindle bore, and the screw pump comprises an outer housing (5) surrounding the spindle housing (2), on which an axial inlet connection (6) and a radial outlet connection (9) are arranged, wherein the spindle housing (2) has an axial fluid outlet for a fluid conveyed through the spindle housing (2) via the drive spindle (3) and the driven spindle (4), and the screw pump A drive motor (11) is provided, comprising a drive shaft (12), which extends through a borehole (23) in a housing wall (15) axially closing the interior of the outer housing (5) and is coupled to the drive spindle (3), wherein a portion of the fluid flowing out of the fluid outlet of the spindle housing (2) flows along the drive shaft (12) through the unsealed borehole (23) into the drive motor (11), cools the drive motor and flows back into the outer housing (5) along the drive shaft through the borehole or through one or more holes in the housing wall.

2. The screw pump according to claim 1, characterized in that The drive motor (11) is placed directly on the outer housing (5), wherein the housing of the drive motor (11) has an end wall forming the housing wall (15).

3. The screw pump according to claim 1, characterized in that A plate-shaped intermediate component (26) is provided, which is placed on the outer housing (5) and forms the housing wall (15), wherein the drive motor (11) is placed on the intermediate component (26).

4. The screw pump according to claim 1, characterized in that An axial fluid outlet for the fluid conveyed through the spindle housing (2) via the drive spindle (3) and the driven spindle (4) communicates with a fluid chamber (10) extending 360°, constructed between the spindle housing (2) and the outer housing (5), which in turn communicates with the radial outlet connection (9).

5. The screw pump according to claim 1, characterized in that A plate-shaped intermediate component (26) is provided, which is placed on the outer housing (5) and forms the housing wall (15), wherein the drive motor (11) is placed on the intermediate component (26), and the axial fluid outlet for the fluid conveyed through the spindle housing (2) via the drive spindle (3) and the driven spindle (4) is connected to a fluid chamber (10) extending 360° constructed between the spindle housing (2) and the outer housing (5), and the fluid chamber is in turn connected to the radial outlet connection (9).

6. The screw pump according to claim 4, characterized in that The fluid chamber (10) extends over at least half the length of the spindle bore.

7. The screw pump according to claim 4 or 6, characterized in that The fluid chamber (10) is axially limited by two radial flanges (17, 18), one of which has a plurality of axial through holes (16), through which the fluid chamber (10) is connected to the fluid outlet of the spindle housing (2), or the fluid chamber (10) is axially limited by a radial flange (17) and a top cover member (28), the radial flange having a plurality of axial through holes (16), through which the fluid chamber (10) is connected to the fluid outlet of the spindle housing (2).

8. The screw pump according to claim 4, characterized in that The end wall of the housing of the drive motor (11) has one or more deflection cavities (14) for deflecting the fluid from the fluid outlet of the spindle housing (2) to the fluid chamber (10).

9. The screw pump according to claim 5, characterized in that The intermediate member (26) has one or more deflection chambers (14) for deflecting fluid from the fluid outlet of the spindle housing (2) to the fluid chamber (10).

10. The screw pump according to claim 8 or 9, characterized in that The deflection cavity (14) is an annular groove or a cylindrical depression, which is rounded in the area of ​​the groove or depression bottom.

11. The screw pump according to any one of claims 1 to 6, characterized in that The spindle housing (2) and / or the outer housing (5) are made of plastic.

12. The screw pump according to claim 3, characterized in that The intermediate member (26) is made of plastic.

13. The screw pump according to any one of claims 1 to 6, characterized in that A central driving spindle (3) and two driven spindles (4) arranged on both sides of the driving spindle are provided.

14. The screw pump according to claim 13, characterized in that The inlet connector (6) is arranged in a manner aligned with the central axis of a spindle group comprising the driving spindle (3) and one or two driven spindles (4).

15. Use of a screw pump (1) according to any one of claims 1 to 14 for pumping a working fluid in a motor vehicle.

16. The use according to claim 15, characterized in that The screw pump (1) is used as a coolant pump.

17. The use according to claim 16, characterized in that The coolant pump is used to transport the coolant for cooling the energy storage device.

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